Synthegen Cherry Lime by Morphogen Nutrition

Hepatic encephalopathy. Oral and intravenous BCAAs improve symptoms and nutritional status in patients with hepatic encephalopathy, especially in those not tolerating protein supplementation. Details: Taking BCAAs 240 mg/kg (up to 25 grams) daily in 3 divided doses for up to 3 months can improve symptoms, liver function tests, and nitrogen balance in patients with chronic hepatic encephalopathy (68,69,82,690,92643,97531). Oral BCAAs are recommended for malnourished patients with chronic hepatic encephalopathy who cannot tolerate protein supplementation (69,4274). When the enteral route is unavailable and when patients cannot tolerate general purpose amino acid solutions, intravenous solutions with BCAAs can be used for nutritional support; however, most patients can tolerate standard amino acid mixtures (4274). Some clinical research also suggests that taking BCAAs orally improves psychomotor function, attention, intelligence, and driving ability in patients with latent hepatic encephalopathy (684,685,37131,97531). However, not all studies show a positive effect of BCAAs on psychometric outcomes (37135). There is also some preliminary evidence that intravenous BCAAs might be helpful for reversing coma in acute hepatic encephalopathy, although findings are conflicting (66,81,686,687,688,689,4274,37134). BCAAs do not appear to reduce the risk of mortality or improve quality of life in patients with hepatic encephalopathy (92643,97531).
Tardive dyskinesia. Oral BCAAs might reduce symptoms of tardive dyskinesia precipitated by antipsychotic drugs. Details: Taking BCAAs orally seems to reduce symptoms of tardive dyskinesia (72,10146,13307). Clinical research in adult and pediatric patients who are taking antipsychotic drugs shows that taking a drink containing BCAAs 222 mg/kg three times daily for 3 weeks reduces tardive dyskinesia movements by 30% to 60% when compared with placebo (10146,13307).

Liver cancer. Oral BCAAs do not seem to improve outcomes or reduce the risk for recurrence in patients with liver cancer. Details: A meta-analysis of the available clinical research, as well as individual clinical studies, in patients with hepatocellular carcinoma show that consuming up to 50 grams of BCAAs twice daily for up to 4 years does not improve survival, reduce tumor recurrence, or reduce the risk of complications such as ascites following liver resection when compared with a control group receiving no intervention (37143,92646,97532,105578). However, one small clinical study suggests that BCAAs may be beneficial in patients recently diagnosed with hepatocellular carcinoma that does not require surgery. Taking two packets of a specific supplement (Aminoleban EN) daily containing a total of L-leucine 4 grams, L-isoleucine 3.8 grams, and L-valine 3.2 grams, starting two weeks before receiving transcatheter arterial chemoembolization and radiofrequency ablation and continuing for up to 5 years, reduces recurrence of liver cancer and increases event-free survival when compared with placebo (97533). However, the validity of these findings is limited by the high withdrawal rate in this study.

LIKELY INEFFECTIVE

Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Overall, oral BCAAs are not beneficial and might even lead to worsened outcomes in patients with ALS. Details: Although early studies have indicated that taking BCAAs might be beneficial in ALS, more recent studies show no benefit and a possible increased loss of pulmonary function and higher rate of mortality among patients using BCAAs (678,679,680,681,37154).

Alzheimer disease. It is unclear if dietary BCAAs prevent Alzheimer disease. Details: Observational research has found that higher blood levels of BCAAs are associated with an 11% to 13% lower risk of Alzheimer disease; however, when research was adjusted for mortality, body mass index, and concomitant cholesterol-lowering medications, the association was no longer significant (100469).
Athletic performance. Small clinical trials suggest that although oral BCAAs may not enhance athletic performance, they may modestly reduce perceived exertion and fatigue with some forms of exercise. Details: In most studies, taking BCAAs orally does not enhance athletic performance (692,1135,37080,37094,37106,37123,37141,37142,37151,92641). For instance, BCAAs do not appear to improve strength or work power or to reduce completion times for long-distance running or cycling trials (692,37106,37112,37141,37142,92641). However, most research shows that BCAAs are beneficial for reducing exercise-induced fatigue and perceived exertion after prolonged or intense exercise, exercise in the heat, or exercise following glycogen depletion (692,37112,37124,37144,92642,92644,92645,92648,97529,97530)(97535,105582). In many cases, this improvement is observed when BCAAs are taken in combination with arginine, citrulline, or green tea powder (37124,92642,92645,92648,97529,100462). However, some conflicting evidence exists (1135,37080,37094). Overall, the validity of these findings is limited because most studies differ widely in the amount and type of product consumed. For example, studied doses included BCAAs 0.17-0.3 mg/kg daily; or valine 0.5-1.7 grams, leucine 1-3.5 grams, and isoleucine 0.48-2.1 grams given before and/or after exercise (37108,37123,92642,92644,92645). Other limitations include variability in the studied endpoints and control comparisons used.
Bipolar disorder. It is unclear if oral BCAAs are beneficial in patients with bipolar disorder. Details: One small clinical study shows that consuming a tyrosine-free amino acid drink containing 60 grams of the BCAAs leucine, isoleucine, and valine in a ratio of 3:3:4, reduces acute manic symptoms within 6 hours when compared with placebo. When taken daily for 7 days, it seems to continue to improve symptoms over a 2-week period (10117).
Cachexia. Small clinical studies suggest that oral BCAAs are beneficial in patients with cachexia from various causes. Details: Preliminary clinical research in elderly malnourished patients receiving hemodialysis shows that taking a combination of BCAAs 4 grams three times daily improves appetite and caloric intake and increases plasma albumin levels and anthropometric measurements when compared with placebo (10147). Also, small clinical studies in adults with cachexia due to cancer or cirrhosis show that taking oral BCAAs 2.4 grams twice daily for 1 year or 4.8 grams 3 times daily for 1 week might be helpful when compared to baseline (71,37090). This finding is limited by the lack of a comparator group. A small clinical study in adults with congestive heart failure who have lost at least 7.5% of dry weight over the past 6 months or have a body mass index below 20 kg/m² shows that taking BCAAs 10 grams every evening at bedtime for 8 weeks improves physical and emotional quality of life scores, appetite, and fatigue when compared with placebo. Patients taking melatonin 20 mg nightly in addition to BCAA supplementation observed greater improvements in appetite and fatigue when compared with placebo (108478). However, a statistical comparison of outcomes between the groups taking BCAA alone or BCAA with melatonin was not provided.
Cancer. It is unclear if dietary BCAA consumption improves cancer-related mortality. Details: Observational research in adults has found that consuming BCAAs 19 grams or more daily as part of the diet is not associated with a reduced risk of cancer-related mortality when compared with a lower dietary BCAA intake of less than 7.8 grams daily (108467). The validity of this finding is limited due to unclear reporting; additionally, dietary intake was recorded from a single survey.
Cardiovascular disease (CVD). It is unclear if dietary BCAA consumption reduces the risk of CVD-related mortality. Details: Observational research in adults has found that CVD-related mortality is not associated with dietary BCAA intake or with individual leucine, isoleucine, or valine intake (108467). The validity of this meta-analysis is limited due to unclear reporting; additionally dietary intake was recorded from a single survey.
Chronic obstructive pulmonary disease (COPD). It is unclear if oral BCAAs can improve physical performance in adults with COPD. Details: A clinical study in adults with stable, stage 2 or 3 COPD undergoing a pulmonary rehabilitation program shows that taking a BCAA powder 4.3 grams, diluted in water and consumed once daily for 4 weeks, may improve recovery after exercise, but does not impact maximal exercise capacity, functional and muscular performance, or quality of life when compared with placebo (108464). The validity of these findings is limited due to the short duration of treatment.
Cirrhosis. Most small studies suggest that BCAAs may modestly improve certain measures in some patients with liver cirrhosis. Details: One small clinical study shows that although taking BCAAs 14.4 grams daily for 12 months does not improve survival or liver function in patients with advanced liver cirrhosis, the number of hospitalizations and prevalence of cachexia are reduced and quality of life is improved when compared with control or whey protein (37090). A clinical study in patients with sarcopenia and liver cirrhosis shows that taking BCAAs 7.2 grams for 6 months decreases bilirubin levels and improves Child-Turcotte-Pugh and model for end-stage liver disease (MELD) scores when compared with baseline (108468). Although the study enrolled a control group (whey protein), the investigators did not provide a statistical comparison of outcomes between groups. In addition, a small study in Japanese patients with cirrhosis shows that taking BCAAs 12.45 grams daily for at least 12 months improves liver function and reduces liver complications by 50% to 60% over 3-5 years when compared with control (37120). Also, taking a specific product (Livact, Samil Pharmaceutical) providing the same dose for 11-22 months improves liver function by a small to moderate amount over a 24-month period when compared with not taking BCAAs. There was also a moderate reduction in the rate of developing or worsening major complications such as ascites or hepatic encephalopathy (103351). However, some research providing BCAAs as part of a late evening snack has found no benefit. In one small study, consuming BCAAs as part of a late evening snack in an undefined dose for 3 months does not seem to improve quality of life when compared with a late evening snack without BCAAs (37101). Also, a very small clinical study in patients with abnormal glucose metabolism related to cirrhosis shows that consuming BCAAs in an undefined dose as part of a late evening snack for 1 week does not improve glycemic control when compared with baseline. Instead, glucose levels increased in some patients (103348). It is possible that the doses provided in these latter studies were lower than those used in the studies showing benefit. Additionally, these very small studies may not have been adequately powered to detect a difference between groups.
Colorectal cancer. It is unclear if dietary BCAAs are beneficial or harmful in patients with colorectal cancer. Details: An observational study in Italy has found that increased dietary intake of BCAAs is associated with a lower risk of developing sigmoid colon cancer, but not overall colorectal cancer risk, when compared with lower intake (105584). However, there's some concern that increased dietary BCAAs may have negative effects in patients who have been diagnosed with colorectal cancer. Observational research in patients living in the US has found that higher dietary intake of BCAAs is associated with a slightly higher risk of all-cause mortality when compared with lower intake (105581).
Dementia. It is unclear if dietary BCAAs help to prevent dementia. Details: Observational research has found that higher blood levels of BCAAs are associated with a 13% to 17% lower risk of dementia. The lowered risk was maintained when research was adjusted for mortality, body mass index, and concomitant cholesterol-lowering medications (100469).
Diabetes. It is unclear if dietary BCAAs reduce the risk for developing diabetes. Details: Some population research in Japanese females has found a decreased risk of diabetes associated with higher intake of BCAAs (97543). However, other observational research in people from the US has found that increased dietary intake of BCAAs is associated with an increased risk of diabetes (97536). Reasons for the conflicting finding are not entirely clear. Some evidence suggests that the dietary pattern of BCAA intake, rather than the total intake, may influence the risk of diabetes. Also, there is some speculation that differences in gut microbiota may attribute to the observed differences in diabetes risk associated with BCAA intake (100465). Prospective clinical research is needed to determine whether this association is causal or correlative.
Exercise-induced muscle damage. Small studies suggest that BCAAs might reduce some, but not all, markers of muscle damage caused by exercise. Details: A meta-analysis of small clinical studies shows that supplementation with BCAAs reduces creatine kinase (CK) levels 24 hours post-exercise, but not 48 hours post-exercise. Additionally, this analysis shows that lactate dehydrogenase (LDH) levels are not affected by BCAA supplementation (97534). The validity of this analysis was limited because baseline dietary protein consumption was not taken into consideration as a potential confounder. A separate meta-analysis of clinical research in trained male athletes performing various resistance exercises shows that taking BCAAs 0.2-1.76 grams/kg for 1-28 days improves CK levels immediately following exercise, and at 24 and 48 hours post-exercise, but does not reduce LDH levels at any timepoint, when compared with placebo or control (108469). Most doses of BCAAs studied consisted of a 2:1:1 ratio of leucine, isoleucine, and valine, respectively. The validity of these findings is limited due to the short duration of treatment and various doses studied. Small individual clinical trials show that taking BCAAs does not affect urinary myoglobin after a marathon nor plasma myoglobin or CK levels after isotonic muscular exercise (37123,92641,100471). The benefits of BCAAs might depend on baseline protein consumption. A small clinical study in resistance trained males shows that adding BCAAs 0.22 grams/kg (MusclePharm BCAA) daily for 8 days to a high daily protein consumption of 1.2 grams/kg does not attenuate muscle damage or improve muscle recovery when compared with placebo (100471). Conversely, a meta-analysis of clinical research in adults completing various exercises shows that taking BCAAs consisting of any combination of valine, leucine, and isoleucine ratios modestly reduces CK, LDH, and myoglobin 24 and 48 hours post-exercise, but does not improve muscle recovery or muscle force after exercise, when compared with placebo (108471). The validity of these findings is limited due to unclear reporting.
Exercise-induced muscle soreness. Limited evidence suggests that oral BCAAs may modestly attenuate exercise-induced muscle soreness. Details: One meta-analysis shows that taking BCAAs does not reduce delayed-onset muscle soreness after exercise when assessed at the individual time points of 24, 48, or 72 hours (97534). However, when results of all time points are pooled together in two separate meta-analyses, supplementation modestly reduces soreness after exercise (97534,103353). Most, but not all, individual trials also show that taking BCAAs in various doses, such as 0.087 grams/kg or 5-10 grams before and/or after exercise, modestly reduces muscle soreness after exercise (37108,37123,37124,92648,97530,97535,100467,100471,103346,108471). The validity of these individual trials is limited by their small sample sizes, variable dosing regimens, and enrolled populations, which were mainly limited to young untrained adult males (97534,103353). A separate meta-analysis of clinical research in trained male athletes performing various resistance exercises shows that taking BCAAs 0.2-1.76 grams/kg for 1-28 days may improve muscle soreness during the first 24 hours after exercise, but not at 24 or 48 hours post-exercise, when compared with placebo or control (108469). The validity of these findings is limited due to the short duration of treatment and various doses studied. Also, it is not clear whether taking BCAAs before or after a workout may be more beneficial. Some research found a nonsignificant trend toward reduced muscle soreness when consuming a specific product (Aminofeel, Seikatsu Bunkasya Co. Ltd.) containing BCAAs 3.2 grams three times daily starting 3 days before working out and continuing 3 days after, when compared to control (100467). More research is needed to determine the best dosing regimen and which populations, if any, may benefit.
Heart failure. It is unclear if oral BCAAs are beneficial in patients with heart failure. Details: A small clinical study in patients with heart failure and hypoalbuminemia shows that taking a specific packet of BCAA granules (LIVACT, Ajinomoto Co) containing L-valine 1144 mg, L-leucine 1904 mg, and L-isoleucine 952 mg, three times daily for at least 7 days and stopping after discharge from the hospital, does not affect serum albumin or cardiothoracic ratio (CTR) when compared with placebo (100470). It is possible that this study was underpowered to detect differences between groups. Another small clinical study in adults with chronic heart failure participating in a cardiac rehabilitation program shows that taking a specific oral supplement (Meiji Mei Balance Rehasupport Mini; Meiji Group) containing BCAAs 2.5 grams and various vitamins, minerals, and whey protein, twice daily for 12 weeks increases fat mass, but has no effect on peak oxygen uptake, 6-minute walking distance, or strength parameters, when compared with no supplementation (108470). It is unclear if these effects are due to BCAAs, the other ingredients, or the combination.
Hepatitis. It is unclear if oral BCAAs are beneficial in patients with hepatitis. Details: Preliminary clinical research in patients with alcoholic hepatitis shows that taking BCAAs 20 grams daily orally or enterally for 3 weeks or until discharge, in combination with a controlled diet, does not reduce the risk of mortality when compared with conventional protein or a controlled diet alone (37133).
Inflammatory myopathies. It is unclear if oral BCAAs are beneficial in patients with polymyositis and dermatomyositis. Details: A small clinical study in adults with suspected or confirmed polymyositis or dermatomyositis who are receiving standard corticosteroid therapy shows that a BCAA-specific product containing L-isoleucine 952 mg, L-leucine 1904 mg, and L-valine 1144 mg for 12-28 weeks, taken as two packages three times daily for a total daily dose of 24 grams, does not improve manual muscle test scores or clinical response at 12 and 28 weeks when compared with placebo (108477).
Obesity. It is unclear of oral BCAAs can reduce the likelihood of developing obesity or improve weight loss in adults with overweight or obesity. Details: Some observational research has found that higher dietary intake of BCAAs is associated with lower odds of obesity when compared with a lower intake (100466). Conversely, a large observational study in adults in Iran, including those who are overweight or obese, has found that the highest dietary intake of BCAAs is associated with a 24% higher likelihood of general obesity in males, but not in females, when compared with the lowest dietary BCAA intake (108465). This study did not report ranges for highest and lowest BCAA intake, limiting the validity of this study. BCAAs have also been evaluated in adults with overweight or obesity. A small clinical study in obese females that underwent a 4-week calorie-restricted diet shows that taking 6 caplets daily containing a total of L-leucine 3 grams, L-isoleucine 1.5 grams, and L-valine 1.5 grams in addition to vitamin B6 40 mg daily for 4 weeks does not further reduce weight, but may slightly preserve lean body mass, when compared with placebo (100464). Another small clinical study in overweight and obese adults shows that taking BCAAs 0.1 gram/kg daily in addition to starting a low-calorie diet for 16 weeks does not improve weight loss, but may preserve lean muscle mass, when compared with taking placebo while following the low-calorie diet (105583).
Overall mortality. It is unclear if dietary BCAA consumption reduces the risk of all-cause mortality. Details: Observational research in adults has found that total BCAA intake, as well as isoleucine intake, is associated with a reduced risk of all-cause mortality, particularly in those with higher serum triglyceride concentrations (108467). However, this association was not present for leucine or valine intake. The validity of this meta-analysis is limited due to unclear reporting; additionally dietary intake was recorded from a single survey.
Pancreatic cancer. The association between dietary BCAA intake and pancreatic cancer risk is unclear. Details: Observational research in adults in Italy has found that consuming BCAAs as part of the diet in quantities greater than 18 grams daily is associated with a 2-fold increased risk of pancreatic cancer when compared with less than 12 grams daily. This relationship was stronger in younger males, those with higher body mass indexes, and in those who smoke or have high alcohol intake (108476). Dietary information was recorded from a single, weekly consumption questionnaire.
Phenylketonuria (PKU). It is unclear if oral BCAAs are beneficial in patients with PKU. Details: A small clinical trial in adolescents and young adults with PKU shows that taking BCAAs, consisting of valine 150 mg/kg, isoleucine 150 mg/kg, and leucine 200 mg/kg, with meals and at bedtime for up to 6 months seems to improve attention and processing when compared with a control group (37127).
Physical performance. It is unclear if oral BCAAs are beneficial for improving physical function and muscle strength in older adults. Details: In malnourished elderly individuals, preliminary clinical research shows that taking a supplement providing BCAAs 5000 mg daily, in addition to other amino acids, vitamin B6, and vitamin B1 (Aminotrofic) for 2 months, does not improve muscle mass, muscle strength, or physical function to a greater extent than dietary advice intended to maximize nutritional intake from food and drink (103349). Similarly, a clinical study in middle aged and elderly adults shows that a specific product (Sarcojoint; Orient Euro Pharma, Inc) containing leucine 1 gram, arginine, vitamin D3, glucosamine, chondroitin, and calcium, taken twice daily in addition to regular resistance exercise for 12 weeks, does not improve muscle strength, muscle mass, or physical performance when compared with taking an unspecified vitamin B supplement twice daily with regular exercise (108472). Conversely, one small clinical study in older adults who have had a hip replacement shows that taking BCAAs 1.2 grams and lysine 1.8 grams (Amino-aile, Ajinomoto Co., Inc.) daily for one month after undergoing exercise therapy sessions modestly increases the strength of both legs and arms when compared with taking starch. However, there was no effect on hip abductor strength of the operated leg or on grip strength or measures of independence (103347).
Postoperative infection. There is limited evidence on the intravenous and oral use of BCAAs for reducing infection after oncologic surgery. Details: A meta-analysis of 6 small heterogeneous clinical trials in patients after oncologic surgery, mostly for liver cancer, suggests that receiving oral or intravenous BCAAs reduces the risk of postoperative infection by 38% when compared with control (105577).
Postoperative recovery. There is limited evidence on the intravenous and oral use of BCAAs for improving postoperative recovery after oncologic surgery. Details: A meta-analysis of small heterogeneous clinical trials in patients after oncologic surgery, mostly for liver cancer, suggests that receiving oral or intravenous BCAAs reduces hospital stay by about 2 days, but does not reduce mortality or post-operative complications, when compared with control (105577).
Psychological well-being. It is unclear if oral BCAAs are beneficial for psychological well-being. Details: A cross-sectional observational study has found that higher dietary consumption of BCAAs is associated with a lower risk of anxiety and depression when compared with lower consumption (105579).
Sarcopenia. It is unclear if oral BCAAs are beneficial in patients with primary sarcopenia or in those with sarcopenia related to liver cirrhosis. Details: A small clinical study in postmenopausal adults at risk for sarcopenia shows that consuming BCAAs 9 grams daily for 8 weeks in addition to resistance training increases strength and muscle mass when compared with baseline, but is no different than resistance training plus a placebo (105576). Another small clinical study in adults 65 years or older with sarcopenia shows that taking a supplement containing BCAAs 2500 mg, vitamin D 500 IU, protein, and other vitamins daily for 8 weeks in addition to resistance training does not improve physical function when compared with resistance training alone. The supplement did seem to slightly improve handgrip strength and body mass when compared with no supplementation (100468). However, overall the study was inadequately powered to detect smaller effects on physical function and muscle mass. There is also interest in using BCCAs in patients with sarcopenia and liver cirrhosis. A clinical study in this population shows that taking BCAAs 7.2 grams (containing 1.2 grams of L-leucine, 600 mg of L-isoleucine, and 600 mg of L-valine) daily for 6 months improves handgrip strength, gait speed, and muscle mass when compared with baseline (108468). Although the study enrolled a control group (whey protein), the investigators did not provide a statistical comparison of outcomes between groups. A separate meta-analysis of low-quality clinical research in this population shows that taking BCAAs has no effect on handgrip strength when compared with no supplementation (108473). Although other outcomes were evaluated, results are inconclusive due to the limited number of studies available for each outcome.
Spinocerebellar ataxia (SCA). It is unclear if oral BCAAs are beneficial in patients with SCA. Details: Although there is some preliminary clinical evidence that oral BCAAs might have a beneficial effect on symptoms of SCA (73), a small clinical crossover study shows that taking a particular BCAA compound (Livact) 4.5-18 grams daily for 4 weeks does not improve ataxia in patients with SCA when compared with placebo (37088).
Stroke. It is unclear if oral BCAAs are beneficial in patients recovering from stroke. Details:A small nonblinded, clinical study in elderly patients with subacute stroke and sarcopenia currently undergoing intensive inpatient rehabilitation therapy shows that administering a specific product (Seniup; Enterogenomics Co) containing BCAAs 6 grams, given twice daily orally or by feeding tube for 1 month, modestly improves skeletal muscle index, dysphagia, gait, balance, and handgrip strength, and may attenuate muscle loss in affected upper and lower extremities, when compared with rehabilitation alone (108474). The validity of these findings is limited by the short duration of treatment. Other research has compared BCAA dosing regimens. A small study in stroke patients taking part in exercise sessions shows that taking BCAAs 3.5 grams (Hepas, Clinico Co. Ltd) daily for 2 months with breakfast is more effective for improving leg strength and balance than when taken post-exercise in the mid-afternoon. However, there were no differences in most measures of strength or in skeletal muscle mass (103352). More evidence is needed to rate BCAAs for these uses.

CALCIUM

EFFECTIVE

Dyspepsia. Oral calcium carbonate is approved by the US Food and Drug Administration (FDA) as an antacid. Details: Taking calcium carbonate orally as an antacid is effective for treating dyspepsia (1843). Calcium carbonate has FDA approval as an antacid.
Hyperkalemia. Intravenous calcium gluconate is approved by the US Food and Drug Administration (FDA) for preventing hyperkalemia-induced cardiac abnormalities. Details: Administering calcium gluconate intravenously can reverse electrocardiographic changes and arrhythmias induced by hyperkalemia (12946). Intravenous calcium gluconate is FDA-approved for preventing hyperkalemia-induced cardiac abnormalities.
Hypocalcemia. Oral calcium treats and prevents hypocalcemia. Intravenous calcium is used to treat severe hypocalcemia. Details: Taking calcium orally is effective for treating and preventing hypocalcemia. Intravenous calcium gluconate, acetate, gluceptate, or chloride is effective for severe hypocalcemia or hypocalcemic tetany (12928).
Kidney failure. Oral calcium carbonate or calcium acetate is used as a phosphate binder during kidney failure. Details: Taking calcium carbonate or calcium acetate orally is effective as a phosphate binder. Calcium acetate (PhosLo) appears to control hyperphosphatemia better than sevelamer (Renagel) (12943,12944,38990). Calcium citrate is not recommended for this purpose because it increases aluminum absorption and does not bind phosphate as efficiently as calcium acetate or calcium carbonate (21631). Some clinical research also shows that taking calcium orally reduces blood pressure in patients with kidney failure (975).

LIKELY EFFECTIVE

Corticosteroid-induced osteoporosis. Oral calcium in combination with vitamin D prevents bone density loss that occurs during long-term treatment with corticosteroids. Details: Taking calcium in combination with vitamin D as adjunctive therapy seems to be effective for reducing bone mineral density loss in people using corticosteroids long-term (982,1046,1830,1831,1832,4462,4463,4464,4465,4466)(4467,12945,38493). One specific product used in clinical research is Oscal (Marion Merrel Dow Inc.), which contains elemental calcium 500 mg per tablet plus vitamin D 125 IU per tablet (982). Another product used is Oscal 250 + D (SmithKline Beecham Healthcare), which contains elemental calcium 250 mg and vitamin D 125 IU per tablet (1046).
Hyperparathyroidism. Oral calcium reduces parathyroid hormone levels in patients with secondary hyperparathyroidism due to kidney failure. Details: Taking calcium orally reduces parathyroid hormone levels in patients with kidney failure and secondary hyperparathyroidism (1827,1828,1829,39174,39425). In elderly women, the combination of calcium and vitamin D reverses secondary hyperparathyroidism and reduces hip fracture risk (8818). Also, population research suggests increased calcium intake from the diet and supplements reduces the risk of primary hyperparathyroidism in women. Supplemental intakes of at least 500 mg/day and dietary intakes of approximately 1100 mg/day are considered to be protective (91353).
Osteoporosis. Adequate calcium intake, from the diet and/or supplements, is recommended for the prevention and treatment of osteoporosis. Details: The Bone Health and Osteoporosis Foundation (BHOF) recommends ensuring adequate calcium intake in line with the recommended dietary allowance (RDA) by age, along with adequate vitamin D intake, for the prevention and treatment of osteoporosis in adults over 50 years of age. Supplementation can be used to augment dietary intake when adequate dietary intake is not feasible (109425). In the US and Canada, foods containing at least 200 mg calcium with less phosphorous content than calcium can be labelled with a health claim regarding the relationship between adequate calcium intake and a reduced risk for osteoporosis (11940,102148). However, calcium supplementation is not recommended specifically for the primary prevention of osteoporosis. The US Preventive Task Force (USPSTF) states that the current evidence is insufficient to assess the balance of benefits and harms of vitamin D and calcium supplementation, alone or in combination, for the primary prevention of fractures in community dwelling adults without osteoporosis (95695). Also, calcium supplements do not seem to be effective for preventing loss of bone mineral density (BMD) during lactation (988), in patients who have had bone marrow transplantation (1817), or in patients who have had renal transplantation (4823,38736,38871). Maximal bone growth occurs in the teenage years, and then BMD in females remains relatively constant until age 30-40. After age 40, bone loss typically occurs at rates of 0.5% to 1% per year. In males, this occurs several decades later. Bone loss is more pronounced if dietary calcium intake is below the RDA, which is the case for many Americans (2571,2578). One meta-analysis of randomized controlled trials in healthy children 7-14 years old shows that fortifying food with calcium 250-1000 mg daily for up to 24 months modestly improves femoral neck BMD, but not hip or spine BMD. However, the included trials did not supplement vitamin D (107232). During the 5 years immediately after menopause, calcium supplementation has very little effect on bone loss (2569,2570,2575,2576). The rapid loss of estrogen causes a high bone resorption rate, which increases serum calcium levels and therefore decreases intestinal absorption of calcium (2570). After this period, the typical rate of bone loss is 2% per year (2572,2576). Taking calcium 1000-1600 mg daily as carbonate, citrate, lactate gluconate, or citrate malate salt decreases this rate by 0.25% to 1% annually (977,979,981,2569,2571,2572,2575,2576,2578,6850)(38978,38980,39064). The greatest reductions (1% or more) are seen in the first 1-2 years of supplementation when bone remodeling foci can be filled (2569,2576). After this period, the differences in rate of loss between supplemented and non-supplemented females are closer to 0.25% per year (2569,2577). A meta-analysis of clinical evidence suggests that there is no additional benefit after 4 years (38980). Small clinical studies have found that continuous calcium supplementation at an average daily dose of 1050 mg, started after menopause and continued for 1.5-4 years, may reduce fracture rates by 26% when compared with no calcium supplementation. The largest of these studies was conducted in nursing home residents who also received daily vitamin D; the benefits of calcium, specifically, are unclear (39386). Some research also suggests that calcium and vitamin D improves primary prevention of osteoporotic fractures in some older individuals with osteoporosis, particularly the elderly and those who are no longer community dwelling (12930,38875,38849,39026,109471). However, not all research is positive. One large clinical trial in elderly adults with a low-trauma fracture show that taking calcium 1000 mg daily with or without vitamin D 800 IU daily for 2-7 years does not reduce the risk of a second fracture when compared with placebo (13073). Another clinical study shows that taking calcium 1000 mg daily plus vitamin D 800 IU daily does not prevent a second fracture in elderly patients, or prevent a first fracture in elderly patients with other risk factors such as low body weight (less than 58 kg, 127.6 pounds), smoking, family history of hip fracture, or fair or poor self-reported health (12929). Also, some exploratory research suggests that supplements may need to be continued indefinitely; in adults over 68 years of age, any effects of 2 years of calcium supplements on BMD appear to be lost within 2 years after discontinuing supplements (6853). Calcium has additive effects when used with other agents such as vitamin D, estrogens, or calcitonin. Whereas calcium alone generally reduces or prevents loss of BMD, combination with other agents can produce small increases in BMD ranging from 0.3% to 3.3% depending on the combination and dosages used (978,980,1836,2570,2571,2572,2576). However, one meta-analysis in healthy adults shows that fortifying foods with calcium 250-1000 mg daily, in conjunction with vitamin D supplementation, for up to 24 months does not improve BMD when compared with control (107232). The full potential of osteoporosis treatments cannot be realized without adequate calcium intake (2569,2570,2571,2572). Advise patients taking agents such as estrogens, calcitonin, bisphosphonates, or raloxifene (Evista) to ensure that their daily calcium intake meets the RDA. Use supplements if necessary. The usefulness of calcium in preventing osteoporosis in males is not as well-studied. Some observational research has found that calcium 870 mg daily is not associated with changes in BMD and bone loss in males (97201). However, clinical evidence suggests that taking calcium 1000 mg daily for 2 years might improve trabecular or cortical bone mass by 2% to 4% (980,8827,8873). Dietary supplementation with calcium and vitamin D seems to moderately reduce bone loss measured in the femoral neck, spine, and total body, and seems to reduce the incidence of nonvertebral fractures in older patients with osteopenia or low BMD (980).
Premenstrual syndrome (PMS). Adequate calcium intake seems to prevent symptoms of PMS. Details: There seems to be a link between low dietary calcium intake and symptoms of PMS (2004,6847,39007). Taking calcium 1000-1336 mg daily seems to significantly reduce depressed mood, water retention, and pain, especially if daily calcium intake is inadequate (1822,1823,1824,2004,95821). Calcium carbonate 1200 mg daily seems to decrease PMS symptom scores by about 18% when compared with placebo (1822). Increasing dietary calcium intake is also associated with a decreased risk of developing PMS. Consuming an average of 1283 mg of calcium per day from foods is associated with about a 30% lower risk of developing PMS compared with consuming an average of 529 mg daily (13094); however, taking calcium supplements does not appear to be associated with the risk of developing PMS.

Colorectal cancer. Oral calcium seems to be beneficial for preventing colorectal cancer, especially in those with adequate vitamin D levels and normal body mass index (BMI). Details: Population studies have found that increased intake of dietary or supplemental calcium is associated with a reduced risk of colorectal cancer and colorectal adenomas (1047,8820,12120,38951,98898,98899). Clinical trials and meta-analyses of clinical research also show that taking calcium supplements 1.2-2 grams daily for up to 4 years can reduce the risk of colorectal adenoma recurrence by up to 29% (970,12118,12950,15267,34596,38718,39042,95817). However, not all research has been positive. Some meta-analyses of clinical research or observational studies suggest that taking calcium does not reduce the risk of familial adenomatous polyposis or colorectal cancer (34596,39042,39349). Other contradictory research suggests that postmenopausal females who take calcium 1000 mg daily plus vitamin D 400 IU daily do not have a reduced risk of developing colorectal cancer (14290); however, this finding may not be reliable due to the high baseline intake of calcium in study participants. The reason for these conflicting findings is not entirely clear. Vitamin D might be an important factor. People with lower than average vitamin D levels do not seem to get any benefit from calcium supplements (12118). Also, one meta-analysis of previous trials suggests that taking calcium 1200 mg daily reduces the risk of colorectal adenomas in people with a normal BMI, but not in those who are overweight or obese (99715). Despite this conflicting evidence, the US Food and Drug Administration (FDA) approved a qualified health claim in 2005 stating that calcium supplements may reduce the risk of colorectal cancer and colorectal adenomas. However, the FDA has determined that there is little scientific evidence to support this claim (102366).
Fetal bone mineralization. If calcium intakes are low during pregnancy, oral calcium seems to be beneficial for increasing fetal bone density. Details: With low dietary calcium intake (less than 562 mg elemental calcium daily) during pregnancy, calcium supplementation increases fetal bone mineralization and density. However, calcium supplementation does not offer any additional benefit if calcium intakes are adequate (3263,3264).
Hypertension. Oral calcium seems to reduce blood pressure by a small amount. However, it is unclear if this reduction is clinically significant. Details: Many clinical trials and observational studies show that intake of calcium supplements or dietary calcium modestly reduces blood pressure in patients with or without hypertension, usually around 1-2 mmHg. Calcium seems to be more effective for certain subpopulations of patients, such as salt-sensitive people and patients with low baseline dietary calcium intake (945,972,974,976,984,1818,1819,1820,1821,6852)(13138,14406,38803,39063,39094,39221). Also, a meta-analysis of clinical research shows that calcium intake during pregnancy reduces systolic blood pressure in offspring by 1-2 mmHg (38852). However, a large-scale clinical trial in postmenopausal females shows that taking vitamin D (cholecalciferol) 400 IU daily in combination with elemental calcium 1000 mg daily does not lower blood pressure or reduce the risk of developing hypertension (16714). Additionally, a meta-analysis of 8 clinical trials shows that taking calcium in combination with vitamin D for up to 7 years has no effect on blood pressure (98861). The validity of this finding is limited by the poor methodological quality of the included studies. Some observational research suggests that calcium can reduce the risk for hypertension. Population research in females aged 45 years and older suggests that higher intake of calcium from both diet and supplement sources is linked to a lower risk of developing hypertension when compared to lower calcium intake (14265). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim stating that calcium supplements may reduce the risk of hypertension. However, the FDA has concluded that this claim is based on supporting, rather than conclusive, evidence (102367).
Osteomalacia. Oral calcium seems to reverse osteomalacia caused by very low calcium intakes. Details: Osteomalacia is commonly caused by vitamin D deficiency; however, very low calcium intake can also lead to osteomalacia in children and adults. Calcium supplementation can reverse osteomalacia caused by calcium deficiency. Along with appropriate vitamin D supplementation, individuals at risk of osteomalacia need sufficient calcium intake (94819).
Pre-eclampsia. Oral calcium seems to reduce the risk of pre-eclampsia in high risk pregnancies, especially if calcium intakes are low. Details: Although there is some conflicting evidence (971,38756), most clinical research shows that taking calcium orally 1-2 grams daily reduces pregnancy-related hypertension and pre-eclampsia (973,1833,8828,39043,39319,39426,96480). Calcium appears to reduce the risk of pre-eclampsia by about 50% when compared with placebo. One meta-analysis of 19 controlled trials involving over 29,000 pregnancies found that for every 19 females treated with calcium, one episode of pre-eclampsia would be avoided (96480). Calcium appears to have the greatest effect in individuals at high-risk of pre-eclampsia or with low calcium levels, and when taken at greater than or equal to 20 weeks of gestation (15029,38497,96480,99714). In 2005, the US Food and Drug Administration (FDA) approved a qualified health claim regarding the use of calcium supplements to reduce the risk of pregnancy-induced hypertension and pre-eclampsia. However, due to the limited and conflicting research available at that time, the FDA stated that this outcome was highly unlikely. Since then, large, high-quality clinical research has supported this finding. In fact, in 2016 the World Health Organization (WHO) released a recommendation to prescribe oral calcium supplementation 1.5-2 grams daily during pregnancies at high risk of pre-eclampsia if dietary calcium intakes are low, in order to prevent pre-eclampsia (97347).
Rickets. Oral calcium seems to reverse rickets caused by very low calcium intakes. Details: Rickets is commonly caused be vitamin D deficiency; however, very low calcium intake can also lead to rickets. Calcium supplementation can reverse rickets caused by calcium deficiency (94819). A small clinical study in children with nutritional rickets shows that taking calcium 500-2000 mg daily for 24 weeks improves radiographically measured rickets caused by calcium deficiency. Rickets seems to improve more rapidly with calcium 1000 mg compared to calcium 500 mg. However, increasing the calcium dose to 2000 mg daily is not more beneficial than calcium 1000 mg daily (98904).
Tooth retention. Oral calcium with vitamin D seems to help with tooth retention in the elderly population. Details: A clinical trial in the elderly population shows that taking calcium citrate malate 500 mg daily along with vitamin D3 (cholecalciferol) 700 IU daily orally for 3 years reduces the risk of tooth loss by about 52% when compared with placebo (8816).

Breast cancer. Oral calcium does not seem to be beneficial for breast cancer prevention. Details: Although some population research disagrees (15631,39041,95811,107237), most research shows that increased calcium intake is not associated with a reduced risk of breast cancer (15631,16715,98895,107236,107237). Subgroup analyses of population research suggest that calcium intake may reduce the risk of breast cancer in postmenopausal, but not pre-menopausal, adults (15631,107237). Another subgroup analysis in a large meta-analysis of population research also suggests that dietary intake may reduce estrogen receptor(ER)-negative breast cancer, but not ER-positive breast cancer (107236). However, most other research has not evaluated the effects of calcium supplementation or intake on breast cancer subtypes. The best evidence to date, from a large scale clinical trial (Women's Health Initiative), shows that taking vitamin D (cholecalciferol) 400 IU daily plus calcium 1000 mg daily for 7 years after menopause does not reduce the risk of developing invasive breast cancer at the end of the study and 5 years after the end of the intervention (16715,98895).
Fractures. Although oral calcium prevents fractures in osteoporosis, most evidence shows that calcium does NOT prevent factures in people who do not have osteoporosis. See Osteoporosis discussion for more information on the use of calcium for this purpose. Details: The most recent and robust meta-analysis of clinical research shows that calcium supplementation with or without vitamin D is NOT associated with reduced fractures in older adults without osteoporosis (95822). A large-scale study in postmenopausal females aged 50-79 years suggests calcium 1000 mg plus vitamin D 400 IU daily for 7 years only modestly improves bone mineral density (BMD) and does not significantly reduce fracture risk. This lack of effect may have been due to low adherence to the treatment regimen. In those who were 80% adherent, the combination of calcium plus vitamin D reduced the risk of hip fracture by about 29% (14282). Also, some clinical research shows that taking calcium carbonate 1000 mg and vitamin D 400 IU for 5 years does not attenuate loss of height after menopause when compared with placebo (95810). Additional meta-analyses of clinical and observational evidence suggest that calcium supplementation is not associated with a reduced risk of vertebral or nonvertebral fractures, such as hip fractures (38589,38888,98895). Some other research has suggested that calcium in combination with vitamin D reduces fracture risk in older patients without osteoporosis (980,1836,8818,12930,12933,12952,38849,102145,107235); however, this research is confounded by a number of variables, including the presence of hormonal therapy and differing levels of fracture risk at baseline (1836,8818,95822). Conflicting findings on this topic might also be due to genetic differences in patient populations. A population analysis of the Women's Health Initiative study found that, in older females with the lowest genetic susceptibility to low bone mineral density (BMD), taking calcium with vitamin D is associated with a reduction in fracture risk. However, in females with a higher genetic susceptibility to low BMD, there is no association between supplementation and fracture risk. This might be because individuals with a lower susceptibility to low BMD are also more responsive to calcium and vitamin D supplementation (97357). As of April 2018, the U.S. Preventative Services Task Force (USPSTF) concludes that there is insufficient evidence to determine whether supplementing with vitamin D >400 IU daily along with calcium >1000 mg daily is safe and effective for preventing fractures in community dwelling adults without vitamin D deficiency, osteoporosis, or a history of fracture. USPSTF recommends against supplementing with calcium 1000 mg daily or less along with vitamin D 400 IU daily or less for preventing primary fractures in community-dwelling postmenopausal females (95695).
Obesity. Oral calcium does not seem to improve weight loss. Details: Observational research has found that adults and children with low calcium intake are more likely to gain weight, have a higher body mass index (BMI), and be overweight or obese when compared to people with high calcium intake (12124,12125,12126,12127,14265). Additional observational research has found that increasing calcium intake is associated with weight loss in females; the results in males have been conflicting (12127,15602,15603). Despite these findings from observational research and a few small clinical studies (12128,15397,14438,98905), most clinical research has found that increased calcium intake does not increase weight loss (12052,13138,15396,15399,38985,39004,97356). The most recent meta-analysis of 20 clinical studies shows that daily dietary and supplemental calcium intake that meets the dietary reference intake (DRI) of 1000 mg or more daily does not increase weight loss in overweight individuals or patients with obesity when compared with intake below the DRI (95813). An older meta-analysis of 13 clinical trials also shows that increased dietary and supplemental calcium intake does not increase weight loss (15605).
Overall mortality. Oral calcium does not seem to reduce overall mortality. Details: While some population research has found that calcium taken in combination with vitamin D in older females is associated with a lower risk of death (97353), most evidence shows that calcium, with or without vitamin D, has no effect on all-cause mortality (93533,97308).

INEFFECTIVE

Cardiovascular disease (CVD). Oral calcium does not reduce the risk of developing CVD and may actually increase risk in some patients. Details: Clinical research shows that calcium does not decrease CVD risk. Several separate meta-analyses of clinical and population research involving over 50,000 patients show that taking calcium 600-1200 mg daily for up to 7 years does not reduce the risk of CVD-related outcomes, including stroke and myocardial infarction, cardiovascular death, or overall mortality (39018,91350,92994,93533,97308,98902,107231,107233). No association was found between total dietary or supplemental calcium intake with or without vitamin D and the risk of CVD or mortality (91350,93533,97308). In fact, some population and clinical research has found that when calcium is used alone or with vitamin D, there is an INCREASED risk of CVD and coronary heart disease (38077,107233). However, other clinical research disagrees (93533). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of CVD and coronary heart disease by 1.1-1.2 times when compared with control. However, the majority of the included research evaluated postmenopausal females and it is unclear if this finding is applicable to other populations (107233).
Chemotherapy-induced peripheral neuropathy. Intravenous calcium does not prevent nerve pain in patients given oxaliplatin. Oral calcium has not been evaluated for this purpose. Details: While pooled analyses of cohort studies and randomized controlled trials suggest that calcium and magnesium infusion decreases the incidence of oxaliplatin-induced neurotoxicity, a meta-analysis of only randomized controlled trials shows that the infusion has no effect in preventing neurotoxicity (90028,90029,90031). Additionally, clinical trials show that administering calcium gluconate 1 gram with magnesium sulfate 1 gram intravenously immediately before, or before and after, the administration of a single oxaliplatin cycle (90005), or over the entire 6-cycle course of oxaliplatin, does not improve symptoms of neurotoxicity when compared with placebo (96474).
Myocardial infarction (MI). Oral calcium does not prevent MI. When taken in the absence of vitamin D, oral calcium may increase the risk of MI. Details: Population research has found that increased dietary intake of calcium is associated with a decreased risk of MI (91350). However, a 2010 meta-analysis of clinical research shows that taking calcium at a dose of at least 500 mg daily is associated with an approximate 30% INCREASE in the risk of MI in patients over the age of 40. According to this analysis, one additional case of MI will occur for every 69 patients that take calcium for 5 years (17482). A more recent meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years increases the risk of MI by 1.2 times when compared with control. However, the majority of the included research studied postmenopausal females and it is unclear if this finding is applicable to other populations (107233) In contrast, other meta-analyses of clinical research have shown that taking calcium for up to 7 years is NOT associated with an increased risk of MI, including a meta-analysis that only included postmenopausal females (93533,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of MI in postmenopausal females (93533). Also, the association between calcium supplementation and MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482)

Alcohol use disorder. It is unclear if oral calcium is beneficial for alcohol use disorder. Details: Preliminary clinical research shows that taking calcium carbonate 800 mg and vitamin D 200 IU orally daily for 14 days modestly reduces alcohol craving scores and withdrawal scores when compared with placebo in adults with alcohol dependence that are undergoing withdrawal. Taking calcium carbonate did not reduce the need for diazepam; however, the study may have been inadequately powered to detect a difference between groups (107234).
Atherosclerosis. It is unclear if oral calcium is beneficial for atherosclerosis. Details: A population study has found that taking calcium 1.2 grams daily for 3 years has no effect on carotid intima thickness or carotid atherosclerosis incidence. A total calcium intake (dietary and supplemental) of at least 1794 mg daily in older females may be associated with a decreased risk of carotid atherosclerosis when compared with a total calcium intake below 1010 mg daily (97351).
Autism spectrum disorder. It is unclear if oral calcium during pregnancy is beneficial for reducing the odds of autism spectrum disorder in the offspring. Details: A small observational study found that calcium supplementation during pregnancy is associated with a 52% reduced odds of an autism spectrum disorder in the offspring (98900).
Cancer. Oral calcium alone does not seem to prevent cancer. It is unclear if oral calcium with vitamin D is beneficial for preventing cancer. Details: Taking calcium alone does not seem to significantly reduce the risk of cancer (12118,15629). The role of calcium in cancer prevention when taken along with vitamin D is controversial, as conflicting results exist. One clinical trial shows that healthy postmenopausal females who take supplemental calcium 1400-1500 mg daily plus vitamin D3 (cholecalciferol) 1100 IU daily have a 60% lower relative risk for developing cancer of any type. Approximately 25 postmenopausal females would need to take this combination for 4 years to prevent one occurrence of cancer (15629). However, a more recent clinical study shows that healthy postmenopausal females who take supplemental calcium 1500 mg daily plus vitamin D3 (cholecalciferol) 2000 IU daily do not have a reduced risk of cancer at 4 years (93943). Reasons for the disparate results are not entirely clear. The discrepancies do not appear to be related to baseline vitamin D levels or different study populations. It is possible that, given the 10-year time lapse between the two publications, the discrepancies result from differences in cancer detection capability. Also, since cancer risk was a secondary outcome measure in the earlier study and a primary outcome measure in the more recent study, it is possible that the discrepancies result from differences in statistical methodologies. The effect of vitamin D and calcium on cancer risk in males and younger patients is not known. There is also interest in using calcium for reducing the risk of hematological malignancies. An analysis of the Women's Health Initiative study shows that taking calcium 1000 mg daily in combination with vitamin D3 400 IU for up to 10 years is associated with a 20% reduction in the risk of hematologic malignancies when compared with placebo. However, no effect on hematologic malignancy related mortality was seen (97354).
Depression. It is unclear if oral calcium is beneficial for depression prevention. Details: Population research has found no association between a higher dietary intake of calcium and the risk of depression when compared with a lower dietary intake of calcium (96480).
Diabetes. It is unclear if oral calcium is beneficial for type 2 diabetes prevention. Details: Some population research has found that a higher intake of calcium from diet or supplements, alone or in combination with vitamin D, is associated with a lower risk of developing type 2 diabetes when compared with lower calcium intake (14265,16713,96473). However, population research is often limited by confounding variables. For example, one analysis found that any beneficial effect might be influenced by concomitant magnesium intake (96473). Furthermore, other population research has found that serum calcium levels higher than 9.6 mg/dL are associated with greater risk of developing diabetes in Chinese adults with osteoporosis. This study is limited because it was not determined whether increased serum calcium was due to increased calcium intake or another factor such as parathyroid function (95815).
Dysmenorrhea. It is unclear if oral calcium is beneficial for reducing pain associated with dysmenorrhea. Details: Clinical research shows that taking calcium carbonate 1000 mg with vitamin D 5000 IU daily for three menstrual cycles does not reduce pain when compared with placebo in patients with primary dysmenorrhea (95821). However, calcium carbonate 1000 mg taken alone seems to reduce pain when compared with placebo.
Endometrial cancer. It is unclear if oral calcium is beneficial for endometrial cancer prevention. Details: A meta-analysis of population research suggests that calcium supplements may reduce the risk of endometrial cancer, but dietary calcium does not seem to have any effect (38893).
Fall prevention. It is unclear if oral calcium with vitamin D is beneficial for preventing falls. Details: Research suggests that calcium in combination with vitamin D, but not calcium alone, might prevent falls by decreasing body sway and normalizing systolic blood pressure (6362,11939,39038). Some experts think the combination of calcium and vitamin D may be important (11916). Preliminary clinical research in adults residing in a health care facility shows that taking vitamin D supplements while increasing dietary calcium and protein for 2 years reduces falls by 11% when compared with standard diets. Intervention diets were supplemented with milk, yogurt, and cheese to provide calcium 1142 mg and protein 69 grams daily (107235). There might also be different effects in females compared to males. In one study, females aged 65 years or older who took vitamin D 700 IU plus calcium citrate 500 mg daily over a 3-year period had a 46% lower risk of falling. However, this combination did not decrease falls in males (14291).
Fluorosis. Oral calcium has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking calcium orally, in combination with ascorbic acid (vitamin C) and vitamin D, seems to be effective for reducing excessive fluoride levels in children and improving symptoms of fluorosis in children aged 6-12 years (990).
Heart failure. It is unclear if oral calcium in combination with vitamin D is beneficial for preventing heart failure. Details: Based on a secondary analysis of a large-scale clinical trial (Women's Health Initiative), taking calcium 1000 mg with vitamin D 400 IU daily does not reduce the risk of heart failure in the overall population or in individuals at high risk. However, in a subgroup of postmenopausal females without risk factors for heart failure, calcium and vitamin D supplementation might reduce the risk of developing heart failure by about 37% (97307).
Hypercholesterolemia. It is unclear if oral calcium is beneficial for hypercholesterolemia. Details: Some evidence shows that taking calcium carbonate 400 mg three times daily reduces low-density lipoprotein (LDL) cholesterol levels by 4% and increases high-density lipoprotein (HDL) cholesterol levels by 4% after 6 weeks of treatment when used in combination with a low-fat diet (American Heart Association Step 1) (2557). In contrast, a study in females with dyslipidemia shows that taking calcium 800 mg daily for 2 years might INCREASE total cholesterol levels by about 12 mg/dL when compared with placebo. This same study showed an association between calcium supplementation and an increase in total cholesterol levels and carotid intimal thickness in postmenopausal females, but not premenopausal females (97350). A recent meta-analysis of randomized controlled trials which included both healthy patients and patients with dyslipidemia shows that taking calcium 500-2000 mg daily and vitamin D 200-7142 IU daily modestly improves HDL cholesterol and triglyceride levels, but not LDL cholesterol levels, when compared with placebo. Subgroup analyses suggest that calcium and vitamin D supplementation is more effective in patients with dyslipidemia at baseline. It is unclear if this effect is due to calcium, vitamin D, or the combination (107227). However, other research shows that taking a specific supplement containing calcium 600 mg plus vitamin D 200 IU (Caltrate 600 D, Wyeth Consumer Healthcare Inc.) twice daily in combination with calorie restriction does not reduce total or LDL cholesterol levels when compared with placebo (15601).
Lead toxicity. It is unclear if oral calcium is beneficial for reducing blood levels of lead. Details: Lead is mobilized along with calcium from bone during pregnancy and lactation, resulting in increased serum concentrations of lead. One clinical study suggests that calcium supplementation does not significantly decrease these elevated lead concentrations (1586). However, another clinical study suggests that taking calcium reduces blood lead levels by 11% when compared with placebo, with greatest effects observed in those with high baseline levels of lead (38957).
Lyme disease. Although there is interest in using oral calcium for Lyme disease, there is insufficient reliable information about the clinical effects of calcium for this condition.
Metabolic syndrome. It is unclear if oral calcium alone or with vitamin D is beneficial for metabolic syndrome prevention. Details: Population research has found that a higher intake of calcium from diet and supplements alone, or in combination with vitamin D, is associated with a lower risk of developing metabolic syndrome when compared with lower calcium intake (14265,16713).
Nephrotic syndrome. It is unclear if oral calcium with vitamin D is beneficial for preventing nephrotic syndrome. Details: Clinical research shows that taking calcium 500-1000 mg daily for 3 months in combination with vitamin D3 60,000 IU daily or weekly for 4 weeks has no effect on bone mineral density or the risk of relapse in children with steroid-sensitive nephrotic syndrome (97355).
Nonmelanoma skin cancer. It is unclear if oral calcium is beneficial for preventing keratinocyte carcinomas. Details: In middle aged and older adults recently diagnosed with a colorectal adenoma, clinical research shows that taking calcium 1200 mg daily as calcium carbonate for 3-5 years does not reduce the incidence of keratinocyte cancer when compared with placebo over a median of 8 years. A sub-group analysis shows that taking calcium alone or with vitamin D3 1000 IU daily reduced the risk of invasive cutaneous squamous cell carcinoma by a moderate amount, but had no effect on the risk of basal cell carcinoma (104622).
Oral mucositis. When used in combination with fluoride treatments, a calcium phosphate mouth rinse seems to prevent and reduce mucositis-related pain in patients undergoing hematopoietic stem cell transplantation (HSCT). Details: A small clinical study in patients undergoing HSCT shows that using a particular mouth rinse (Caphosol, EUSA Pharma) containing calcium phosphate, in combination with fluoride treatments, reduces days of mucositis, the duration of pain, and the dose and days of morphine used when compared with placebo and fluoride treatment (38611).
Ovarian cancer. It is unclear if oral calcium is beneficial for ovarian cancer prevention. Details: An older meta-analysis of 12 cohort studies found that dietary calcium intake is not associated with a reduced risk of ovarian cancer (38792). However, a more recent pooled analysis of 15 cohort and case-control studies has found that the highest intake of dietary or dairy calcium is associated with a 20% lower risk of ovarian cancer when compared to the lowest intake (97349).
Postpartum depression. It is unclear if oral calcium is beneficial for reducing postpartum depression risk. Details: Preliminary clinical research shows that taking calcium 2 grams daily beginning at 11-21 weeks gestation reduces depression at 12 weeks postpartum when compared with placebo. However, no benefit is seen at 6 weeks postpartum (39447).
Pregnancy-related leg cramps. It is unclear if oral calcium is beneficial for preventing leg cramps during pregnancy. Details: A small clinical study shows that taking calcium 1 gram twice daily (as a mixture of salts) for 2 weeks can reduce pregnancy-related leg cramps during the second half of pregnancy when compared with no treatment (2567).
Prostate cancer. It is unclear if oral calcium is beneficial for prostate cancer prevention. Details: Some clinical research shows that taking calcium 1200 mg daily might decrease the risk of developing prostate cancer (14133). However, some epidemiological research suggests that consuming very high doses of calcium, over 2000 mg daily, might actually increase the risk of developing prostate cancer (14134). Some epidemiological research also suggests that doses greater than 1500 mg daily increase the risk of poorly differentiated, clinically advanced, and fatal prostate cancer (14132). Consumption of dairy products has also been weakly linked to a modest increase in risk of prostate cancer (98894). However, contradictory research suggests that there is no association between dietary intake of calcium and overall risk of prostate cancer (14131,14132,104630).
Stroke. It is unclear if oral calcium is beneficial for stroke prevention. Details: Some population research has found that increasing dietary calcium intake is associated with a decreased risk of ischemic stroke (4822,38678). However, other population research has found that increasing dietary calcium intake is not associated with a decreased risk of stroke (91350). One meta-analysis of high-quality randomized controlled trials shows that taking calcium for 2-7 years does not affect the risk of stroke when compared with control. However, the majority of the included research evaluated postmenopausal females, and it is unclear if this finding is applicable to other populations (107233).
Vertigo. Oral calcium with vitamin D might reduce positional vertigo; the effect of calcium when used alone is unclear. Details: A large clinical study in adults with recurrent benign paroxysmal positional vertigo shows that taking calcium 500 mg and vitamin D 400 IU twice daily for one year reduces annual recurrence of vertigo by 27% when compared with no treatment. The number needed to treat to prevent vertigo was 3.7 (103681). It is unclear if this benefit is due to vitamin D, calcium, or the combination. More evidence is needed to rate calcium for these uses.

EFFECTIVE

Sickle cell disease. A specific oral glutamine powder (Endari, Emmaus Medical, Inc) is approved by the US Food and Drug Administration (FDA) to reduce acute complications of sickle cell disease. Details: Clinical research in adults and children 5 years of age and older shows that taking glutamine 5-15 grams (0.3 grams/kg body weight) orally twice daily for 48 weeks, either with or without hydroxyurea, delays the median time to first crisis by 30 days, and reduces the incidence of acute chest syndrome by 15%, number of hospitalizations by 33%, and the number of hospitalized days by 40%, when compared with placebo (96519,99414).

Burns. Oral glutamine seems to improve healing in patients with severe burns and may also reduce the risk for burn wound infections; however, it is unclear if glutamine improves hospitalization length or mortality. Details: Some clinical research shows that administering enteral nutrition supplemented with glutamine 0.35-0.5 grams/kg daily for 12-14 days, beginning within 24-48 hours of hospitalization for severe burn injury (excluding inhalation injury), decreases the length of hospital stay by 6-9 days and may shorten wound healing when compared to control enteral nutrition (52307,52337). A clinical study in adults with moderate to severe burns (including inhalation injury) shows that administering enteral nutrition supplemented with intravenous alanyl glutamine 0.5 grams/kg daily, beginning within 24 hours of burn injury and continued for 14 days, may improve burn-induced organ damage, particularly intestinal mucosal injury, but does not improve mortality or length of hospitalization, when compared with standard nutritional support (108027). Another study in the same population shows that administering enteral nutrition supplemented with glutamine 4.3 grams every 4 hours, beginning within 24 hours of burn injury, decreases the risk of mortality by 83% and the risk of Pseudomonas wound infections; however, it does not decrease the duration of hospitalization (52311). A meta-analysis of these trials and one additional trial shows that administering glutamine enterally reduces the risk of Gram-negative bacterial wound infections by 73% and reduces the risk of mortality by 87% when compared to a control group. However, there was no difference in length of stay or overall wound infection rate (97363). Results were based on a small number of patients within each outcome evaluation. Intravenous glutamine has also been evaluated. One small clinical study shows that intravenous glutamine 0.57 grams/kg daily decreases the incidence of Gram-negative bacteremia by 35% when compared with control in patients with severe burns. However, it does not appear to decrease the incidence of Gram-positive bacteremia, the need to use antibiotics, or risk of mortality (52272).
Critical illness (trauma). Oral and intravenous glutamine seem to reduce infectious complications in critically ill adults. However, glutamine does not seem to reduce mortality in this population. Details: Some studies show that glutamine reduces the risk of infectious complications in critically ill, multiple-trauma, or postoperative adult patients (5449,5450,7309,7731,8184,52288,52359). However, other studies show no benefit (52308,52360,97362). Meta-analyses of these and other clinical trials suggest that glutamine supplementation reduces the risk of nosocomial infections in critically ill patients by 15% to 18% and the risk of nosocomial infections in surgical patients by 30% to 41%. This benefit was seen only with parenteral glutamine; enteral glutamine does not appear to reduce the risk for nosocomial infection (91355,91358). The role of glutamine for reducing mortality in critically ill adults is conflicting. Some clinical trials suggest that glutamine-enriched enteral and parenteral nutrition reduces mortality in critically ill patients (52283,52289,52408). However, other studies show no benefit (52288,52308,52354,52359,97362). Meta-analyses of results from these and other clinical trials show that, overall, taking glutamine does not reduce the risk of mortality in critically ill patients (91355,91358). However, the dose and dosage form may affect outcomes. One meta-analysis shows that glutamine does not affect the risk of mortality when administered at doses up to 0.5 grams/kg daily, although doses greater than 0.5 grams/kg daily may INCREASE mortality by 18% (91355). Another meta-analysis shows that glutamine decreases short-term mortality in critically ill patients by 25% when administered parenterally, but not enterally (91358). Neither parenteral nor enteral glutamine appears to decrease the risk of long-term mortality in critically ill patients (91358). Research evaluating glutamine in critically ill children is limited. One clinical study in children ages 1-17 admitted to an intensive care unit (ICU) shows that enteral administration of glutamine along with zinc, selenium, and intravenous metoclopramide does not reduce nosocomial infections when compared with whey supplementation (86095).
HIV/AIDS-related wasting. Oral glutamine seems to attenuate weight loss related to HIV/AIDS. Details: Very small clinical studies show that taking glutamine orally seems to enhance intestinal absorption of nutrients, decrease intestinal permeability, and increase weight gain in adults with HIV/AIDS when compared with placebo. Doses of 40 grams daily seem to produce the greatest effect (2337,2702). Lower doses of 14 grams daily might also be effective when used in combination with arginine and hydroxymethylbutyrate (a leucine metabolite) (7310).
Postoperative recovery. Oral or intravenous glutamine seems to reduce the duration of hospitalization and improve postoperative nutritional status in adults. However, it does not seem to reduce postoperative mortality. Details: Although some conflicting evidence exists (52316), most clinical research shows that receiving free glutamine or glutamine-containing dipeptide intravenously decreases the duration of hospitalization after surgery, particularly after major abdominal surgery (2363,5448,7300,7732,52275,52341). A meta-analysis of this research and other studies shows that IV supplementation with glutamine-containing dipeptides reduces the length of hospital stay by 3 days when compared with no supplementation (96507). Other meta-analyses of clinical research also show that glutamine supplementation, as free glutamine or glutamine-containing dipeptides, reduces the risk of hospital-acquired infections by 30% in surgical intensive care unit (ICU) patients and by 41% in elective surgical patients (91355,91358). In cancer patients undergoing abdominal surgery, glutamine-supplemented parenteral nutrition seems to improve nutritional status and gastrointestinal function (100943). Glutamine-containing dipeptides also appear to help to preserve intestinal integrity (7299,7300,7732,52306). One small study has evaluated oral glutamine 10 grams, in combination with arginine 4.5 grams, in patients undergoing surgery for enterocutaneous fistulas. This study shows that taking this combination daily for 7 days prior to surgery reduces recurrence of fistulas by 35%, and also reduces postoperative infections (103837). Although glutamine seems to decrease length of stay and reduce infection rate, it does not appear to reduce the risk of mortality in either surgical ICU or elective surgical patients (91355,91358,96509,103834), including those receiving major abdominal surgery (5448,52316,91355,96507). Additionally, most research shows that glutamine supplementation does not reduce the incidence of infectious complications following abdominal surgery (52306,52316,52341,5448,7300,96507). The effects of glutamine on reducing infection rate might be related to patient population, modes of nutrition, or dose of glutamine. Taking a combination of glutamine 7 grams, arginine 7 grams, and hydroxymethylbutyrate 1.2 grams (Abound, Abbott) orally daily for 3 days before and 7 days after abdominal surgery does not reduce the incidence of wound infections or other complications (99413). Most of the research evaluating glutamine in surgical patients has been conducted in adults. Information in children is limited. Existing clinical research shows that glutamine-fortified parenteral nutrition does not improve intestinal permeability, nitrogen balance, duration of hospitalization, incidence of infectious complications, or risk of mortality in newborns and infants undergoing digestive-tract surgery (52338,96508).

Athletic performance. Oral glutamine does not seem to improve athletic performance. Details: Small studies in trained athletes or healthy adults show that taking glutamine orally does not seem to enhance performance or immune response during intense acute or prolonged exercise when compared with placebo (2341,2342,5455,5456).
Crohn disease. Oral glutamine does not seem to improve symptoms of this condition. Details: Small clinical studies in adults and children with Crohn disease show that taking glutamine 7 grams three times daily or following a glutamine-enriched diet for 4 weeks does not seem to improve intestinal permeability or disease activity, and might even worsen disease activity, when compared with placebo or a low-glutamine diet (2338,6256).
Cystinuria. Oral glutamine does not seem to improve cystinuria. Details: According to case reports, taking glutamine orally does not seem to reduce the excretion of cysteine in the urine in patients with homozygous cystinuria (2339).
Low birth weight. Oral glutamine does not seem to reduce adverse consequences of low birth weight in infants. Details: Most clinical studies show that glutamine supplementation does not improve the time to full enteral feeding, infant growth rate, or length of hospital stay in low birth weight infants (52305,52312,52325,52342,52362,52410). One follow-up study also shows that neonatal glutamine supplementation is not associated with improvements in cognitive function, motor skills, or behavior outcomes by school age when corrected for neonatal infection rate (52342,97365).
Muscular dystrophy. Oral glutamine does not seem to improve symptoms of Duchenne muscular dystrophy. Details: Clinical studies show that taking glutamine 0.5-0.6 grams/kg orally does not significantly improve muscle strength or whole body protein degradation in children with Duchenne muscular dystrophy when compared with placebo or a nonspecific amino acid mixture (46657,52363).
Prematurity. Oral glutamine does not seem to reduce morbidity or mortality associated with prematurity. Details: A meta-analysis of clinical trials in preterm infants, including infants with low to very low birth weight, shows that use of enteral or parenteral glutamine does not reduce the risk of mortality or morbidities, such as necrotizing enterocolitis, when compared with control. However, limited evidence from a sub-group analysis suggests that enteral glutamine might modestly reduce the risk of invasive infection when compared with control (105015). These findings are limited by the selection bias and heterogeneity of the included trials.
Radiation-induced diarrhea. Oral glutamine does not seem to improve diarrhea due to radiation therapy. Details: One meta-analysis of five randomized, controlled trials shows that taking oral glutamine during radiotherapy for pelvic cancers does not prevent or reduce the severity of diarrhea when compared with placebo (97367).

Antiretroviral-associated diarrhea. It is unclear if oral glutamine improves diarrhea caused by antiretroviral agents. Details: A small crossover clinical study in HIV patients shows that oral glutamine 30 grams daily for 10 days seems to reduce the severity of nelfinavir-associated diarrhea when compared with placebo (52313).
Alcohol use disorder. Although there is interest in using oral glutamine for alcohol use disorder, there is insufficient reliable information about the clinical effects of glutamine for this condition.
Attention deficit-hyperactivity disorder (ADHD). Although there is interest in using oral glutamine for ADHD, there is insufficient reliable information about the clinical effects of glutamine for this condition.
Chemotherapy-induced diarrhea. It is unclear if oral glutamine improves diarrhea caused by chemotherapy. Details: Although preliminary clinical studies show that glutamine might reduce the occurrence of chemotherapy-induced diarrhea (7235,7285), a meta-analysis of this research and others shows no difference in the severity of diarrhea (7233,7295,96516). Despite results showing a significant 1-day reduction in the duration of diarrhea, this might not be considered clinically significant (96516).
Chemotherapy-induced lymphocytopenia. It is unclear if oral glutamine reduces lymphocytopenia caused by chemotherapy. Details: One small clinical study in patients with esophageal cancer receiving chemo-radiotherapy shows that taking glutamine 30 grams daily for 28 days seems to prevent a reduction in lymphocytes when compared with placebo (2705). However, another small clinical trial in patients with leukemia or lymphoma receiving intensive chemotherapy shows that adding glutamine 26 grams to total parenteral nutrition (TPN), in place of other amino acids, does not affect duration of neutropenia when compared with receiving an isonitrogenous standard TPN (7295).
Coronavirus disease 2019 (COVID-19). It is unclear if oral glutamine is beneficial in patients hospitalized with COVID-19 pneumonia. Details: A very small, nonblinded, non-randomized evaluation of otherwise healthy patients over 50 years of age who were hospitalized with mild COVID-19 pneumonia shows that taking glutamine 10 grams three times daily orally with meals is associated with a 1-day decrease in hospital stay (from 10 days to 9) when compared with patients not taking glutamine. In the latter group, 4 patients required transfer to the ICU, compared with no patients in the glutamine group (103839). A similar, non-randomized evaluation of adults hospitalized with COVID-19 pneumonia shows that adding the same dose of glutamine to other therapies for 5 days is associated with a 3-day decrease in hospital stay (from 14 days to 11) when compared with patients not taking glutamine. At the end of treatment, 0% of patients in the glutamine group required ICU services, compared with 54% of patients who did not receive glutamine. This study also shows that taking glutamine may increase appetite (108035). The validity of these findings is limited by short duration of treatment and use of non-standardized treatments.
Cystic fibrosis. It is unclear if oral glutamine improves growth and development in children with cystic fibrosis. Details: A small clinical study in undernourished or stunted children with cystic fibrosis shows that taking glutamine 0.7 grams/kg daily orally for 4 weeks with or without recombinant human growth hormone (rhGH) does not promote protein gain when compared with rhGH alone (52321).
Diabetic foot ulcers. Oral glutamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a specific nutritional supplement drink containing glutamine 7 grams, arginine 7 grams, and hydroxymethylbutyrate 1.5 grams (Abound, Abbott) twice daily for 16 weeks does not improve total wound closure or reduce the time to complete healing when compared with a control drink in patients with diabetic foot ulcers (96637). It is unclear if this effect is due to glutamine, other ingredients, or the combination.
Diarrhea. It is unclear if oral glutamine improves diarrhea in children and infants. Details: One preliminary clinical study in 6-24 month-old otherwise healthy children with acute diarrhea shows that taking capsules prepared with a specific glutamine powder (Power Glutamine, Champion Nutrition) 0.3 grams/kg daily for 7 days reduces the duration of diarrhea by about one day when compared with placebo (52323). However, other clinical research in male infants 1-12 months old with acute diarrhea and dehydration shows that adding glutamine 90 mmol/L along with the standard World Health Organization oral rehydration salts (ORS) does not decrease the duration of diarrhea, stool output, or the volume of oral rehydration solution required to achieve and maintain hydration when compared with standard ORS alone (7298).
Hematopoietic stem cell transplant (HSCT). It is unclear whether oral glutamine or glutamine added to parenteral nutrition improves morbidity and mortality in patients undergoing HSCT. Some research has suggested that intravenous glutamine may actually worsen outcomes. Details: Some research suggests that patients receiving glutamine-supplemented parenteral nutrition (PN) after HSCT primarily to treat hematologic malignancies have a diminished incidence of clinical infections, lower rates of microbial colonization, and decreased length of hospital stay when compared to control (2366,52381). However, not all patients seem to benefit. Some research shows that oral glutamine or PN with glutamine does not reduce the risk of mortality or infections in patients with hematologic malignancies and/or solid tumors (5451,52385). Also, a small clinical study in patients undergoing HSCT shows that PN with glutamine dipeptide may increase the duration of hospital stay (52292). Furthermore, one small study has found that receiving PN with glutamine was associated with lower disease-free survival and event-free survival over 3 years when compared with standard PN in patients receiving HSCT for hematologic malignancies (52355).
Irritable bowel syndrome (IBS). There is limited evidence on the oral use of glutamine in patients with IBS. Details: A clinical trial in adults with IBS (diarrhea-predominant, constipation-predominant, mixed, or alternating bowel habits) shows that following a low FODMAP diet supplemented with oral glutamine 15 grams three times daily for 6 weeks improves IBS-Severity Scoring System (IBS-SSS) scores, with 88% of patients in the glutamine group reporting a 45% improvement in severity scores, compared with 60% of patients following the low FODMAP diet alone (108037). The validity of this finding is limited by short duration of treatment and lack of follow-up. Preliminary clinical research in patients with postinfectious, diarrhea-predominant IBS shows that taking glutamine 5 grams three times daily for 8 weeks leads to a nearly 14-fold greater likelihood of symptom improvement, defined as a reduction of 50 points or more on the IBS-SSS, and decreases stool frequency by 2.45 stools daily when compared with placebo. Taking glutamine also seems to reduce abdominal pain ratings by 55% and improve quality of life scores by 53% when compared to baseline in these patients (100944). The validity of these findings is limited by the lack of a comparator group.
Lung cancer. It is unclear if oral glutamine improves survival in patients with advanced lung cancer. Details: One small clinical study in patients with advanced non-small cell lung cancer shows that taking glutamine 10 grams three times daily for 12 months along with palliative chemoradiotherapy prevents weight loss, which is an important predictor of survival, but does not increase the likelihood of progression-free survival when compared with palliative chemoradiotherapy alone (100942). It is unclear if this study was adequately powered to detect a difference in survival between groups.
Malnutrition. It is unclear if oral alanyl-glutamine improves height and weight in children at risk for malnutrition. Details: Preliminary clinical research in children aged 2 months to 5 years from a low-income area of Brazil and at risk for malnutrition, shows that taking 3-12 grams of alanyl-glutamine orally daily for 10 days improves gut integrity and is associated with a modest, short-term increase in weight when compared with a glycine placebo (103838).
Exercise-induced muscle damage. It is unclear if oral glutamine is beneficial for exercise-induced muscle damage. Details: A very small clinical crossover trial in professional athletes undergoing rigorous training shows that taking oral glutamine 6 grams daily for 20 days reduces serum levels of creatine kinase and myoglobin when compared with placebo (108031). The validity of these findings is limited due to the small size and short duration of treatment.
Obesity. It is unclear if oral glutamine is beneficial for weight loss. Details: A preliminary clinical study in 36 overweight or obese adults shows that taking glutamine 30 grams daily for 2 weeks reduces waist circumference by 1.8 cm, but does not improve body weight, body mass index, or glycemic indices, when compared to baseline. None of these outcomes were improved over baseline in an alanine control group (100941). Given the small study size and short duration of therapy, the long-term effects of glutamine on anthropometric measures is unclear.
Opioid withdrawal. Oral glutamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in Chinese patients undergoing detoxification from heroin shows that taking a combination of tyrosine, lecithin, 5-HTP, and glutamine 50 mg/kg orally daily for 6 days might reduce mood-related withdrawal symptoms when compared with placebo (88178). It is unclear if this effect is due to glutamine, other ingredients, or the combination.
Oral mucositis. There is contradictory evidence about the effects of glutamine in patients with, or at risk of developing, oral mucositis from chemotherapy or radiotherapy. Details: Small clinical studies suggest that taking glutamine orally or swishing and swallowing a glutamine solution can decrease the incidence, severity, and duration of oral mucositis in some patients undergoing chemotherapy and/or radiation therapy for cancer or hematopoietic stem cell transplant (HSCT) (2336,2368,2704,5029). Additionally, three meta-analyses of highly heterogeneous clinical trials in patients with cancer receiving chemotherapy and/or radiation therapy suggests that glutamine reduces the incidence of severe (grade ≥3) oral mucositis when compared with control (105014,108028,108036). These analyses are limited for several reasons, including reporting bias, lack of sensitivity analysis, and population heterogeneity. Some small clinical studies included in these meta-analyses suggest that supplementation with glutamine may reduce the need for feeding tubes and opioid analgesics (108028,108036). However, not all research has been positive. Some small clinical studies in patients receiving chemotherapy with 5-fluorouracil for cancer or HSCT suggest that oral or intravenous glutamine does not reduce the incidence of oral mucositis when compared with control (2365,5451,5462,7296,52349,52350). Furthermore, a meta-analysis of 5 clinical trials in patients with head or neck cancers shows that oral glutamine does not reduce the overall incidence or the incidence of moderate to severe radiation-induced oral mucositis when compared with control (103836). The Multinational Association of Supportive Care in Cancer and the International Society for Oral Oncology (MASCC/ISOO) cautiously recommends the use of oral glutamine to prevent oral mucositis in patients with head and neck cancer receiving chemoradiotherapy. However, due to some evidence suggesting that intravenous glutamine may actually worsen outcomes in HSCT patients, the MASCC/ISOO recommends against its use for the prevention of oral mucositis in patients receiving high-dose chemotherapy, with or without total body irradiation, for HSCT (105004).
Paclitaxel-induced myalgia and arthralgia. It is unclear if oral glutamine reduces the risk for myalgias and arthralgias due to paclitaxel. Details: One small clinical study shows that taking glutamine 10 grams three times daily for 5 days, starting on the day of chemotherapy and repeated over 2 cycles of chemotherapy, does not reduce the rate or severity of paclitaxel-induced myalgias or arthralgias when compared with placebo (52331).
Pancreatitis. It is unclear if oral glutamine improves outcomes in patients with acute pancreatitis. Details: Two meta-analyses of the available clinical research in patients with pancreatitis show that enteral or parenteral supplementation with glutamine increases albumin, decreases C-reactive protein, and might reduce mortality, multiple organ dysfunction syndrome, hospital length of stay, and infections. Results are difficult to interpret due to the significant heterogeneity of the included trials and limited generalizability of the results (96513,103835).
Peptic ulcers. Although there is interest in using oral glutamine for peptic ulcers, there is insufficient reliable information about the clinical effects of glutamine for this condition.
Postoperative infection. It is unclear if oral or intravenous glutamine is beneficial for the prevention of postoperative infection in patients with colorectal cancer who are recovering from surgery. Details: A meta-analysis of nonblinded clinical research in adults with colorectal or colon cancer who recently underwent radical surgery shows that daily supplementation with glutamine 0.3-1 grams/kg, administered either orally or parenterally, improves the rate of surgical site infections and anastomotic leakage when compared with control (108033). These findings are limited by the high heterogeneity of the included studies and unclear reporting.
Postoperative recovery. It is unclear if oral or intravenous glutamine is beneficial in patients with colorectal cancer who are recovering from surgery. Details: A meta-analysis of nonblinded clinical research in adults with colorectal or colon cancer who recently underwent radical surgery shows that taking either oral or parenteral glutamine 0.3-1 grams/kg daily may reduce the length of hospital stay when compared with control (108033). These findings are limited by the high heterogeneity of the included studies and unclear reporting.
Pressure ulcers. Oral glutamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A very small clinical study in patients with stages II-IV pressure ulcers shows that taking a specific nutritional supplement drink containing glutamine 7 grams, arginine 7 grams, and hydroxymethylbutyrate 1.5 grams per packet (Abound, Abbott Nutrition) as two packets twice daily by mouth for 2 weeks has no effect on wound area or healing scores by the Pressure Ulcer Scale for Healing (PUSH) measurement when compared with standard nutritional care (96506).
Radiation dermatitis. It is unclear if oral glutamine reduces the risk of developing dermatitis from radiation therapy. Details: One small clinical study in patients with head and neck cancers receiving cisplatin shows that taking a specific supplement containing glutamine 7 grams, arginine 7 grams, and hydroxymethylbutyrate 1.5 grams (Abound, Abbott) orally twice daily, starting on day 1 of radiation and continuing until 1 week after radiation therapy, does not reduce the incidence of severe radiation-induced dermatitis when compared with no supplementation (96639). However, another small clinical study in patients with breast cancer who have had both chemotherapy and surgery shows that taking oral glutamine 5 grams three times daily, starting 1 week before radiation and continuing until 1 week after radiation, is associated with a reduction in grade 1 and grade 2 radiation dermatitis when compared with placebo (97366).
Radiation-induced esophagitis. It is unclear if oral glutamine reduces the risk of developing esophagitis from radiation therapy. Details: A small clinical study in patients with advanced non-small cell lung cancer shows that taking glutamine 10 grams three times daily for 12 months along with a palliative dose of chemoradiotherapy (total 30 Gy) results in a 7% incidence of symptomatic (grade 2 or higher) radiation-induced esophagitis, compared with a 53% incidence with palliative chemoradiotherapy alone. The glutamine group also had a 5.8-day delay in the onset of esophagitis (100942). However, a lower dose of glutamine in patients receiving higher doses of radiotherapy might not be beneficial. A small clinical study in patients with advanced thoracic malignancies shows that taking glutamine 4 grams mixed in water twice daily for 4 weeks along with radiotherapy (total dose of at least 45 Gy) to the esophagus, with or without chemotherapy, does not slow the onset of radiation-induced esophagitis or reduce its severity when compared with a glycine placebo (105011).
Short bowel syndrome. It is unclear if oral glutamine improves symptoms of short bowel syndrome. Details: Although small clinical studies suggest that glutamine plus growth hormone can decrease dependence on parenteral nutrition in some patients (2334,2361,2362,2703), it has not shown benefit for improving intestinal absorption of energy in all studies (8185). Additionally, glutamine alone doesn't appear to be beneficial (7730).
Traumatic Brain injury (TBI). It is unclear if intravenous glutamine is beneficial in patients hospitalized with severe TBI. Details: A clinical trial in patients hospitalized for a severe TBI shows that adherence to a hypocaloric, low-protein diet supplemented with daily intravenous glutamine 0.3 g/kg for 7 days does not improve 28-day mortality when compared with standard nutritional support alone. However, it may reduce the length of ventilator use, hospitalization, and duration of intensive care unit stay (108034).
Vincristine-induced neuropathy. It is unclear if oral glutamine reduces the risk of developing neuropathy from treatment with vincristine in children. Details: Preliminary clinical research in children ages 1-21 years receiving vincristine for various cancer types shows that taking glutamine 6 grams/m2 twice daily orally for 21 days reduces sensory neuropathy when compared with placebo. There was a significant improvement in self-reported, but not parent-reported, quality of life scores as measured by the PedsQL scale. However, there was no effect on motor neuropathy with the use of glutamine (96517).
Wound healing. It is unclear if oral glutamine improves wound healing. Details: Preliminary clinical research in trauma patients with wound healing disorders shows that taking glutamine 20 grams orally daily in combination with ascorbic acid 500 mg, vitamin E 166 mg, beta-carotene 3.2 mg, selenium 100 mcg, and zinc 6.6 mg (Glutamine Plus, Fresenius Kabi) for 14 days reduces the time to wound closure by 29 days when compared with placebo. However, there is no difference in length of stay (97364). More evidence is needed to rate glutamine for these uses.

Cholera. Oral L-histidine seems to reduce diarrhea in adults with cholera. Details: A clinical study in adults with severe cholera receiving ciprofloxacin shows that drinking a rice-based oral rehydration solution (CeraLyte-90, CERA products) supplemented with L-histidine (Ajinomoto Chemical) 2.5 grams per liter as needed for 72 hours decreases the frequency of stool output at 32 hours, the weight of stool at 72 hours, the amount of intravenous fluid needed during the first 48 hours, and the duration of diarrhea by roughly 5 hours when compared with drinking the oral rehydration solution alone (96312).

Atopic dermatitis (eczema). It is unclear if oral L-histidine is beneficial in adults and children with atopic dermatitis. Details: A small clinical crossover study in adults with atopic dermatitis shows that taking L-histidine 4 grams daily for 8 weeks improves clinician-reported disease severity scores by 32% to 34% when compared with baseline (108621). The lack of washout period prior to crossover and its subsequent carryover effect prevents useful statistical comparison to placebo, limiting the validity of these findings. A small clinical study in children aged 1-7 years with mild to moderate atopic dermatitis shows that taking L-histidine 0.8 grams daily for 12 weeks improves disease severity by 49% when compared with baseline (108652). The lack of statistical comparison to the placebo group limits the validity of these findings.
Kidney failure. It is unclear if oral L-histidine is beneficial for anemia in patients with kidney failure. Details: A small clinical study in patients with chronic uremia and patients undergoing maintenance hemodialysis shows that taking L-histidine 4 grams daily does not improve anemia when compared with placebo (2352).
Metabolic syndrome. It is unclear if oral histidine is beneficial in patients with metabolic syndrome. Details: A clinical study in females with obesity and metabolic syndrome shows that taking histidine 2 grams twice daily is associated with reduced insulin resistance, body mass index, waist circumference, and fat mass at 12 weeks when compared with placebo. It is unclear if the improvement from baseline differed between groups. Other lipid parameters were not affected (96311).
Rheumatoid arthritis (RA). It is unclear if oral L-histidine is beneficial in patients with RA. Details: A small clinical study in patients with RA shows that taking L-histidine 4.5 grams daily for 30 weeks does not improve clinical measurements when compared with placebo (2350). More evidence is needed to rate histidine for these uses.

Sarcopenia. Oral HMB seems to increase muscle mass and may attenuate muscle loss in older adults. However, it may not offer additional benefit when used in conjunction with exercise. Details: Meta-analyses of clinical research as well as individual clinical studies in healthy older adults, including those at risk for sarcopenia, show that HMB supplementation increases muscle mass or fat-free mass when compared with placebo or other control (96645,106027,108771). Furthermore, some clinical research in elderly people with a recent hip fracture who are undergoing rehabilitation shows that a specific liquid nutritional supplement (Ensure Plus Advance, Abbott) providing the calcium salt of HMB (Ca-HMB) 1.5 grams, calcium 500 mg, and calcidiol 500 IU, taken twice daily in addition to standard therapy, attenuates muscle loss, but does not affect function, when compared with standard therapy alone (96640). HMB has also been evaluated in combination with exercise. In a meta-analysis subgroup of healthy, older adults, HMB supplementation combined with exercise did not result in additional increases in fat-free mass when compared with supplementation alone (106027). Similarly, in an individual clinical study in older females at risk for sarcopenia, HMB supplementation did not enhance the effects of exercise on fat-free mass when compared with exercise alone (108770).

Physical performance. Oral HMB, when taken in conjunction with participation in an exercise regimen, does not seem to improve physical performance in older adults. Details: Most clinical research in elderly patients shows that HMB is not beneficial for improving overall physical performance (99245,99249,102869). A meta-analysis of 10 clinical studies in patients 50-80 years of age shows that taking HMB along with physical exercise does not improve muscle strength, physical performance measures, or body composition when compared with physical exercise alone (102869). Conversely, a small clinical study in older adults shows that taking the calcium salt of HMB (Ca-HMB) along with vitamin D for 12 months improves a composite functional index of physical performance at 6 and 12 months, but not at 3 and 9 months, when compared with control. The addition of moderate resistance exercise training 3 times weekly did not further improve the composite functional index among those receiving supplementation (106026).

Athletic performance. It is unclear if oral HMB, alone or in combination with other ingredients, is beneficial for improving performance in athletes at various levels. Details: A small clinical study in elite male rowers shows that taking HMB 1 gram three times daily for 12 weeks increases aerobic capacity and peak anaerobic power when compared with placebo. It also increases the maximum volume of oxygen consumed, compared with a small decrease following intake of placebo. However, anaerobic adaptation does not seem to be improved (99246). HMB has also been evaluated in combination with other ingredients. A small clinical study in adolescent, middle-distance runners aged 14-17 years shows that supplementation with a specific calcium salt of HMB (Ca-HMB) (HMB 1250 Mega Caps, Olimp Laboratories) 2.5 grams along with L-arginine alpha-ketoglutarate (AAKG 1250 Extreme Mega Caps, Olimp Laboratories) 2.5-3.75 grams, taken 3 times daily, attenuates reductions in countermeasure jump height during a 12-day intensive training camp when compared with placebo (106032). Conversely, a very small clinical study in male collegiate rugby players shows that supplementation with HMB along with creatine monophosphate for 6 weeks does not improve maintenance of performance and body composition when compared with creatine monophosphate alone (106031). Changes in markers of muscle damage and stress were similar between groups in both studies (106031,106032).
Cachexia. Oral HMB has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A small clinical study in patients with cancer-related cachexia shows that taking HMB 3 grams daily in combination with arginine 14 grams and glutamine 14 grams daily in two divided doses for up to 24 weeks increases body weight and lean body mass by about 1 kg, compared with reduced body weight and lean body mass in those taking placebo (52280). Conversely, a small clinical study in patients with cachexia due to rheumatoid arthritis (RA) shows that taking this combination for 12 weeks does not improve body weight or lean body mass when compared with placebo (52340).
Cirrhosis. It is unclear if oral HMB is beneficial in patients with liver cirrhosis. Details: A small clinical study in patients with liver cirrhosis shows that taking HMB 3 grams daily for 12 weeks improves muscle mass and some measures of muscle function when compared with baseline (108768). The lack of statistical comparison to placebo limits the validity of these findings. Additionally, it should be noted that the groups were unmatched at baseline in terms of cirrhosis etiology and liver frailty index.
Critical illness (trauma). It is unclear if a calcium salt of HMB (Ca-HMB) can reduce muscle wasting in critically ill adults. Details: A small clinical study in patients with severe critical illness receiving mechanical ventilation shows that taking Ca-HMB 1.5 grams twice daily, beginning on day 4 of admission and continuing for 10-30 days, does not reduce muscle wasting when compared with placebo (108769).
Diabetic foot ulcers. Oral HMB has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A clinical study in patients with diabetic foot ulcers shows that drinking a specific beverage (Juven/Abound, Abbott Nutrition) containing HMB 1.2 grams, L-arginine 7 grams, and L-glutamine 7 grams twice daily for 16 weeks does not improve wound healing when compared with placebo (96637).
Exercise-induced muscle damage. It is unclear if oral HMB is beneficial for reducing exercise-induced muscle damage. Details: A small clinical study in resistance trained males shows that taking a free acid form of HMB (HMB-FA) 1 gram prior to a high-volume resistance training session, and then 2 grams in divided doses later that day, attenuates an increase in creatine kinase levels when compared with placebo. Also, perceived recovery 48 hours after exercise was approximately 38% higher than placebo (99250). Conversely, a very small clinical study in elite male rowers shows that taking HMB 3 grams within 30 minutes after each training session and 30 minutes before bed on non-training days for 10 weeks does not reduce markers of exercise-induced muscle damage, including aspartate aminotransferase, lactate dehydrogenase, and creatine kinase, when compared with placebo (102871).
Exercise-induced muscle soreness. Small clinical studies suggest that oral HMB does not improve exercise-induced muscle soreness in trained and untrained males. Details: One small clinical study in resistance-trained males shows that taking a specific free acid form of HMB (HMB-FA) (Clear Muscle, Muscle Tech) or a specific calcium salt of HMB (Ca-HMB) (HMB, Millennium Sport Technologies, Inc.) 1 gram three times daily for 12 weeks does not improve participant ratings of delayed onset muscle soreness when compared with placebo (102872). Another small clinical study in untrained males participating in a resistance training program shows that taking HMB 3 grams daily for 2-4 weeks prior to resistance training does not reduce muscle soreness when compared with placebo (102873).
HIV/AIDS-related wasting. Oral HMB has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A small clinical study in patients with AIDS-related wasting shows that taking HMB 3 grams in combination with arginine 14 grams and glutamine 14 grams daily in two divided doses for 8 weeks seems to increase body weight and lean body mass and possibly improve immune function when compared with placebo (1909).
Kidney failure. It is unclear if oral HMB reduces the incidence of complications in patients with kidney failure receiving maintenance hemodialysis. Details: A small clinical study in patients on maintenance hemodialysis shows that taking HMB 3 grams daily for 6 months does not affect body composition, bone density, muscle strength, or physical function, when compared with placebo (99255). The validity of this study is limited by its small size and low rate of adherence.
Malnutrition. It is unclear if an oral calcium salt of HMB (Ca-HMA) is beneficial in patients with, or at risk of, malnutrition. Details: A large clinical trial in older, community-dwelling adults at medium to high risk for malnutrition who are receiving dietary counseling shows that taking an oral nutrition supplement containing Ca-HMB 0.74 grams twice daily results in achievement of the goal outcome in 33% of patients, compared with 9% of those receiving placebo. The goal outcome was a composite of survival without hospital admission or readmission and at least 5% weight gain at 6 months. Ca-HMB supplementation also resulted in significant improvements in various nutritional and functional outcomes (106028). A retrospective study in patients with or at risk of malnutrition receiving dietary and exercise counseling shows that supplementation with an oral nutrition supplement(Ensure Plus Advance, Abbott Nutrition) containing Ca-HMB 1.5 grams twice daily for 3-6 months seems to improve anthropometrics and body composition when compared with baseline (108772). The validity of this finding is limited by the lack of statistical comparison to those taking a standard oral nutrition supplement.
Muscle strength. The benefits of HMB for improving muscle strength seem to depend on the physical fitness of the individual. Although small clinical studies suggest HMB may be modestly beneficial in untrained adults, most research has shown no benefit in trained adults. Details: A meta-analysis of 11 studies in a mixed population of both trained and untrained healthy adults shows that HMB does not increase muscular strength outcomes or improve body composition when compared with placebo (106030). However, research in specific populations suggests that benefits may differ depending on baseline training level. Most research in previously untrained individuals seems to show that HMB offers a modest benefit on muscle strength (11003,96642,96643). Some preliminary clinical research shows that HMB might increase strength and body composition and reduce muscle damage when used during resistance training or intense endurance exercises (1929,2168,10062,55821,102873). A meta-analysis of clinical studies in mostly untrained males shows that taking HMB 3 grams daily can modestly increase lean body mass by 0.3% and strength by 1.4% weekly (21446). Another meta-analysis assessing untrained weightlifters shows that taking HMB results in small increases in upper body strength, but not lower body strength, when compared with control (96642). Another small clinical study in untrained males participating in a 12-week training program not included in the above meta-analyses shows that taking calcium HMB 1 gram three times daily does not increase muscle strength or reduce fat mass, but might increase fat-free mass in the legs, when compared with placebo (102870). Conversely, most research in trained athletes shows that salt formulations of HMB do not increase muscle strength, improve body composition, or reduce muscle damage (2167,55820,55825,55826,55831,96638,96641,96643,102872,102874). A small clinical study in resistance trained males shows that taking HMB 1 gram three times daily for 9 weeks does not increase muscle strength or lean mass overall, but does increase lower body strength by approximately 9%, when compared with placebo (99251). However, this finding has not been supported in other research in previously trained athletes (96642). Research using the free acid form of HMB (HMB-FA) has shown some benefit in previously trained males. A small clinical study in this population shows that taking HMB-FA 1 gram three times daily for 12 weeks increases muscle strength approximately three-fold when compared with placebo. There is also an approximate 90% prevention of muscle strength loss during a two-week overtraining phase when compared with placebo, as well as improvements in lean body mass and muscle power (99248).
Muscle fatigue. It is unclear if oral HMB is beneficial for reducing muscle fatigue in trained males. Details: A small clinical study in trained males shows that taking a free acid form of HMB, 3 grams as a single dose, prior to a muscle damage protocol returns work capacity to pre-exercise levels within 24 hours, compared with more than 72 hours with placebo. However, there was no effect on other measures of muscle recovery (99253).
Obesity. It is unclear if oral HMB is beneficial for reducing abdominal adiposity. Details: A small clinical study in elderly males shows that taking HMB 1.5 grams twice daily for 12 weeks while undergoing a resistance training program reduces abdominal adiposity by approximately 9.5% when compared with either the resistance exercise program alone, HMB alone, or placebo (99247). Another small clinical study in postmenopausal adults with overweight or obesity shows that taking a specific product (Abound, Abbott) containing a calcium salt of HMB (Ca-HMB), L-arginine, and L-glutamine twice daily for 4 weeks reduces visceral adipose tissue by 94 grams, compared with an increase of 60 grams in those taking placebo (108773). It is unclear if this effect is due to HMB, the other ingredients, or the combination.
Oral mucositis. Oral HMB has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A small clinical study in patients with head and neck cancer undergoing chemoradiotherapy shows that taking a specific product (Abound, Abbott) containing HMB 1.2 grams, arginine 7 grams, and glutamine 7 grams in water twice daily during treatment does not reduce the incidence of moderate to severe functional changes from oral mucositis when compared with baseline (99243). The validity of this finding is also limited by the lack of a comparator group and the use of subjective measures.
Postoperative recovery. Oral HMB has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A small clinical study in patients with abdominal malignancies shows that taking a specific product (Abound, Abbott) containing HMB 1.2 grams, arginine 7 grams, and glutamine 7 grams in water once daily for ten days, starting three days prior to surgery, does not reduce the incidence of wound complications or length of hospitalization when compared with placebo (99413).
Radiation dermatitis. Oral HMB has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A small clinical study in patients with head and neck cancer undergoing chemoradiotherapy shows that taking a specific product (Abound, Abbott) containing HMB 1.2 grams, L-arginine 7 grams, and L-glutamine 7 grams in water twice daily, starting on the first day of chemoradiotherapy and continuing for up to 1 week after completing therapy, does not reduce the incidence of grade 3 dermatitis when compared with control (96639). More evidence is needed to rate HMB for these uses.

EFFECTIVE

L-carnitine deficiency. Oral and intravenous L-carnitine can treat primary and secondary L-carnitine deficiency. Details: Administering L-carnitine orally or intravenously is effective for acute or chronic treatment of primary L-carnitine deficiency or secondary L-carnitine deficiency due to inborn errors of metabolism. This is an FDA-approved indication for L-carnitine (4949,58611,59018). For primary or secondary deficiencies, oral L-carnitine 990 mg 2-3 times daily is used. For inborn errors of metabolism resulting in secondary L-carnitine deficiency, L-carnitine 50 mg/kg given as a slow (2-3 minute) bolus injection or by infusion followed by 50 mg/kg administered in divided doses every 3-4 hours over the next 24 hours is also used. Subsequent daily maintenance doses of intravenous L-carnitine are usually around 50 mg/kg (3616).

Angina. Oral and intravenous L-carnitine may improve exercise tolerance and symptoms of angina during exercise in patients with angina. Details: Several small clinical trials in patients with chronic stable angina or cardiac syndrome X show that taking L-carnitine orally or intravenously seems to improve exercise tolerance and time to onset of angina when compared with placebo (3623,3624,58156,59096,59118,59216,59217,59230). Oral doses of L-carnitine have ranged from 900 mg to 2 grams daily in single or divided doses for 2 weeks to 6 months (3623,3624,58156,59096,59118,59217). Intravenous L-carnitine 3 grams in 500 mL of 5% dextrose, administered once daily for 14 days (59230), or intravenous DL-carnitine 40 mg/kg administered 30 minutes prior to exercise (59216) have also been used.
Congestive heart failure (CHF). Oral and intravenous L-carnitine may improve exercise capacity and symptoms of heart failure in patients with CHF. Details: Several small clinical trials in patients with CHF show that taking L-carnitine 1.5-3 grams daily in single or divided doses for up to 34 months or administering intravenous L-carnitine 5 grams daily for 7 days seems to improve symptoms and increase exercise capacity when compared with placebo (3625,3626,58145,58771,58824). Also, taking a specific combination product containing L-carnitine 2250 mg and coenzyme Q10 270 mg (Carni Q-Gel, Tishcon Corporation) daily for 12 weeks appears to improve symptoms of CHF when compared with no treatment (58392).
Hyperlipidemia. Oral or intravenous L-carnitine may slightly improve lipid levels. Oral, but not intravenous, L-carnitine may also improve lipoprotein(a) levels in patients with elevated lipoprotein(a). Details: Most meta-analyses of clinical research in patients with or without hyperlipidemia show that L-carnitine, given orally at a dose of 76 mg to 3 grams daily or intravenously at a dose of 15-20 mg/kg three times weekly, appears to reduce total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglyceride levels by up to 9.5 mg/dL, 8.3 mg/dL, and 11.2 mg/dL, respectively, while increasing high-density lipoprotein (HDL) cholesterol by up to 1.6 mg/dL. Sub-analyses in patients with elevated levels of specific lipids shows that L-carnitine might be most beneficial in these populations (95073,102019,111886). However, clinical research is generally very low to moderate quality. Also, any effects of L-carnitine on these lipids are modest and might not be considered clinically significant. An umbrella meta-analysis of meta-analyses of clinical research shows that taking L-carnitine orally reduces total cholesterol, LDL cholesterol, and triglyceride levels by only 1.1 mg/dL, 4.8 mg/dL, and 2.5 mg/dL, with increases in HDL cholesterol of 0.7 mg/dL (111896). More information is needed on the effects of L-carnitine on lipid levels specifically in patients with hyperlipidemia. Some research has also evaluated the benefits of L-carnitine in people with hyperlipidemia and elevated lipoprotein(a) levels or those undergoing hemodialysis. Preliminary clinical research and a meta-analysis of clinical research in these populations shows that taking L-carnitine 1-2 grams daily for 8-24 weeks reduces levels of lipoprotein(a) by about 9 mg/dL when compared with control (58155,95073). However, giving L-carnitine intravenously 1 gram three times weekly or 4 grams daily does not improve lipoprotein(a) levels in these patients (95073). Also, oral or intravenous L-carnitine does not improve LDL cholesterol, HDL cholesterol, or triglyceride levels in these patients (58155,95073). Whether L-carnitine reduces the risk of cardiovascular events in patients with hyperlipidemia is unknown.
Kidney failure. Intravenous, but not oral, L-carnitine is FDA-approved for the prevention and treatment of L-carnitine deficiency in patients with kidney failure undergoing hemodialysis. Any other benefits with the use of L-carnitine in patients on hemodialysis are unclear. Details: Patients with kidney failure undergoing maintenance hemodialysis often experience L-carnitine deficiency, which can lead to lipid, red blood cell, cardiac muscle, and skeletal muscle abnormalities (26496). Use of intravenous L-carnitine for the prevention and treatment of L-carnitine deficiency in people with kidney failure who are undergoing hemodialysis is an FDA-approved indication for L-carnitine. L-carnitine 10-20 mg/kg is given as a slow (2-3 minute) bolus injection, with dose adjustments made based on subsequent pre-dialysis L-carnitine concentrations (3616). However, oral L-carnitine is not FDA-approved for this purpose. There is concern that long-term administration of high doses of oral L-carnitine may result in accumulation of toxic metabolites, including trimethylamine and trimethylamine-N-oxide, in patients with kidney failure (3616). Research in other areas are conflicting. Most clinical research shows that taking L-carnitine 0.7-3 grams or 10 mg/kg daily or administering L-carnitine 2-6 grams or 30-60 mg/kg weekly via intravenous infusion can improve cardiac function, intravenous fistula complications, red blood cell count, hemoglobin, and C-reactive protein levels in patients on hemodialysis (9790,26496,58257,58437,58842,59009,59178,111877). A meta-analysis of 18 clinical studies in adults with kidney-related anemia undergoing hemodialysis shows that receiving oral or intravenous L-carnitine reduces erythropoietin responsiveness and erythropoiesis stimulating agent (ESA) requirement, but not hemoglobin level, when compared with placebo or conventional therapy, regardless of treatment duration or route of administration (107406). Despite an earlier meta-analysis suggesting that L-carnitine does not reduce the incidence of dialysis-related hypotension or muscle cramping (58511), a more recent meta-analysis shows that L-carnitine reduces the incidence of dialysis-related hypotension by 74% when compared with placebo (111878). However, sub-analyses suggest that only oral L-carnitine, and doses of over 4.2 grams weekly for at least 12 weeks, are effective for preventing hypotension (111878). A meta-analysis and some preliminary clinical research also show that muscle cramping is reduced by up to 78% when compared with controls (104176,111878). Additionally, observational research has found that administering at least 1 gram of L-carnitine per dialysis session for at least 10 sessions monthly is associated with a 10% to 20% decrease in the number of hospitalization days during the subsequent month (58409). However, L-carnitine may not be beneficial for improving other measures in people with kidney failure receiving dialysis. While some research shows that L-carnitine decreases lipoprotein(a) levels (44187), low-density lipoprotein (LDL) cholesterol levels (26496,91723,107399), and total cholesterol levels (107399), most research shows that it does not improve serum lipid levels (9790,26496,44187,58257,58320,58842,58939,59009,59025,59031)(59036,59059,59080,90633,91723,107399). Additionally, while one small clinical trial shows that taking L-carnitine can improve performance on some exercise tests (104179), most research shows that L-carnitine does not improve respiratory function or exercise performance. The effect on quality of life is unclear (58154,58437,58472,58743,59031,90633,111867,111877).
Male infertility. Oral L-carnitine, taken alone or in combination with acetyl-L-carnitine, may increase sperm motility in males with infertility, leading to a greater likelihood of pregnancy in female partners. Details: Although some clinical research has yielded conflicting results (58209,58588,59020,90627,111861), most clinical research shows that taking L-carnitine 1-3 grams daily in divided doses for up to 24 weeks, with or without acetyl-L-carnitine 1 gram daily, increases sperm count and motility, and improves sperm morphology, in males with infertility of various etiologies (12352,58167,58182,58194,58334,58469,58831,58849,59129,59189)(59190,101560,107394,111861,111459,111888,111890). However, it is unclear if taking L-carnitine increases the odds of pregnancy. One meta-analysis of randomized controlled trials shows that taking L-carnitine and acetyl-L-carnitine in combination increases the odds of pregnancy by 3.7-fold over placebo. However most clinical research investigating the effect of L-carnitine alone or with acetyl L-carnitine on pregnancy rates disagrees (12352,58182,101560,111861,111459,111888). The number of studies investigating the effect of L-carnitine alone or with acetyl-L-carnitine on pregnancy rate is small and the duration of supplementation may be inadequate. Taking L-carnitine 1 gram and acetyl-L-carnitine 0.5 grams twice daily after taking nonsteroidal anti-inflammatory drugs for 2 months seems to increase sperm count and motility in males with abacterial prostatovesiculoepididymitis, an inflammation of the prostate gland, seminal vesicles, and epididymis (9791). Some studies have also evaluated L-carnitine in combination with other ingredients. One clinical trial in males with asthenospermia shows that taking L-carnitine 150 mg, acetyl-L-carnitine 50 mg, L-arginine 1660 mg, and Panax ginseng 200 mg daily for 3 months increases sperm motility and sexual satisfaction when compared with no treatment (32189). Another small clinical trial shows that taking this combination along with prulifloxacin 600 mg daily for 6 months improves sperm concentration and motility when compared with prulifloxacin alone in patients with chronic prostatitis due to Chlamydia trachomatis infection (59006). Other small and preliminary clinical studies have investigated the effects of a specific combination product providing L-carnitine 1 gram twice daily for 6 months, along with acetyl-L-carnitine, coenzyme Q10, selenium, zinc, vitamin C, folic acid, vitamin B12, and citric acid (Proxeed Plus). Taking this combination product has been shown to improve measures of sperm quality such as sperm count, sperm concentration, total motility, and progressive motility when compared to baseline. The effect on sperm volume and morphology is unclear. Most research has been conducted in patients with oligoasthenozoospermia, although some benefit has also been shown in patients with varicocele-related infertility, especially those with more severe varicocele (102017,107395,111296). The validity of these findings is limited by the lack of comparator group. Also, it is unclear if these effects are due to L-carnitine, other ingredients, or the combination. The effect of L-carnitine in combination with other ingredients on pregnancy rate has also been examined. One meta-analysis of moderate-quality clinical research shows that taking L-carnitine in combination with micronutrients increases the odds of pregnancy by 3.5-fold over placebo or no treatment (111888).
Myocarditis. Oral DL-carnitine may prevent myocarditis in children with diphtheria. Details: Myocarditis is a complication of diphtheria. Clinical research in children with diphtheria shows that taking DL-carnitine 100 mg/kg daily for 4 days reduces the risk of myocarditis and mortality when compared with no treatment (3620,3621).
Valproic acid-induced toxicities. Although more well-designed research is needed to confirm these findings, oral and intravenous L-carnitine may improve neurologic and hepatic function and reduce ammonia levels in patients with these valproic acid-induced toxicities. Details: Valproic acid-induced toxicities are often associated with low plasma and tissue levels of L-carnitine. Preliminary clinical research and case reports in patients on valproic acid therapy who have neurologic or hepatic deterioration or hyperammonemia show that taking L-carnitine 50-100 mg/kg daily in divided doses or administering L-carnitine 150-500 mg/kg daily via intravenous infusion seems to improve neurologic and hepatic function and bring plasma ammonia levels within normal limits (1438,1914,1915,1916,1917,4523,5798,5799,95068). There is also some preliminary evidence that intravenous L-carnitine can prevent the development of severe valproic acid-induced hepatotoxicity when given to patients being treated for overdose and accidental ingestion of valproic acid (1438,4528,5798,5799), especially if treatment is initiated early (4528). Despite these results, most evidence consists of anecdotal individuals or small case series. A more recent retrospective cohort study suggests that treatment with an L-carnitine dosing regimen consisting of a 100 mg/kg intravenous loading dose followed by up to 3 grams daily in divided doses for 3 days or until ICU discharge does not enhance valproic acid elimination or prevent organ dysfunction when compared with patients not treated with L-carnitine (111869). Also, taking L-carnitine does not appear to reduce valproic acid-associated weight gain (58295). Well-designed clinical trials are still needed to determine the role of L-carnitine in the treatment or prevention of valproic acid toxicities.

Acne. Topical L-carnitine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical trial in patients with mild-to-moderate acne shows that applying a proprietary formulation containing L-carnitine, licochalcone, and 1,2-decanediol to the face twice daily for 8 weeks reduces the number of acne lesions and pustules and improves quality of life when compared to baseline. However, the improvements do not appear to be significant when compared with placebo (26493).
Age-related fatigue. Small clinical studies suggest that oral L-carnitine may improve physical and mental fatigue associated with aging. Details: Two small clinical trials in elderly patients experiencing fatigue after slight physical activity shows that taking L-carnitine 2-4 grams daily for 1-6 months improves physical and mental fatigue, increases muscle mass, and decreases fat mass when compared with placebo (16109,16111).
Aluminum phosphide poisoning. It is unclear if intravenous L-carnitine is beneficial in people with aluminum phosphide poisoning. Details: A meta-analysis of preliminary clinical research in patients with aluminum phosphide poisoning shows that intravenous L-carnitine does not reduce the odds of mortality when compared with control groups receiving routine treatments only (111892). However, only 2 studies were included in the analysis and both studies may have been underpowered to detect differences.
Alzheimer disease. Oral L-carnitine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with mild to moderate Alzheimer disease shows that taking L-carnitine tartrate 3.73 grams, in combination with serine, nicotinamide riboside, and N-acetyl cysteine, daily for 28 days and then twice daily for 56 days does not improve cognitive function when compared with taking placebo. However, in patients with the most severe symptoms, there was some modest improvement (110623). This study may have been underpowered to detect differences. Also, the effect of L-carnitine alone is unclear.
Androgenic alopecia. It is unclear if topical L-carnitine is beneficial in people with androgenic alopecia. Details: One small clinical trial in individuals with androgenic alopecia shows that applying topical L-carnitine 2% solution to the scalp twice daily for 6 months significantly increases the number of terminal hair shafts on the scalp when compared with placebo (58390).
Anorexia nervosa. Although there has been interest in using oral L-carnitine for anorexia nervosa, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose.
Anthracycline cardiotoxicity. Oral and intravenous L-carnitine have only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in patients with breast cancer undergoing doxorubicin treatment shows that taking a combination of L-carnitine and vitamin E over 4 21-day treatment cycles decreases the proportion of patients with cardiac events by 24.2% when compared with chemotherapy treatment only. There were also modest beneficial effects on some enzyme measures of cardiac health. Patients received L-carnitine 3 grams intravenously on the first day of each cycle followed by an oral intake of 300 mg 4 times daily for the remaining 20 days. Vitamin E 1800 mg daily was taken orally in 3 divided doses (111891).
Athletic performance. Oral L-carnitine has been evaluated for its effect on athletic performance in several small and short-term clinical studies, with mixed results. Details: Maximal exercise in trained athletes has been associated with a decrease in plasma L-carnitine levels (3648,58583). Theoretically, restoring these levels with L-carnitine supplementation might have beneficial effects. However, clinical studies examining the use of L-carnitine for athletic performance have reported conflicting results. Some clinical studies show that taking L-carnitine 2 grams, either before exercise or daily for up to 6 weeks, enhances athletic performance and endurance and reduces post-exercise muscle pain in male athletes and healthy untrained males (58450,59182,59185), but other studies do not support these findings (1947,59128,59134). Additionally, although some studies show that taking L-carnitine 1-2 grams or 40 mg/kg before exercise or 4 grams daily for 2 weeks can decrease lactate accumulation and increase oxygen uptake, power output, and time to anabolic threshold during exercise (3649,3650,59061,59184,59186), other studies show no improvement in these outcomes (58471,58775,59033,59045,59069,59128). These discrepancies may be related to the small study sizes, short treatment durations, and variable dosing regimens.
Atrial fibrillation. It is unclear if oral L-carnitine is beneficial for preventing postoperative atrial fibrillation in patients undergoing aortic valve surgery. Details: A very small clinical study in patients undergoing aortic valve replacement or valve-sparing aortic root replacement shows that receiving oral L-carnitine (L-Cartin FF, Otsuka Pharmaceutical) 1 gram three times daily, beginning 2 days prior to surgery and continuing for 7 days after surgery, is associated with a postoperative atrial fibrillation rate of 20%, compared with a rate of 60% in a historical age-matched control group not receiving L-carnitine (107408).
Attention deficit-hyperactivity disorder (ADHD). It is unclear if oral L-carnitine is beneficial in children with ADHD. Details: One small crossover trial in children with ADHD shows that taking L-carnitine 50 mg/kg twice daily for 6 months improves parent and teacher assessments of behavior when compared with placebo (58166).
Autism spectrum disorder. Small clinical studies suggest that oral L-carnitine may improve some symptoms of autism spectrum disorder. Details: Small clinical trials in children 3-16 years of age with autism spectrum disorder show that taking L-carnitine 50 mg/kg or 150 mg/kg daily for 8 to 12 weeks modestly improves overall symptoms of autism, especially lethargy, social isolation, hyperactivity, and irritability, when compared with taking placebo. However, there is inconsistency between studies with respect to rating scales used and specific endpoints showing improvement. In one study, children remained on any pre-existing medications; in the other two, all children were also taking risperidone (58981,111887,111900).
Arrhythmia. Small clinical studies suggest that oral L-carnitine may reduce the incidence of arrhythmias in patients with premature ventricular contractions. Details: Small clinical trials in patients with premature ventricular contractions show that taking L-carnitine 2 grams twice daily for 45 weeks or 2 grams three times daily for 2 weeks might reduce the incidence of arrhythmias when compared to baseline (59043,59120,59143).
Asthenopia (eye strain). Oral L-carnitine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in videoterminal users with computer vision syndrome and without dry eye shows that taking a product containing L-carnitine 50 mg, along with zinc and extracts of elderberry, black currant, and eleuthero root (Meramirt CM) daily for 1 month modestly reduces severity of eye strain and sensitivity when compared with not taking this product (111295). It is unclear if these findings are due to L-carnitine, other ingredients, or the combination.
Beta-thalassemia. Small clinical studies suggest that oral L-carnitine may improve symptoms and reduce complications of beta-thalassemia minor, intermedia, and major. Details: Several small clinical trials in children with beta-thalassemia major show that taking L-carnitine 50 mg/kg daily for 3-6 months might reduce pulmonary artery systolic pressure, increase cardiac output during exercise, and improve progression to puberty (58294,58502,58556). Clinical research in adults with beta-thalassemia intermedia shows that taking L-carnitine with hydroxyurea appears to increase hemoglobin and hematocrit and reduce left ventricular end-diastolic diameter, a measure of pulmonary hypertension (58679). In patients with beta-thalassemia major or intermedia aged 6 years and up, taking L-carnitine 50 mg/kg daily for 6 months normalized left ventricular dilatation and hypertrophy in 30% and 37% of patients, respectively, compared with only 10% in those taking placebo. Cardiac output was also improved, but there were no changes in blood parameters (101565). Clinical research in children with beta-thalassemia minor shows that taking L-carnitine 50 mg/kg daily, with or without folic acid 1 mg daily, for 3 months appears to reduce bone pain by 84% to 87% and increase the number of climbable stairs 3.1- to 5.2-fold when compared with baseline (90631).
Cachexia. Small clinical studies suggest that oral L-carnitine may improve body composition and quality of life in patients with cancer-related cachexia. Details: One small clinical trial in patients with cancer-related cachexia shows that taking L-carnitine 4 grams daily for 12 weeks increases body mass index (BMI) when compared with placebo (59029). Other research shows that taking L-carnitine 4 grams daily with megestrol acetate, eicosapentaenoic acid (EPA), and thalidomide for 5 months is more effective than any single product alone for increasing lean body mass in patients with cancer-related cachexia (23437). Additionally, taking L-carnitine 4 grams daily with megestrol acetate, celecoxib, and antioxidants for 4 months appears more effective than megestrol acetate alone for improving lean body mass, fatigue, and quality of life in these patients (59012).
Cancer-related fatigue. It is unclear if oral L-carnitine is beneficial for improving fatigue in patients with advanced cancer. Details: Some cancer patients have low blood levels of L-carnitine, which may reduce energy production and lead to fatigue. Some small clinical trials in patients with advanced cancer show that taking L-carnitine 3-4 grams daily for 7 days significantly improves some measures of fatigue when compared to baseline (16106,16110). However, other higher quality clinical research shows that taking L-carnitine 2-4 grams daily for 4-12 weeks is no more effective than placebo for improving fatigue in advanced cancer patients (26498,58523,59029).
Celiac disease. It is unclear if oral L-carnitine is beneficial in patients with celiac disease. Details: Some research shows that L-carnitine blood levels are low in patients with celiac disease. One small clinical trial in patients with celiac disease shows that taking L-carnitine 2 grams daily for 6 months lowers some measures of fatigue when compared with placebo. However, L-carnitine does not significantly improve measures of depression or quality of life in these patients (16105).
Chemotherapy-related fatigue. It is unclear if oral L-carnitine is beneficial in patients with fatigue due to sunitinib therapy. Details: A small clinical study in adults with renal cell carcinoma who are experiencing fatigue associated with sunitinib treatment shows that taking L-carnitine 1500 mg daily for 2 weeks modestly improves fatigue severity when compared to baseline (100352). The validity of this finding is limited by the small study size and lack of a comparator group.
Chronic fatigue syndrome (CFS). It is unclear if oral L-carnitine is beneficial in patients with CFS. Details: One small clinical study in adults with CFS shows that taking L-carnitine 1 gram three times daily for 2 months can improve some symptoms of CFS when compared to baseline (3630). The validity of this finding is limited by the lack of a comparator group.
Chronic obstructive pulmonary disease (COPD). It is unclear if oral L-carnitine is beneficial in patients with COPD. Details: One small clinical study in adults with moderate to severe COPD shows that taking L-carnitine 2 grams daily for 6 weeks improves exercise performance and walking tolerance when compared with placebo (58213).
Cirrhosis. Preliminary research suggests that oral L-carnitine may be beneficial in patients with cirrhosis. Details: One small clinical trial in patients with cirrhosis who are receiving branched-chain amino acids supplements to improve nutritional status shows that taking L-carnitine 1 gram orally daily for 6 months, in addition to increasing exercise by 2000 steps per day, does not improve muscle volume, handgrip strength, or leg strength, but does reduce complaints of muscle cramping, when compared to baseline (102124). Another small, uncontrolled clinical trial in patients with cirrhosis shows that taking L-carnitine 1800 mg daily for 6 months does not improve Child-Pugh scores, but may improve quality of life, when compared to baseline (104177). The validity of these studies is limited by the lack of comparator groups. The effect of L-carnitine has also been examined retrospectively in patients with cirrhosis. One retrospective study in matched patients that had been admitted to hospital for cirrhosis suggests that taking L-carnitine for more than 30 days is associated with an increase in survival length by about 21 months compared with not taking L-carnitine. Overall, L-carnitine use was also associated with a 36% to 48% increase in the proportion of patients surviving 1-5 years, with the greatest effect in patients with modest to severe liver dysfunction. The median dose of L-carnitine was 1000 mg daily for at least 6 months is associated with a reduced loss of skeletal muscle compared with not taking L-carnitine (111860). The validity of these studies is limited by their retrospective design.
Cognitive function. It is unclear if oral L-carnitine is beneficial for improving cognitive function in healthy individuals. Details: Low-quality clinical research shows that taking L-carnitine 500 mg as a single dose or 250 mg twice daily for 3 days does not improve cognitive function or memory in otherwise healthy young adults when compared with placebo (58176,95070).
Coronary heart disease (CHD). It is unclear if oral L-carnitine is beneficial in patients with CHD. Details: One small clinical trial in patients with CHD shows that taking L-carnitine 2 grams prior to exercise does not improve endurance when compared with placebo (58196). Another small clinical trial in patients with CHD shows that taking L-carnitine 1 gram daily for 12 weeks does not improve low-density lipoprotein (LDL) cholesterol, total cholesterol, or apolipoprotein-B when compared with placebo; however, it does appear to increase high-density lipoprotein (HDL) and apolipoprotein A-1 levels in these patients (95071).
Coronavirus disease 2019 (COVID-19). It is unclear if oral L-carnitine is beneficial for COVID-19 prevention or treatment. Details: Preliminary clinical research in patients hospitalized with mild to moderate COVID-19 shows that taking L-carnitine 1 gram 3 times daily for 5 days does not reduce the incidence of fever or cough when compared with standard treatments only. However, all patients taking L-carnitine survived compared with 86% of those given standard treatment only. Also, there were improvements in oxygen saturation and inflammatory measures (111874). Other clinical research in patients with confirmed asymptomatic or mild COVID-19 shows that taking L-carnitine tartrate (Carnipure) 1 gram 3 times daily for 21 days does not prevent the development of severe lung symptoms when compared with taking placebo. However, in a sub-group of patients, lung lesion improvement was significantly better between days 7 and 14. In adults without COVID-19 but living with someone with confirmed disease, taking this product does not prevent COVID-19 when compared with taking placebo. However, the total number of confirmed illnesses in the population was low (111898).
Critical illness (trauma). It is unclear if oral or nasogastric L-carnitine is beneficial for critical illness. Details: One small clinical trial in critically ill patients in the ICU shows that receiving L-carnitine (BSK, Zist Takhmir Co, Tehran-Iran) 3 grams daily via a nasogastric tube for 7 days modestly improves disease severity, organ function, inflammatory and other laboratory measures when compared with receiving placebo. Also, mortality rate was reduced by approximately 50%. There was no effect on the duration of hospital or ICU stay (111883,111884). However, another small clinical trial in critically ill patients following an acute ischemic stroke shows that oral or nasogastric L-carnitine tartrate 500 mg every 8 hours for 6 days does not affect the duration of mechanical ventilation or hospital or ICU stay, the severity of illness, or 28-day mortality rates, when compared with taking placebo. There was a modest beneficial effect on insulin resistance (111881). This study was small and may have been underpowered to detect differences.
Diabetes. Oral L-carnitine may improve glycemic control in patients with diabetes, but it is unclear if these improvements are clinically meaningful. It is also unclear if L-carnitine can improve lipid profiles or weight loss in these patients. Details: While individual study results are mixed (58169,58189,58514,58793,90632,96922,101561), meta-analyses of available clinical research in mixed populations shows that taking L-carnitine 200 mg to 4 grams daily reduces fasting plasma glucose and glycated hemoglobin (HbA1C) levels, and possibly insulin, and improves insulin resistance, when compared with taking placebo or a control diet, although the clinical significance of these improvements is unclear (102018,111875,111886). One meta-analysis shows that these benefits are generally specific to patients with high levels of fasting glucose, diabetes, or obesity, as well as studies investigating L-carnitine in doses of at least 2 grams daily for 12 weeks. However, a small number of studies included in this analysis investigated the effects of acetyl-L-carnitine (111875). Other research in obese patients with type 2 diabetes shows that, when taken with orlistat or sibutramine, L-carnitine 2 grams daily for 12 months decreases body weight and body mass index and improves glycemic control when compared with orlistat or sibutramine alone (58778,58830,58882). The effect of L-carnitine on lipids in people with diabetes is unclear. Some studies show significant reductions in total cholesterol, low-density lipoprotein cholesterol, triglycerides, and/or lipoprotein(a) (58554,58647,58649,90632,101561,107397), while other studies show no improvement in lipid profiles (58169,58189).
Dilated cardiomyopathy. Small clinical studies suggest that oral L-carnitine may improve ejection fraction in children with dilated cardiomyopathy and adults with ischemic cardiomyopathy. Details: Primary L-carnitine deficiency is a common cause of pediatric dilated cardiomyopathy. Additionally, patients with dilated cardiomyopathy of unknown etiology have been shown to have low cardiac levels of L-carnitine (59196,100351). Due to these findings, L-carnitine has been evaluated for the treatment of dilated cardiomyopathy in children and adults, but the small sizes of these studies and methodological limitations limit the reliability of the results. One small clinical study in children under 13 years of age with dilated cardiomyopathy shows that taking L-carnitine 50-100 mg/kg daily for 1 year in conjunction with standard care improves ejection fraction and reduces left atrial and ventricular diameters when compared with placebo and standard care (100351). The results of this study are limited by the small sample size, unclear etiology of dilated cardiomyopathy, and potential bias. Another small clinical study in children under 5 years of age with dilated cardiomyopathy and low serum levels of L-carnitine shows that taking L-carnitine 100 mg/kg daily for 3 months improves left ventricular ejection fraction (LVEF), cardiac output, and New York Heart Association (NYHA) classification when compared with baseline (59196). Further research is needed to clarify whether L-carnitine is beneficial for most children with dilated cardiomyopathy, or only those with carnitine deficiency. L-carnitine has also been evaluated in older adults. A meta-analysis of clinical studies in mostly older adults with dilated cardiomyopathy shows that addition of intravenous L-carnitine, alone or followed by oral L-carnitine, 1-6 grams daily to conventional therapy for a total of 10-28 days is associated with a 28% increased likelihood of overall efficacy, with improvements observed in both LVEF and cardiac output, when compared with conventional therapy alone (107405). The validity of these findings is limited by the heterogeneity of the included studies, potential publication bias, and unclear reporting. A small individual clinical study in older adults with ischemic cardiomyopathy shows that taking oral L-carnitine daily for 2 months improves LVEF when compared with baseline (58150). The validity of this finding is limited by the lack of a comparator group.
Dry eye. Topical L-carnitine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Evidence suggests that chronic use of eye drops containing benzalkonium chloride can cause tear film instability and lead to dry eye (90921). One small clinical trial in patients with glaucoma using eye drops containing benzalkonium chloride shows that using additional eye drops containing L-carnitine (1.017%), eledoisin (0.04%), taurine (0.49%), sodium hyaluronate (0.20 grams/100 mL), and vitamin E acetate (0.20 grams/100 mL) (Carnidrop Plus, Sigma-Tau) three times daily for 15 days reduces dry eye symptoms by approximately 50% when compared to baseline (90625). It is unclear if these findings are due to L-carnitine, other ingredients, or the combination.
Endometriosis. Although there has been interest in using oral L-carnitine for endometriosis, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose.
Exercise-induced muscle damage. It is unclear if oral L-carnitine tartrate is beneficial for exercise recovery. Details: A small clinical study in healthy males and females participating in moderate physical activity at least 3 days weekly shows that taking a specific product (Carnipure, Lonza Consumer Health, Inc.) providing elemental L-carnitine 2 grams daily for 5 weeks improves perceived recovery and soreness as well as serum creatine kinase levels by 33% and 28%, respectively, when compared with placebo (107398).
Exercise-induced muscle soreness. Small clinical studies suggest that oral L-carnitine may slightly reduce exercise-induced muscle soreness. Details: Evidence from mostly small clinical trials, when considered alone or combined via meta-analysis, shows that taking L-carnitine 1-3 grams daily for around 3 weeks modestly reduces exercise-induced muscle soreness, especially in the period of 24-48 hours after exercise. Benefits may last up to 96 hours post-exercise. Levels of creatinine kinase, lactate dehydrogenase, and myoglobin also appear to improve with L-carnitine supplementation, reflecting a reduction in muscle damage (58326,58709,59148,101567).
Hepatic encephalopathy. Oral or intravenous L-carnitine may improve biochemical markers of disease severity in patients with hepatic encephalopathy, but L-carnitine does not seem to improve clinically important outcomes such as fatigue, quality of life, or overall disease severity. Details: A meta-analysis of nine studies in adults with hepatic encephalopathy shows that taking L-carnitine 1-6 grams daily orally or intravenously for up to 90 days increases albumin levels and decreases plasma levels of ammonia, bilirubin, aspartate aminotransferase (AST), blood urea nitrogen (BUN), and creatinine, but does not improve fatigue or quality of life, when compared with placebo (102122). A more recent clinical trial shows that taking L-carnitine 2 grams daily for 24 weeks modestly improves bilirubin levels and some measures of cognitive and liver health, but not quality of life, when compared with taking placebo (111876). Two of the clinical trials included in this analysis also show that taking L-carnitine 2 grams daily for 60-90 days significantly improves cognitive function when compared with placebo in adults with hepatic encephalopathy (58174,58204). Another small clinical trial in patients with advanced liver cirrhosis shows that L-carnitine improves psychometric response to the ammonia tolerance test, suggesting that L-carnitine might be useful in the prevention of hepatic encephalopathy (58872). L-carnitine has also been evaluated in combination with rifaximin. A small clinical study in patients with overt hepatic encephalopathy shows that taking oral L-carnitine 1500 mg in combination with rifaximin 1200 mg three times daily for 12 weeks has no effect on the modified portal systemic encephalopathy index when compared with rifaximin alone. L-carnitine improved blood ammonia levels at 4 weeks, but not at 8 or 12 weeks (107410).
Hepatitis-related fatigue. It is unclear if oral L-carnitine is beneficial in patients with hepatitis-related fatigue. Details: One small clinical trial in patients with hepatitis C who are receiving interferon-alpha treatment shows that taking L-carnitine 2 grams daily significantly reduces fatigue when compared with interferon-alpha alone. L-carnitine appears to reduce fatigue within the first 3 months of treatment, but not after 6 months (16104).
Hepatitis B. Oral L-carnitine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with hepatitis B shows that taking a specific vitamin complex providing L-carnitine 2472 mg (Godex, Celltrion Pharm) in combination with entecavir 0.5 grams daily for 12 months normalizes alanine transaminase (ALT) levels in 95% and 100% of patients after 3 months and 12 months, respectively, compared to 59% and 86% of patients taking entecavir alone. However, the L-carnitine complex does not appear to improve aspartate transaminase (AST) levels or reduce hepatitis B virus titers (91724). It is unclear if these findings are due to L-carnitine, other ingredients, or the combination.
Hepatitis C. Small clinical studies suggest that oral L-carnitine may improve response to treatment and markers of liver function in patients with hepatitis C. Details: Two small clinical trials in patients with chronic hepatitis C show that taking L-carnitine 2 grams once or twice daily along with interferon-alpha and ribavirin for 12 months modestly improves response to treatment, increases hemoglobin and red blood cell counts, reduces aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, and reduces steatosis when compared with interferon-alpha and ribavirin treatment alone (58405,59010).
HIV/AIDS. Although there has been interest in using intravenous L-carnitine to increase CD4 counts in patients with HIV/AIDS, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose.
Hyperthyroidism. It is unclear if oral L-carnitine is beneficial in patients with hyperthyroidism. Details: One small clinical trial in females with hyperthyroidism shows that taking L-carnitine 2-4 grams daily for 2-6 months seems to significantly improve symptoms associated with hyperthyroidism, such as palpitations, nervousness, tremors, and asthenia, when compared with placebo (8047).
Hypertriglyceridemia. It is unclear if oral L-carnitine is beneficial in patients with hypertriglyceridemia. Details: Small clinical studies in patients with hypertriglyceridemia show that taking L-carnitine 1 gram daily for 12 weeks does not reduce triglyceride levels when compared with placebo (59028,59244).
Hypothyroidism. It is unclear if oral L-carnitine is beneficial for improving fatigue in patients with hypothyroidism. Details: One small clinical trial in patients with secondary hypothyroidism shows that taking L-carnitine (Ildong Pharmaceutical Co.) 990 mg twice daily for 12 weeks in addition to adequate doses of levothyroxine does not reduce overall fatigue severity when compared with placebo. However, taking L-carnitine might improve physical and mental fatigue in patients with secondary hypothyroidism that are less than 50 years of age. L-carnitine might also improve mental fatigue in patients that underwent thyroidectomy for thyroid cancer (95069).
Infertility. It is unclear if oral L-carnitine is beneficial for female infertility. Details: One uncontrolled clinical trial in females who had failed to conceive in previous in vitro fertilization (IVF) cycles shows that taking L-carnitine (L-CAR Basic Premium; AA Project Co. ltd.) 1000 mg daily for an average of 82 days does not improve the number of retrieved oocytes or fertilization rates when compared with previous IVF cycles. However, embryo quality at days 3 and 5 of insemination was improved, resulting in an increase in the rate of transferable embryos from 60% in previous cycles to 67%, morphologically good-quality embryos from around 46% to 54%, and blastocysts from around 11% to 21%. The most evidence of benefit was seen in those taking L-carnitine for the shortest time length of 7-44 days (96933).
Intermittent claudication. Although there has been interest in using oral L-carnitine for intermittent claudication, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose.
Liver disease. Small clinical studies suggest that oral L-carnitine may modestly improve some, but not all, lipid parameters in adults with liver disease. Details: A meta-analysis of six small, low-quality clinical trials in patients with hepatitis C, nonalcoholic steatohepatitis (NASH), and nonalcoholic fatty liver disease (NAFLD) shows that taking L-carnitine moderately reduces total cholesterol and slightly reduces triglyceride levels, but does not improve low-density lipoprotein (LDL) cholesterol or high-density lipoprotein (HDL) cholesterol levels, when compared with control. Studies evaluating L-carnitine doses of 2 grams daily or less and study durations of 24 months or longer showed the largest effect on lipid levels (104178). Another meta-analysis of preliminary clinical research in patients with hepatitis B or C, hepatic encephalopathy, NASH, or NAFLD shows that taking L-carnitine modestly reduces levels if aspartate aminotransferase (AST) and alanine aminotransferase (AST) when compared with taking placebo or no L-carnitine. Some of the studies included in this analysis used acetyl-L-carnitine. However, a meta-analysis of two studies investigating the effect of carnitine orotate shows that taking this compound increases the proportion of patients with normal ALT levels by 4.6 fold (111871).
Liver transplant. It is unclear if oral L-carnitine is beneficial in patients awaiting a liver transplant. Details: One small clinical trial shows that taking L-carnitine 500 mg three times daily while awaiting a liver transplant does not reduce the incidence of primary graft dysfunction (PGD) or non-function (PNF) when compared with placebo. However, survival one month after surgery was 97% in those taking L-carnitine, compared with 74% in those taking placebo (101562). This study may have been inadequately powered to detect a difference in the incidences of PGD and PNF between groups.
Low birth weight. It is unclear if oral or intravenous L-carnitine is effective for increasing body weight in preterm infants. Several small clinical studies show conflicting results. Details: Several very small clinical trials in preterm infants receiving total parenteral nutrition show that administering L-carnitine orally at a dose of 13-60 mcmol/kg or intravenously at a dose of 10 mg/kg or 50-100 mcmol/kg daily can improve fat utilization and weight gain when compared with control (3633,3634,3635,3636,3637,58902,59097). However, other small clinical studies show that supplementation with L-carnitine does not significantly increase body weight in preterm infants (58190,58800,59161). The reasons for the discrepant findings are unclear, but due to small study size, some of the studies may have been underpowered to detect significant differences between groups.
Lyme disease. Although there has been interest in using oral L-carnitine for Lyme disease, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose.
Metabolic syndrome. It is unclear if oral or intravenous L-carnitine is beneficial in patients with metabolic syndrome. Details: One very small clinical trial in patients with metabolic syndrome undergoing 2 days of moderate calorie restriction followed by a 5-day modified fasting period shows that intravenous L-carnitine 2 grams twice daily for 7 days increases weight loss by 1.4 kg and decreases waist circumference by 3.3 cm when compared with intravenous saline. Perceived hunger scores, physical fatigue, and insulin levels were also improved. However, there were no effects on blood pressure (90634). Other clinical research in patients with metabolic syndrome and a total carotid plaque volume of at least 50 mm³ shows that taking L-carnitine 2 grams daily for 6 months does not affect the progression of carotid plaque volume when compared with taking placebo. Also, taking L-carnitine increased the progression of carotid plaque stenosis by 9.3%, as well as levels of low-density lipoprotein (LDL) cholesterol, in this population (111879).
Migraine headache. It is unclear if oral L-carnitine is beneficial in patients with migraine headaches. Details: One small clinical trial in patients with migraines shows that taking L-carnitine 500 mg daily, with or without magnesium oxide, for 12 weeks does not significantly reduce migraine frequency or severity when compared with a control (59030). However, another small preliminary clinical trial in children with episodic migraines shows that taking L-carnitine 25 mg per kg twice daily for 12 weeks prophylactically is as effective as taking propranolol 1 mg/kg once daily for reducing the frequency, severity, and duration of migraine headaches (111870). These studies were small and may have been underpowered to detect differences between groups.
Muscle cramps. It is unclear if oral L-carnitine is beneficial in patients with muscle cramps. Details: One small, uncontrolled clinical trial in adults with type 2 diabetes shows that taking L-carnitine 300 mg twice daily for 4 months decreases the monthly frequency of muscle cramps from around 4 cramps per month at baseline to around 1 cramp per month after treatment. When compared with baseline, pain was also reduced by about 1 point on a 5-point scale (96922). However, the lack of a placebo control group limits the validity of these findings.
Multiple sclerosis-related fatigue. It is unclear if oral L-carnitine is beneficial in patients with multiple sclerosis-related fatigue. Details: Some patients with multiple sclerosis have low blood levels of L-carnitine. Additionally, immunosuppressive therapy for multiple sclerosis can cause fatigue. One small, open-label clinical trial in patients with multiple sclerosis receiving immunosuppressive therapy and with low L-carnitine levels shows that taking L-carnitine 3-6 grams daily decreases some measures of fatigue when compared with no treatment (16107).
Myocardial infarction (MI). It is unclear if oral or intravenous L-carnitine is beneficial in patients who have experienced an MI. Details: Some clinical research shows that taking L-carnitine orally or intravenously after MI reduces premature ventricular beats (58172,59044), improves myocardial viability (59248) and left ventricular function (3628), and reduces mortality (3627,3629,59037). However, other studies show no change in left ventricular functioning (58148) or mortality after taking L-carnitine (3628,58225,90630). The reasons for these discrepant findings are unclear, but may be due to differences in the dosing regimens and length of follow-up. Oral L-carnitine doses have ranged from 2-4 grams daily for up to 12 months (3627,3629,59248). Intravenous L-carnitine has been dosed at 5 grams within the first 36 hours after an MI followed by 3 grams twice daily on days 3-7 (58172), 100 mg/kg every 12 hours for 36 hours (59044), or 9 grams daily for 5 days followed by oral L-carnitine 6 grams daily for 12 months (3628).
Narcolepsy. It is unclear if oral L-carnitine is beneficial in patients with narcolepsy. Details: One small clinical trial in patients with narcolepsy shows that taking L-carnitine 340 mg in the morning and 170 mg in the evening for 8 weeks reduces dozing off time during the day by about 9 minutes when compared with placebo. However, the number of naps needed, quality of life, and sleepiness are not affected (90624).
Neonatal apnea. It is unclear if intravenous L-carnitine is beneficial for preventing neonatal apnea in premature infants. Details: One small clinical trial in premature infants shows that adding L-carnitine 30 mg/kg daily to total parenteral nutrition or oral feeds does not affect ventilator requirements or reduce the incidence of apnea when compared with placebo (58163).
Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral L-carnitine is beneficial in children and adults with NAFLD. Details: One small clinical study in adults with NAFLD shows that taking L-carnitine 600 mg daily for 3 months improves markers of liver function when compared with baseline. No improvements in liver function markers were reported in patients in the control group; however, no statistical comparisons were conducted between groups (58808). A small clinical study in children aged 5-15 years with NAFLD receiving vitamin E shows that taking L-carnitine 25 mg/kg twice daily (maximum of 500 mg twice daily) for 3 months has no effect on aminotransferase concentrations or sonographic grades of fatty liver when compared with placebo (107401).
Nonalcoholic steatohepatitis (NASH). It is unclear if oral L-carnitine is beneficial in patients with NASH. Details: One small clinical trial in patients with NASH shows that taking L-carnitine 1 gram after breakfast and 1 gram after dinner daily along with following a specific diet improves markers of liver function when compared with diet alone (58715). Another small clinical trial in patients with obesity and nonalcoholic steatohepatitis taking simvastatin 20 mg daily and following a hypocaloric diet shows that taking L-carnitine 10 mL twice daily for 90 days modestly reduces BMI, and improves liver health, lipid, and glycemic indices, when compared with taking a product described as essential phospholipids (111893).
Obesity. Oral L-carnitine seems to have a small effect on weight loss in overweight or obese individuals when taken for up to 6 months, but some conflicting results exist. Doses of 2 grams daily seem to offer the most benefit. Details: Meta-analyses of clinical trials show that taking L-carnitine 250 mg to 4 grams daily reduces weight and body mass index (BMI) by a small amount when compared with a control group not taking L-carnitine (95074,101563,101564). Subgroup analyses show that L-carnitine only reduces BMI and weight in overweight or obese patients. Taking L-carnitine did not affect weight or BMI in patients with a BMI of up to 25 kg/m2 or in patients undergoing hemodialysis (101563,101564). Another subgroup analysis shows that the largest benefit occurs at a dose of 2 grams daily (101564). In patients with obesity and nonalcoholic steatohepatitis taking simvastatin 20 mg daily and following a hypocaloric diet, one clinical trial shows that taking L-carnitine 10 mL twice daily for 90 days modestly reduces BMI, and improves liver health, lipid, and glycemic indices, when compared with taking a product described as essential phospholipids (111893). However, conflicting results exist. One subgroup analysis in overweight or obese individuals shows that there is no effect on BMI when L-carnitine is taken for 24 weeks or more (101563). One meta-analysis of two small clinical trials in patients with overweight or obesity shows that taking L-carnitine is no more effective than lifestyle modification for reducing body weight (111866). Also, some clinical research shows that taking L-carnitine does not reduce body weight in obese females. Doses used in these studies include L-carnitine 1 gram daily for 12 weeks or 2 grams twice daily for 8 weeks along with exercise (58151,111872). The effect of L-carnitine on cardiovascular risk has also been examined in patients with obesity. One small clinical trial shows that taking L-carnitine 1 gram daily for 12 weeks modestly reduces the lipid accumulation index, based on waist circumference and blood triglyceride levels, when compared with taking placebo. However, there was no effect on other cardiovascular risk indices based on ratios of triglycerides, high-density lipoprotein (HDL) cholesterol, and/or low-density lipoprotein (LDL) cholesterol levels (111872). L-carnitine has also been evaluated in combination with weight loss medications. Clinical research shows that taking L-carnitine 2 grams daily along with orlistat 360 mg daily or sibutramine 10 mg daily for 1 year decreases body weight and BMI when compared with orlistat or sibutramine alone in obese adults with type 2 diabetes (58778,58830,58882).
Osteoarthritis. It is unclear if oral L-carnitine is beneficial in patients with knee osteoarthritis. Details: A small clinical study in females with knee osteoarthritis and overweight or obesity who are on a low-calorie diet shows that taking L-carnitine 1 gram daily for 12 weeks does not improve pain, stiffness, or physical function when compared with placebo (107403).
Pemphigus. Although there has been interest in using oral L-carnitine for glucocorticoid-induced muscle wasting in patients with pemphigus, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose.
Peripheral arterial disease (PAD). It is unclear if oral L-carnitine is beneficial in patients with PAD. Details: One small clinical trial in patients with PAD shows that taking L-carnitine 2 grams twice daily for 3 weeks may improve walking distances in people with PAD (3631). However, another small clinical trial in patients with PAD or coronary heart disease shows that taking L-carnitine 2 grams two hours before exercise does not improve endurance (58196). Also, adding L-carnitine 1 gram twice daily to cilostazol therapy for 180 days does not appear to confer additional benefit in this patient population (59023).
Polycystic ovary syndrome (PCOS). It is unclear if oral L-carnitine is beneficial for improving pregnancy rates or cardiovascular risk in people with PCOS. The effect of L-carnitine on body composition has promising results. Details: Clinical research shows that adding L-carnitine 3 grams daily for 3 months to standard clomiphene plus metformin therapy improves menstrual regularity by 20%, ovulation rate by 24%, and pregnancy rate by 21% when compared with placebo (102123). Preliminary clinical research in patients with PCOS who are resistant to both clomiphene and human chorionic gonadotropin (HCG) shows that taking L-carnitine 2 grams twice daily from day 3 of clomiphene treatment until HCG injection results in the presence of a dominant follicle in 64% of cycles and pregnancy in 20% of cycles (96936). However, L-carnitine may not be beneficial in combination with assisted reproductive technology (ART), including in vitro fertilization and intracytoplasmic sperm injection. A small clinical study in patients with PCOS receiving ART in combination with a gonadotropin-releasing hormone antagonist protocol shows that adding L-carnitine 3000 mg daily during the induction of ovulation (from the second day of the cycle until the day of oocyte triggering) does not improve pregnancy rates in frozen-thawed embryo transfer cycles when compared with control (107409). The effect of L-carnitine has also been examined on anthropometric and cardiovascular risk indices in patients with PCOS. One small clinical study shows that taking L-carnitine 250 mg daily for 12 weeks reduces body weight by 2.8 kg, body mass index (BMI) by 1.2 kg/m2, waist circumference by 1.7 cm, and hip circumference by 2.2 cm when compared with placebo (96935). A meta-analysis of this and other small studies also shows that L-carnitine modestly reduces BMI when compared with placebo in patients with PCOS (111873). Although several studies also show improvements in markers of glycemic control and insulin sensitivity, most research does not support beneficial effects on lipid levels, cardiovascular risk, or liver fat content (96935,107402,107404).
Rett syndrome. It is unclear if oral L-carnitine is beneficial in patients with Rett syndrome. Details: Two small clinical studies in children with Rett syndrome show that taking L-carnitine 100 mg/kg daily in two or three divided doses for up to 6 months modestly improves well-being, motor skills, sleep efficiency, and communication skills when compared with control or placebo (1433,58161).
Sarcopenia. Oral L-carnitine may be beneficial for preventing sarcopenia in adults over 75 years of age, but not in healthy older females. Details: One small clinical trial in healthy, active, older females aged 65-70 years shows that taking L-carnitine, as L-carnitine-l-tartrate 1500 mg, daily for 24 weeks does not improve muscle strength or muscle mass when compared with placebo (96930). An additional preliminary clinical trial in females aged 60-75 years taking part in a twice weekly resistance exercise program shows that taking L-carnitine tartrate 1 gram daily with L-leucine 3 grams daily for 24 weeks does not improve muscle strength or volume when compared with taking L-leucine 4 grams daily or no supplementation (111880). These studies were small and may have been underpowered to detect differences. In contrast, in weaker adults 75 years of age and older, taking L-carnitine 2-4 grams daily for 1-6 months increases muscle mass by approximately 2-4 kg when compared with placebo (16109,16111).
Sepsis. Small clinical studies suggest that intravenous L-carnitine may not reduce mortality in patients with sepsis, although patients with more severe sepsis may see some benefit. Details: Meta-analyses of generally low-quality small clinical trials in patients with sepsis shows that intravenous administration of L-carnitine, 2-6 grams as a bolus followed by a 4-12 gram infusion, does not reduce the risk of 28-day or 1-year mortality when compared with placebo (104180,111868). However, in a subgroup analysis of patients with more severe sepsis, classified as those with a sequential organ failure assessment score (SOFA) of greater than 12, the risk of 1-year mortality was reduced by 32% when compared with placebo (104180).
Spinal muscular atrophy. Although there has been interest in using oral L-carnitine for spinal muscular atrophy, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose.
Theophylline-induced cardiac toxicity. It is unclear if intravenous L-carnitine is beneficial in patients with theophylline-induced cardiac toxicity. Details: One small clinical trial shows that intravenous administration of L-carnitine 100 mg/kg over 30-60 minutes followed by 50 mg/kg every 8 hours along with intravenous propranolol within 24 hours of theophylline intoxication improves symptoms associated with theophylline-induced cardiac toxicity when given along with standard treatment. This combination led to greater improvements than either agent used alone. These included improvements in serum theophylline levels, heart rate, arrhythmia, mean arterial pressure, and duration of hospital stay. When L-carnitine was used without propranolol, only respiratory rate and theophylline levels over 24 hours were improved to a greater extent than with standard treatment alone (101566).
Toxin-induced liver damage. Small clinical studies have evaluated oral and intravenous L-carnitine for the management of liver damage caused by different classes of drugs, including antimycobacterial antibiotics and asparaginase-based agents, with promising results. Details: The antimycobacterial antibiotics used to treat tuberculosis, including isoniazid, rifampicin, and pyrazinamide, have been associated with hepatotoxicity (90922). Clinical research shows that taking L-carnitine 2 grams in two divided doses daily for 4 weeks along with a standard treatment regimen for tuberculosis reduces the percentage of treatment-naïve patients with drug-induced hepatotoxicity by almost half when compared with placebo (26499). The asparaginase-based medications have also been associated with hepatotoxicity. Two case series of children with hyperbilirubinemia caused by treatment with L-asparaginase or pegaspargase show that administering intravenous L-carnitine 50-100 mg/kg daily improves bilirubin levels (100353,100354). One case series also suggests that taking oral L-carnitine 50-100 mg/kg daily can help to prevent hyperbilirubinemia in patients with a history of asparaginase-induced hepatotoxicity (100353).
Traumatic brain injury (TBI). Although there has been interest in using oral L-carnitine for TBI, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose.
Urinary tract infections (UTIs). It is unclear if oral L-carnitine is beneficial in children with UTIs. Details: One small clinical trial in children 6 months to 10 years of age shows that taking L-carnitine 50 mg/kg daily as a syrup along with antibiotics for 7 days prevents renal scarring associated with acute pyelonephritis. Kidney damage was resolved in 50% of children taking L-carnitine, compared with 13% of children taking placebo. There were no differences in urine cultures between groups (101568).
Venous leg ulcers. Although there has been interest in using oral L-carnitine for venous leg ulcers, there is insufficient reliable information about the clinical effects of L-carnitine for this purpose. More evidence is needed to rate L-carnitine for these uses.

L-TRYPTOPHAN

Depression. Although it is unclear if oral L-tryptophan is beneficial in patients with depression, there is a lack of supporting evidence and a rare risk of adverse effects such as serotonin syndrome. Details: Guidelines from The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce state that L-tryptophan is not currently recommended for adjunctive or monotherapy use for major depressive disorder. The available small and low-quality studies have not supported L-tryptophan for this use (110318). Some older research suggests that taking L-tryptophan with clomipramine might improve the effectiveness of clomipramine (10856). However, it is not clear whether L-tryptophan is beneficial when taken along with newer classes of antidepressants. Also, the CANMAT Taskforce cautions the co-use of L-tryptophan with serotonergic antidepressants due to the rare risk of serotonin syndrome (110318).

Anxiety. Although there is interest in using oral L-tryptophan for anxiety, there is insufficient reliable information available about the clinical effects of L-tryptophan for this condition.
Athletic performance. It is unclear if oral L-tryptophan is beneficial for improving athletic performance. Details: Some clinical research shows that taking L-tryptophan 300 mg orally along with a sugar and electrolyte drink twice daily for 3 days prior to exercise and on the day of exercise improves power output during the last 20 minutes of exercise when compared with taking a sugar and electrolyte drink without L-tryptophan. The improvement in power output increases distance covered by about 5% without increasing perceived exhaustion (91462). However, other clinical research shows that taking L-tryptophan 12 mg/kg after 5 minutes of warm-up and then 6 mg/kg orally every 15 minutes during exercise does not improve time to exhaustion in endurance-trained male athletes (1135). Reasons for the discrepancy are not clear. It is possible that L-tryptophan benefits some measures of athletic performance, but not others.
Bruxism. It is unclear if oral L-tryptophan is beneficial for bruxism. Details: A very small clinical trial in adults with nocturnal bruxism shows that taking L-tryptophan 50 mg/kg daily orally for 8 days does not improve levels of teeth grinding when compared with placebo (1139).
Cognitive impairment. It is unclear if oral L-tryptophan is beneficial in patients with cognitive impairment. Details: Clinical research in elderly individuals with mild cognitive impairment shows that taking L-tryptophan 95 mg orally with docosahexaenoic acid (DHA) 720 mg, eicosapentaenoic acid (EPA) 286 mg, vitamin E 16 mg, soy phospholipids 160 mg, and melatonin 5 mg (IBSA Farmaceutici Italia) nightly for 12 weeks improves cognitive function and sensitivity to smells by a small amount when compared with placebo. Patients treated with the combination showed a 1-point improvement in cognitive function based on the mini-mental state examination (MMSE) scale, while patients in the placebo group showed a 2-point decline (62847). However, these results might not be clinically significant. Also, it is not known if any potential benefit is due to L-tryptophan, other ingredients, or the combination.
Fibromyalgia. It is unclear if oral L-tryptophan is beneficial in patients with fibromyalgia. Details: Preliminary clinical research in females with fibromyalgia shows that eating a standardized Mediterranean diet supplemented with walnuts, to supply L-tryptophan 60 mg daily and magnesium 60 mg daily for 16 weeks, modestly reduces anxiety, mood disturbance, eating disorders, and dissatisfaction with body image, but does not affect sleep, when compared with the Mediterranean diet alone. It is unclear if these effects are due to L-tryptophan, magnesium, other components of the added foods, or the combination (103172).
Gout. Oral L-tryptophan has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with mild hyperuricemia shows that taking a powder containing L-tryptophan 0.2 grams and glycine 3 grams nightly for 6 weeks decreases serum uric acid levels by 0.3 mg/dL when compared with placebo. Improvements also occurred in the subgroup of patients with uric acid levels greater than 7 mg/dL, the point at which symptoms of gout can occur (99883). However, the effect of this combination for gout-related pain is unknown. Also, it is not clear if this effect is due to L-tryptophan, glycine, or the combination.
Helicobacter pylori. A small clinical study suggests that adding L-tryptophan to treatment with omeprazole increases ulcer healing. Details: Clinical research shows that taking L-tryptophan (Ardeydorm, Ardeypharm GmbH) 250 mg twice daily in combination with omeprazole 20 mg twice daily for 21 days improves ulcer healing rates when compared with omeprazole alone in individuals with H. pylori-associated gastroduodenal ulcers (62803).
Insomnia. Small clinical studies suggest that oral or intravenous L-tryptophan may modestly improve symptoms, particularly sleep latency, in patients with insomnia. Details: Clinical research shows that taking L-tryptophan 500 mg twice daily for 2 weeks improves insomnia in patients undergoing detoxification from methamphetamine or ketamine when compared with placebo. However, it does not seem to improve psychological symptoms in these patients (97242). One small clinical study shows that taking L-tryptophan orally, 1 gram 20 minutes before bed, might decrease sleep latency and improve mood when compared with placebo in healthy people with insomnia. Smaller doses of 250 mg and 500 mg did not demonstrate benefit (1146). Other clinical research shows that a single 5 gram intravenous infusion of L-tryptophan decreases sleep latency and increases total sleep time when compared with baseline in patients with insomnia (14896).
Migraine headache. The incidence of migraine headaches may decrease with increased dietary L-tryptophan intake. Details: Preliminary clinical research shows that a dietary L-tryptophan intake of 0.84-1.06 grams per day reduces the odds of experiencing a migraine of any type by 54% to 60% when compared with an intake of 0.56 grams per day or less (103171).
Myofascial pain syndrome. It is unclear if oral L-tryptophan is beneficial in patients with myofascial pain syndrome. Details: Some clinical research in adults with chronic maxillofacial pain shows that taking L-tryptophan orally 3 grams daily for 4 weeks is associated with a greater reduction in pain score and an increase in pain tolerance when compared with placebo (1145). However, other clinical research shows that L-tryptophan does not reduce pain when compared with placebo (1140).
Obesity. Although there is interest in using oral L-tryptophan for obesity, there is insufficient reliable information available about the clinical effects of L-tryptophan for this condition.
Premenstrual dysphoric disorder (PMDD). Limited clinical research suggests that L-tryptophan may reduce symptoms of PMDD. Details: A small clinical study in adults with PMDD shows that taking L-tryptophan orally 6 grams daily for approximately 17 days, from the time of ovulation to the third day of menstruation, for three consecutive cycles reduces mood swings, tension, and irritability when compared with placebo (6246).
Premenstrual syndrome (PMS). Although there is interest in using oral L-tryptophan for premenstrual syndrome, there is insufficient reliable information available about the clinical effects of L-tryptophan for this condition.
Seasonal affective disorder (SAD). It is unclear if oral L-tryptophan is beneficial in patients with SAD. Details: One very small clinical crossover study shows that taking L-tryptophan 4-6 grams orally daily in divided doses for 4 weeks improves seasonal affective disorder to a similar degree as receiving light therapy for 2 weeks (6247). However, this study was not powered to detect a difference between groups.
Sleep apnea. Although there is interest in using oral L-tryptophan for sleep apnea, there is insufficient reliable information available about the clinical effects of L-tryptophan for this condition.
Smoking cessation. It is unclear if oral L-tryptophan is beneficial for smoking cessation. Details: A small clinical study in adults attempting to quit smoking shows that taking L-tryptophan 50 mg/kg daily orally for 2 weeks in conjunction with standard smoking cessation treatments results in fewer daily cigarettes smoked when compared with placebo. Reported anxiety and other withdrawal symptoms were also lower in the L-tryptophan group (1138). However, the study was not powered to detect a statistically significant difference in these outcomes between groups.
Tourette syndrome. Although there is interest in using oral L-tryptophan for Tourette syndrome, there is insufficient reliable information available about the clinical effects of L-tryptophan for this condition. More evidence is needed to rate L-tryptophan for these uses.

Herpes labialis (cold sores). Most clinical research shows that oral lysine can prevent and treat herpes labialis. The benefits of topical lysine are unclear. Details: Despite one small clinical study that found no benefit (1116), most clinical research shows that taking oral lysine monohydrochloride 1000-1248 mg daily or 1000 mg three times daily reduces the recurrence of herpes labialis infections when compared with placebo (1114,1115,1118,1120,19390,19391). Also, small clinical studies show that taking oral lysine 1000 mg daily in up to two divided doses for up to 12 months or 1000 mg three times daily for 6 months reduces the severity and healing time of herpes labialis infections when compared with placebo (1119,1120). Topical lysine has also been studied in combination with other ingredients. A small, open-label study shows that applying a specific combination product containing lysine and zinc oxide plus 14 other ingredients (Super Lysine Plus +) topically every 2 hours for 11 days seems to decrease symptoms and duration of herpes lesions when compared with baseline (11051). The validity of this finding is limited by the lack of a comparator group. Also, it is unclear if any benefit is due to lysine, other ingredients, or the combination.

Athletic performance. Although there is interest in using oral lysine for improving athletic performance, there is insufficient reliable information about the clinical effects of lysine for this purpose.
Canker sores. It is unclear if oral lysine is beneficial in patients with canker sores. Details: Preliminary clinical research shows that taking oral lysine 500 mg daily may be beneficial for preventing canker sores, and taking oral lysine 4000 mg daily may be beneficial for decreasing the duration of canker sores (19390).
Child growth. Oral lysine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in children aged 4-9 years old with idiopathic short stature shows that taking a combination oral solution containing lysine, inositol, and vitamin B12 10 mL twice daily along with moderate stretching exercises for 12 months increases height, growth velocity, and serum growth indicators and reduces height standard deviation scores when compared with control. However, the combination product does not impact body mass index or the ratio of bone age to chronological age when compared with control (112280). It is unclear if these findings are due to lysine, other ingredients, or the combination.
Diabetes. It is unclear if oral lysine is beneficial in patients with diabetes. Details: One small clinical study shows that taking lysine hydrochloride 500 mg twice daily for 2 months does not affect fasting or postprandial blood glucose levels or glycated hemoglobin in patients with type 2 diabetes when compared a calcium phosphate control (19395).
Diabetic foot ulcers. It is unclear if topical lysine is beneficial in patients with diabetic foot ulcers. Details: A small clinical study in adults with type 2 diabetes and grade 2 diabetic foot ulcers shows that applying topical lysine 15% cream twice daily with standard treatment for 8 weeks improves the rate of wound healing and skin color surrounding the wound, and also reduces ulcer size, depth, margins, undermining, edema, induration, granulation tissue, necrotic tissue amount and type, exudate type and amount, and epithelialization when compared with control (112279). The validity of the findings is limited by a lack of blinding and small sample size.
Hypertension. Limited clinical research shows that oral lysine can reduce blood pressure in hypertensive patients who have deficient dietary lysine intake. Details: Preliminary clinical research in malnourished people in West Africa with deficient lysine intake shows that taking lysine orally 500 mg twice daily for 16 weeks reduces systolic blood pressure (SBP) when compared with placebo in those with hypertension at baseline. The mean SBP was reduced by 17 mmHg in males and 12 mmHg in females. Lysine supplementation did not affect SBP in people who were normotensive at baseline (104104).
Hypertriglyceridemia. It is unclear if oral lysine is beneficial for patients with hypertriglyceridemia. Details: Preliminary clinical research shows that taking lysine 1 gram daily for 12 weeks, with or without vitamin B6 50 mg daily, does not affect body weight, triglyceride levels, or blood glucose levels when compared with placebo in males with hypertriglyceridemia. Furthermore, this dose of lysine, taken alone or in combination with vitamin B6, appears to slightly decrease high-density lipoprotein (HDL) cholesterol levels after 12 weeks when compared with placebo (90642).
Muscle strength. Higher dietary intake of lysine seems to improve muscle strength in young under- or well-nourished males. Details: Preliminary clinical research in young, under- or well-nourished males shows that consuming lysine 80 mg/kg daily in the diet for 8 weeks improves muscle strength of the forearm by approximately 7.5% when compared with a diet containing lysine 25-40 mg/kg daily (90643).
Pressure ulcers. A small study suggests that topical lysine may be beneficial for pressure ulcers. Details: A small clinical study in hospitalized adults shows that applying a specific cream containing lysine hyaluronate (Lys-HA, Lysial, Fatai-Nyl Srl; Jasper LLC) topically with dressing changes once daily for one week, then once every 2 days for one week, reduces pressure ulcer size when compared with a cream containing sodium hyaluronate. The effect appears to be greater in patients with more advanced (stage 3) ulcers compared to less advanced (stage 1) ulcers (90641).
Schizophrenia. Large doses of oral lysine seem to improve schizophrenia symptoms in patients taking antipsychotic medications. Details: Clinical research in people with schizophrenia not controlled by risperidone shows that taking L-lysine 2 grams three times daily for 8 weeks improves symptoms by approximately 34% when compared with placebo. Negative and psychopathologic symptoms appear to improve the most (90645). In patients stabilized on antipsychotic medications, preliminary clinical research suggests that taking L-lysine 6 grams once daily for 4 weeks improves positive symptoms of schizophrenia, particularly delusions and suspiciousness/persecution, when compared with baseline. However, this improvement was not significant when compared with placebo (90644).
Stress. Limited clinical research in economically disadvantaged populations shows that fortifying wheat with lysine may reduce stress and anxiety. Details: Preliminary clinical research shows that consuming wheat that has been fortified with lysine 4.2 grams/kg reduces stress in females and reduces anxiety in males in economically disadvantaged populations that typically consume cereal-based diets when compared with control (19394). More evidence is needed to rate lysine for these uses.

Neural tube birth defects. High dietary intake of methionine during pregnancy seems to reduce the risk of neural tube birth defects. Details: Population research has found that higher dietary intake of methionine during pregnancy is associated with a reduced risk of neural tube defects when compared with lower dietary intake (63117,63135).

Acetaminophen poisoning. It is unclear if oral methionine is beneficial in patients with acute acetaminophen poisoning. Details: Observational research has found that taking methionine 2.5 grams every 4 hours for a total of four doses, starting within 10 hours of acetaminophen overdose, may have similar efficacy to acetylcysteine for preventing liver damage and death (2413).
Allergic rhinitis (hay fever). Although there has been interest in using oral methionine for seasonal allergies, there is insufficient reliable information about the clinical effects of methionine for this purpose.
Asthma. Although there has been interest in using oral methionine for asthma, there is insufficient reliable information about the clinical effects of methionine for this purpose.
Breast cancer. It is unclear if high dietary intake of methionine reduces the risk of breast cancer. Details: A meta-analysis of observational studies suggests that higher dietary intake of methionine is associated with a 6% lower risk of breast cancer, especially for postmenopausal adults, when compared with lower intake. Increasing dietary intake of methionine by 1 gram daily may be associated with a 4% reduction in the risk of breast cancer. These results appear to be more prominent in postmenopausal adults when compared with premenopausal adults; however, this could have been by chance due to the small number of studies that assessed premenopausal adults (94093). A more recent meta-analysis, including 4 additional observational studies, suggests that there is no significant association between methionine intake and breast cancer risk. This finding is largely influenced by inclusion of the European Prospective Investigation into Cancer and nutrition (EPIC) cohort study, which analyzed data from over 300,000 subjects and found no relationship between methionine intake and breast cancer risk (111416).
Cisplatin-associated ototoxicity. It is unclear if oral D-methionine prevents cisplatin-associated ototoxicity. Details: A small clinical study in adults with cancer receiving cisplatin shows that taking D-methionine 100 mg/kg one hour prior to chemotherapy for up to 5 cycles prevents shifts in the hearing threshold at all four tested frequencies, compared with shifts occurring at three of the four tested frequencies in those receiving placebo (108039). The validity of these findings is limited by the lack of statistical comparison between groups.
Colorectal cancer. It is unclear if high dietary intake of methionine reduces the risk of colorectal cancer. Details: A meta-analysis of observational research has found that higher dietary intake of methionine is associated with an 11% lower risk of colorectal cancer, a 23% lower risk of colon cancer, and a 12% lower risk of rectal cancer, when compared with lower intake of methionine. Increasing dietary intake of methionine by 1 gram daily is associated with a 11% reduction in the risk of colorectal cancer. Subgroup analyses have shown a significant inverse relationship between risk of colorectal cancer and dietary methionine intake in patients followed for at least 13.3 years, in Western populations, and in males (94094). There is some evidence that high dietary intake of methionine and folate might have a synergistic effect in decreasing the risk of colon cancer, especially in those with a family history of colon cancer and in those who consume large amounts of alcohol (9325,9326).
Genital herpes. Oral L-methionine has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A small clinical study in patients with genital warts caused by herpes simplex virus (HSV) shows that taking acyclovir 200 mg five times daily for 5 days followed by 4 capsules of a combination product providing a total daily dose of L-methionine 200 mg, coenzyme Q10 50 mg, vitamin E 50 mg, and selenium 50 mcg for 90 days increases the rate of skin reepithelization by approximately 2 days and decreases the incidence of relapse when compared with acyclovir alone. Patients receiving combination therapy had a relapse rate of 13%, compared with a rate of 43% with acyclovir alone (94091).
Herpes zoster (shingles). Oral L-methionine has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A small clinical study in patients with herpes zoster shows that taking acyclovir 800 mg five times daily for 10 days followed by 4 capsules of a combination product providing a total daily dose of L-methionine 200 mg, coenzyme Q10 50 mg, vitamin E 50 mg, and selenium 50 mcg for 90 days increases the rate of skin reepithelization by approximately 2 days, decreases the incidence of relapse, and decreases postherpetic neuralgia pain when compared with acyclovir alone. Patients receiving combination therapy had a relapse rate of 7%, compared with a rate of 44% with acyclovir alone (94091).
Human papillomavirus (HPV). It is unclear if oral methionine is beneficial for the treatment of HPV lesions or for reducing the incidence of relapse. Details: A clinical study in patients aged 14 years or older with cutaneous warts caused by HPV shows that receiving conventional therapy in combination with one capsule of a product containing methionine, echinacea, inulin, taurine, vitamin A, vitamin C, coenzyme Q10, vitamin B3, zinc gluconate, and probiotics (Immuno Skin Plus tablets, Morgan Pharma S.r.l) daily for 20 days each month for 4 months reduces the number of warts at 6 months by about 5, with complete remission achieved in 86% of patients. The group receiving conventional therapy alone had a reduction in the number of warts by about 3, with complete remission achieved in 55% of patients. Conventional therapy consisted of either liquid nitrogen cryotherapy or topical therapy with salicylic acid 15% and lactic acid 15%. These findings are limited by the fact that patients in the combination therapy group had more warts at baseline when compared with those receiving conventional therapy alone (94092). Another small clinical study in patients with skin warts caused by HPV shows that cryotherapy followed by taking 4 capsules of a product containing a total dose of L-methionine 200 mg, coenzyme Q10 50 mg, vitamin E 50 mg, and selenium 50 mcg daily for 180 days increases the rate of complete recovery and decreases the incidence of relapse when compared with cryotherapy followed by placebo. At 180 days, 56% of patients in the active group experienced complete recovery, compared with 44% in the placebo group, and 30% of patients in the active group experienced a relapse, compared with 41% in the placebo group (94091). It is unclear if these effects are due to methionine, other ingredients, or the combination.
Menopausal symptoms. It is unclear if oral L-methionine is beneficial for reducing hot flashes. Details: Preliminary clinical research in postmenopausal adults experiencing at least 5 hot flashes daily for the prior two months shows that taking L-methionine 1 gram twice daily for 12 weeks, then 2 grams twice daily for 8 weeks, does not improve hot flashes when compared with placebo (94090).
Pancreatitis. Oral methionine has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A meta-analysis of eight randomized and nonrandomized clinical studies in patients with chronic or recurrent acute pancreatitis shows that taking a combination of methionine, selenium, vitamin E, vitamin C, and beta-carotene reduces pain when compared with placebo. However, when the two nonrandomized studies were excluded, the significant reduction in pain was lost. Daily doses of individual components studied included methionine 1.6-2.88 grams, selenium 300-600 mcg, vitamin E 188-280 mg, vitamin C 540-720 mg, and beta-carotene 12-54 mg. The study durations ranged from 10 weeks to 12 months (94095). The validity of these findings is limited by the heterogeneity of the included studies.
Parkinson disease. Although there has been interest in using oral methionine for Parkinson disease, there is insufficient reliable information about the clinical effects of methionine for this purpose.
Urinary tract infections (UTI). Oral methionine has only been evaluated in combination with other ingredients; its effects when used alone is unclear. Details: A low-quality observational study in patients with symptomatic UTI and culture-confirmed bacteriuria during pregnancy has found that taking a specific combination of methionine 800 mg, Hibiscus sabdariffa extract 200 mg, and Boswellia serrata 200 mg (Acidif Plus, Biohealth S.r.l) daily for one week increases the rate of negative urine cultures to 70% and symptom resolution to 63%, compared with 43% and 46%, respectively, in patients who increased fluid intake but did not take the combination product (97263). The validity of these findings is limited by the fact that the study groups were not comparable at baseline.
Wound healing. Although there has been interest in using oral methionine for wound healing, there is insufficient reliable information about the clinical effects of methionine for this purpose. More evidence is needed to rate methionine for these uses.

Vitiligo. Small clinical studies suggest that oral or topical L-phenylalanine, when used in combination with UVA light, might modestly improve symptoms in adults and children with vitiligo. Details: Taking L-phenylalanine, as 50 mg/kg two to three times weekly or up to 100 mg/kg once daily orally for up to 3 months, or applying L-phenylalanine 10% cream topically, both in combination with UVA light exposure, seem to be effective for treating vitiligo in adults (2461,2463,2464,2466) and in children (2467).

Attention deficit-hyperactivity disorder (ADHD). Taking phenylalanine orally does not seem to be beneficial for ADHD. Details: Some research suggests that patients with ADHD have lower levels of amino acids such as phenylalanine (9948), but neither D-phenylalanine nor DL-phenylalanine appear to have any sustained effect on ADHD symptoms (9950,9951).
Pain (chronic). Taking D-phenylalanine orally does not seem to be beneficial for chronic pain. Details: A small clinical study in patients with chronic pain of various etiologies shows that taking D-phenylalanine 250 mg four times daily for 4 weeks does not reduce pain when compared with placebo (2459). Additionally, a small clinical study in adults with chronic low back pain shows that taking D-phenylalanine 4 grams orally as a single dose prior to acupuncture does not enhance analgesic effects when compared with acupuncture alone (2456).

Aging skin. It is unclear if topical undecylenoyl phenylalanine is beneficial for age spots. Details: Preliminary clinical research shows that applying undecylenoyl phenylalanine 2% cream to age spots, also known as solar lentigines, twice daily for 12 weeks significantly reduces the number of spots or their pigmentation when compared with controls (92704).
Alcohol use disorder. Oral DL-phenylalanine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients experiencing alcohol withdrawal symptoms shows that taking a combination of DL-phenylalanine 300 mg, L-glutamine 150 mg, and 5-HTP 5 mg orally daily for 40 days improves depression, hostility, and physical symptoms caused by psychological distress, when compared with placebo (30100).
Depression. It is unclear if oral phenylalanine is beneficial in patients with depression. Details: Older clinical research conducted prior to 1985 suggests that taking L-phenylalanine 250 mg orally or intravenously daily for 14-96 days in combination with selegiline, or DL-phenylalanine 50-200 mg orally daily for 15-30 days, might improve symptoms of depression (2468,2469,68795,68825). However, taking D-phenylalanine, 50-100 mg daily for 15 days, does not seem to provide any benefit (68795,68830).
Multiple sclerosis (MS). Oral L-phenylalanine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that treatment with Cari Loder's regimen, which includes oral L-phenylalanine and lofepramine, plus intramuscular (IM) vitamin B12 for 24 weeks, does not improve disability in patients with MS when compared with placebo plus IM vitamin B12 (68796).
Obesity. It is unclear if oral L-phenylalanine is beneficial in obese or overweight patients. Details: Preliminary clinical research in females with overweight or obesity shows that taking L-phenylalanine 5 grams or 10 grams orally 20 minutes before meals twice daily does not reduce energy intake or improve satiety when compared with placebo (92705).
Osteoarthritis. Although there is interest in using oral phenylalanine for osteoarthritis, there is insufficient reliable information about the clinical effects of phenylalanine for this condition.
Pain (acute). It is unclear if oral D-phenylalanine is beneficial for acute pain. Details: Preliminary clinical research shows that taking D-phenylalanine 2-4 grams orally as a single dose 30 minutes prior to tooth extraction modestly enhances the analgesic effects of acupuncture when compared with acupuncture alone (2456).
Parkinson disease. Although there is interest in using oral phenylalanine for Parkinson disease, there is insufficient reliable information about the clinical effects of phenylalanine for this condition.
Rheumatoid arthritis (RA). Although there is interest in using oral phenylalanine for RA, there is insufficient reliable information about the clinical effects of phenylalanine for this condition. More evidence is needed to rate phenylalanine for these uses.

TAURINE

Congestive heart failure (CHF). Oral taurine may improve left ventricular function, heart failure-related symptoms, and exercise capacity in patients with CHF. Details: Taking taurine 2-6 grams in two or three divided doses daily for 6-8 weeks seems to improve left ventricular function (5248,5271,8221) and symptoms of heart failure (5271,5306,8221) when compared with placebo or coenzyme Q10 in patients with New York Heart Association (NYHA) functional class II to IV. Also, taking taurine 500 mg three times daily for 2 weeks seems to improve exercise capacity when compared with placebo in patients with heart failure (77176). Some patients with severe heart failure rapidly improve from NYHA class IV to II after 4-8 weeks of treatment. Improvement seems to continue for as long as taurine treatment is continued, up to one year (5306,8217,8218,8221).
Hepatitis. Oral taurine may improve liver function in patients with acute or chronic hepatitis. Details: Several small clinical trials show that taking taurine 1.5-4 grams daily for up to 3 months improves liver function in patients with acute and chronic hepatitis when compared with placebo (10454,77114,77147).

Obesity. Oral taurine does not appear to improve body weight in adults who are obese or overweight. Details: A meta-analysis of 12 small clinical trials shows that taurine supplementation does not reduce body weight or body mass index (BMI) when compared with placebo. The studies included in this analysis evaluated taurine doses of 0.5-6 grams daily for 15 days to 6 months. Most of the patient populations evaluated in the included studies had liver or metabolic disorders; three studies specifically evaluated overweight or obese adults (104166). Additionally, a more recent clinical trial in a small group of females with obesity shows that taking taurine 1 gram three times daily along with a calorie-restricted diet for 8 weeks does not reduce body weight, BMI, or waist circumference when compared with calorie restriction alone (104167). In contrast, a very small study in adults with type 2 diabetes on antidiabetes medication shows that taking taurine 500 mg twice daily for 8 weeks reduces body mass, BMI, and body fat percentage when compared with control (112271). The validity of these effects is limited by the small sample size.

Academic performance. It is unclear if oral taurine is beneficial to improve academic performance. Details: A very small clinical study in college entrance examinees over age 19 shows that taking a jelly containing taurine 3 grams daily for 14 days does not improve academic achievement when compared with baseline or placebo (110579). Due to its small size, this study may have been inadequately powered to detect a difference between groups.
Age-related macular degeneration (AMD). Although there has been interest in using oral taurine for AMD, there is insufficient reliable information about the clinical effects of taurine for this purpose.
Androgenic alopecia. Oral taurine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A moderate-sized clinical study in adults with androgenic alopecia or telogen effluvium shows that taking a combination product containing taurine, cysteine, methionine, iron, selenium, and hydrolyzed collagen (GFM Oral, Cantabria Labs) along with conventional therapy, consisting primarily of finasteride or minoxidil, daily for 12 weeks improves hair loss when compared with conventional therapy alone (111636). It is unclear if this effect is due to taurine, other ingredients, or the combination.
Athletic performance. Research on the use of taurine for improving endurance or power output is limited and conflicting; however, it may improve performance by a small amount in some athletes. Details: Research is conflicting on the effects of taurine on athletic performance. Several clinical studies in trained and untrained athletes show that taking taurine 1-6 grams as a single dose before endurance exercise, or 3 grams daily for 8 weeks after endurance exercise, does not improve endurance or aerobic capacity when compared with placebo (77159,77203,95613,98334). However, a meta-analysis of 7 small clinical trials shows that taking taurine 1-6 grams daily for up to 2 weeks slightly improves endurance when compared with control. Also, preliminary studies in male cyclists, recreationally active males, Olympic-level athletes, and female athletes habituated to caffeine show that taking taurine 50 mg/kg or 1-6 grams one time 1.5-2 hours prior to a cycling test increases the time to exhaustion and peak, mean, and minimum power output but does not improve perceived exertion, fatigue index, heart rate, or anaerobic capacity when compared with placebo (101475,103211,112265,112269). The reasons for these discrepancies are unclear; the meta-analysis did not identify a dose or duration-related benefit. One small clinical trial shows that taking taurine 40 mg/kg improves muscle power in caffeine-deprived athletes who regularly use caffeine, but actually seems to worsen muscle power in athletes who do not regularly use caffeine (98335). Overall, it is not clear which population is most likely to benefit from taurine use (98337,98338). Study results are mixed when taurine has been evaluated in combination with other ingredients. One small study shows that taking a specific product containing taurine and caffeine (AdvoCare Spark) does not improve sprint performance in college athletes when compared with placebo (77195). However, other small studies of cyclists and boxers suggest that taking taurine in combination with a variety of other ingredients including B vitamins, caffeine, and glucuronolactone (Red Bull Energy Drink) or ginseng, kudzu, and soybean, may improve measures such as endurance, power, balance, or agility (37815,57945,110577,112269). It is unclear if the benefits seen in these studies are due to taurine, other ingredients, or the combinations.
Attention deficit-hyperactivity disorder (ADHD). Although there has been interest in using oral taurine for ADHD, there is insufficient reliable information about the clinical effects of taurine for this purpose.
Autism spectrum disorder. Although there has been interest in using oral taurine for autism spectrum disorder, there is insufficient reliable information about the clinical effects of taurine for this purpose.
Chemotherapy-induced nausea and vomiting (CINV). It is unclear if oral taurine is beneficial in patients with CINV. Details: One small clinical trial in patients with acute lymphoblastic leukemia receiving 6 months of chemotherapy shows that taking taurine (pure powder, Aviforme) 1000 mg twice daily, starting 6 hours after receiving chemotherapeutic agents, significantly improves CINV in 87.5% of patients. Other symptoms, such as reduced appetite and smell and taste impairment, are also improved in some patients (91512).
Chemotherapy-induced nephrotoxicity. It is unclear if oral taurine is beneficial for preventing or treating chemotherapy-induced nephrotoxicity. Details: One small clinical trial in patients with acute lymphoblastic leukemia receiving 6 months of chemotherapy shows that taking taurine (pure powder, Aviforme) 1000 mg twice daily reduces plasma creatinine, urea, bilirubin, and liver enzymes after 4 months when compared with placebo. This suggests a protective effect against chemotherapy-induced nephrotoxicity and hepatotoxicity. A reduction in overall fatigue is also observed (95616).
Cirrhosis. It is unclear if oral taurine is beneficial in patients with cirrhosis. Details: One small, uncontrolled clinical study in patients with cirrhosis shows that taking taurine 1 gram three times daily for 4 weeks reduces the severity and frequency of muscle cramps when compared to baseline (104165). Another small clinical trial in patients with cirrhosis shows that taking taurine 6 grams daily for 4 weeks reduces portal hypertension by 12%, compared with a 2% increase in the placebo group (98336). However, it is unclear if this is associated with a reduced risk for complications such as variceal bleeding and ascites.
Cognitive function. It is unclear if oral taurine is beneficial for improving cognitive function; however, taking an energy drink (Red Bull Energy Drink) containing taurine and other ingredients may modestly improve some measures of cognitive function. Details: Levels of taurine decrease with age, but supplementation does not seem to have neuroprotective effects or cognitive benefits in the elderly (101471,110574,110578). In one small crossover study, taurine alone did not reduce errors in sleep-deprived individuals when compared with placebo (38154). However, taurine taken as part of an energy drink formulation containing taurine, caffeine, glucuronolactone, and B vitamins (Red Bull Energy Drink) improves focused and sustained attention, wakefulness, verbal reasoning, driving ability and quality, and reaction speed when compared with placebo (9899,38117,77088,77202). Preliminary clinical research in young adults also shows that consuming the Red Bull Energy Drink might improve attention and verbal reasoning, but does not seem to improve memory, when compared with placebo (9899,77088).
Cystic fibrosis. Oral taurine may reduce steatorrhea in children with cystic fibrosis, but it does not seem to improve other measures of nutritional status. Details: Some small clinical studies in children with cystic fibrosis show that taking taurine 30-40 mg/kg daily for 7 days to 6 months might be useful as adjunctive therapy to reduce steatorrhea when compared with baseline or placebo (10455,77227,77231). However, it does not seem to improve growth, lung function, muscle protein breakdown, or other symptoms of cystic fibrosis (77224,77228). Also, adding taurine 500-1500 mg daily to treatment with ursodeoxycholic acid for up to one year does not improve liver function tests, fat absorption, or nutritional status in patients with cystic fibrosis and associated liver disease when compared with ursodeoxycholic acid alone (77246,77256).
Delirium. It is unclear if oral taurine prevents delirium in patients in the intensive care unit. Details: A large clinical study of hospitalized adults in Iran who underwent liver transplantation shows that taking a specific taurine powder product (100% Taurine Amino Acid, MyProtein) 2 grams daily for 30 days post-transplant reduces the risk of delirium by 73% when compared with placebo. These results also suggest that for every four patients treated with taurine over placebo, one additional case of delirium is prevented. Patients who took taurine also had less time on the ventilator and shorter intensive care and hospital stays (110575). However, it is unclear if these effects are due to taurine or other factors since ventilator time and intensive care length of stay are risk factors for delirium.
Diabetes. It is unclear if oral taurine is beneficial in patients with diabetes. Details: Plasma levels of taurine are reported to be lower in patients with diabetes than in healthy controls (101473). However, clinical research evaluating taurine for glycemic control is mixed (77074,103212). One small clinical trial in patients with type 2 diabetes shows that taking taurine 1 gram three times daily for 8 weeks reduces blood glucose, insulin resistance, total cholesterol, and low-density lipoprotein (LDL) cholesterol when compared with placebo (103212). Although there was no improvement in glycated hemoglobin (HbA1c), the study was not long enough to detect a meaningful reduction in HbA1c. Other preliminary clinical research shows that taking taurine 1-1.5 grams twice daily for 2-4 months does not affect fasting blood glucose, HbA1c, or insulin but may improve measures of insulin resistance in patients with type 2 diabetes when compared with placebo (77074,112271). However, taking taurine while following an exercise program 3 times weekly does appear to reduce fasting blood sugar and HbA1c when compared with exercise plus placebo (112271). The reasons for these discrepant findings are unclear; however, all the included studies were small and potentially inadequately powered to detect a difference in outcomes.
Epilepsy. Although there has been interest in using oral taurine for epilepsy, there is insufficient reliable information about the clinical effects of taurine for this condition.
Exercise-induced muscle soreness. Small clinical studies suggest that oral taurine may modestly improve exercise-induced muscle soreness. Details: One small clinical trial in healthy, untrained adults shows that taking taurine 2 grams in combination with branched chain amino acids (BCAAs) three times daily for 2 weeks reduces subjective muscle soreness by 37% when compared with placebo (77212). Another small clinical trial in young, untrained males shows that taking taurine (Taisho Pharmaceutical Co., LTD.) 2 grams three times daily after meals before exercise, and continuing for three days after exercise, reduces delayed onset muscle soreness (DOMS), but not creatine kinase levels, when compared with placebo (91513).
Fatigue. It is unclear if oral taurine is beneficial for improving fatigue. Details: One small clinical trial shows that taurine seems to reduce fatigue when taken alone, but increases fatigue when taken in combination with caffeine (77202). However, an observational study in young adults has found that subjective scores for physical and mental fatigue do not seem to correlate with dietary taurine intake (101472). One small clinical trial shows that drinking 500 mL of an energy drink providing taurine 1 gram plus other ingredients including caffeine and B vitamins decreases measures of driving-related fatigue in a driving simulation when compared with placebo (91075).
Helicobacter pylori. It is unclear if oral taurine can aid in the eradication of helicobacter pylori (H. pylori). Details: One clinical trial shows that taking taurine 500 mg twice daily in combination with conventional treatment for 6 weeks increases H. pylori eradication and shortens duodenal ulcer scarring time in patients with confirmed H. pylori infection when compared with conventional treatment alone (77145).
Hyperlipidemia. It is unclear if oral taurine is beneficial for lowering lipid levels. Details: A meta-analysis of 12 small clinical trials in adults with various liver or metabolic disorders, but without a specific diagnosis of hyperlipidemia, shows that taurine supplementation reduces total cholesterol by 11 mg/dL and triglycerides by 13 mg/dL, but does not seem to improve low-density lipoprotein (LDL) cholesterol or high-density lipoprotein (HDL) cholesterol levels, when compared with placebo. The studies included in this analysis evaluated doses of 0.5-6 grams daily for 15 days to 6 months (104166). The benefits of taurine in adults with hyperlipidemia are unclear. The effect of taurine has also been investigated in combination with exercise. A very small study in adults with type 2 diabetes on antidiabetes medication shows that taking taurine 500 mg twice daily while participating in an exercise program 3 times weekly for 8 weeks reduces triglycerides, total cholesterol, and LDL cholesterol and increases HDL cholesterol when compared with exercise plus placebo (112271).
Hypertension. Oral taurine may modestly reduce blood pressure in patients with hypertension; however, the long-term antihypertensive effects of taurine are unclear. Details: One clinical study in patients with elevated blood pressure or stage 1 hypertension shows that taking taurine 1.6 grams daily for 12 weeks reduces systolic blood pressure (SBP) by 5 mmHg and diastolic blood pressure (DBP) by 3 mmHg when compared with placebo. The benefit is seen after 8 weeks of continued supplementation (95614). A small clinical trial in patients with stage 2 hypertension (previously classified as borderline hypertension) shows that taking taurine 6 grams daily for 7 days reduces both SBP and DBP when compared to baseline (77229). The long-term effects of taurine on blood pressure are unclear. A meta-analysis of 12 small clinical trials in adults with various liver or metabolic disorders, but without a specific hypertension diagnosis, shows that taurine supplementation reduces SBP by 5 mmHg and DBP by 3 mmHg when compared with placebo. The studies included in this analysis evaluated doses of 0.5-6 grams daily for 15 days to 6 months (104166). Taurine is commonly found in energy drinks, and its effect on blood pressure when used in combination with other ingredients in the form of an energy drink has been evaluated. A small observational study in young adults suggests that drinking a specific combination product containing taurine 100 mg, caffeine, and group B vitamins (Redbull Energy Drink) reduces heart rate but does not change SBP or DBP when compared to baseline (112266). However, another small observational study in young healthy adults suggests that drinking a specific combination product containing taurine 2000 mg, caffeine, ginseng, glucuronolactone, inositol, guarana, L-carnitine, and B vitamins (Monster Energy Drink) increases both SBP and DBP by about 16 mmHg and raises heart rate by 17 beats per minute 15 minutes after consumption when compared to baseline. However, 90 minutes after consumption only DBP and heart rate remain elevated (112268). In both studies, the validity of the effects is limited by a lack of a comparator group. Additionally, it is unclear if the effects are due to taurine, other ingredients, or the combination.
Infant development. Higher maternal intake of taurine from the diet may be linked to increased newborn length and weight; however, feeding taurine-containing formula to newborns does not appear to improve infant development. Details: One observational study has found a positive correlation between maternal dietary taurine intake and newborn length. In pregnant patients with high taurine intake (>120 mg/day), neonatal birth weight and length were significantly higher when compared with groups with lower taurine intake (101474). However, clinical research shows that administering infant formula containing taurine 45 mg/L for up to 12 weeks does not affect weight, length, head circumference, or behavior in preterm and full-term infants when compared with formula without taurine (77119,77216,77218,77239,77260).
Iron deficiency anemia. It is unclear if oral taurine is beneficial in patients with iron deficiency anemia. Details: One small clinical trial in females with iron deficiency anemia shows that taking taurine 1000 mg plus ferrous sulfate 325 mg daily for 20 weeks improves hemoglobin concentrations, red blood cell counts, and serum ferritin levels when compared with ferrous sulfate plus placebo (77070).
Muscular dystrophy. It is unclear if oral taurine is beneficial in patients with muscular dystrophy. Details: One very small crossover trial in patients with muscular dystrophy shows that taking taurine 100-150 mg/kg for 6 months improves the ability to relax muscles after voluntary use when compared with placebo (77235).
Physical performance. It is unclear if oral taurine improves physical performance in older adults. Details: A small study in elderly females living in a care facility shows that taking taurine powder 1.5 grams daily for 14 weeks in addition to standardized exercise training may modestly improve some measures of physical fitness (i.e. agility, endurance) when compared to baseline. These measures were not improved in patients who took taurine but did not participate in exercise training or who participated in exercise training but did not take taurine (110574). The validity of these findings is limited by lack of randomization, blinding, and statistical comparison between groups.
Postoperative recovery. It is unclear if oral taurine is beneficial for improving postoperative recovery. Details: One small clinical trial in patients recovering from surgery after a hip fracture shows that taking taurine 6 grams daily for 7 days after surgery does not improve morbidity and mortality outcomes after 1 year when compared with placebo (95615).
Psychosis. It is unclear if oral taurine is beneficial in patients with psychosis. Details: One small clinical trial in adults up to 25 years of age with first-episode psychosis shows that taking taurine 4 grams daily for 12 weeks in combination with prescribed antipsychotics reduces positive psychotic symptoms, but not negative or cognitive symptoms, when compared with placebo (95612).
Sleep deprivation. Oral taurine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking a combination product containing taurine, caffeine, glucuronolactone, and B vitamins (Red Bull Energy Drink) reduces lane drifting and sleepiness and improves driving quality and reaction time during a car-driving simulator exercise in sleep-deprived individuals when compared with placebo (38117,77066). Other preliminary clinical research in sleep-deprived surgical trainees shows that taking taurine 2 grams in addition to caffeine 150 mg improves reaction time during performance of simulated laparoscopic surgery when compared with placebo, although error-making is not reduced (38154).
Tourette syndrome. Oral taurine may improve tic severity in children with Tourette syndrome who are taking tiapride at a dose of 300 mg or less. Taurine may not be effective in children taking higher doses of tiapride. Details: One clinical trial in children 6-16 years of age with Tourette syndrome or other tic disorders shows that taking taurine along with tiapride reduces the severity of tics when compared with tiapride alone. For every 6 children taking taurine, one additional child saw a 60% or greater reduction in tic severity as measured on the Yale Global Tic Severity Scale when compared with placebo. However, taurine did not improve tic severity in children taking tiapride at a dose greater than 300 mg daily (103210). Taurine was taken in age-dependent doses of 2.4 grams daily in those 6-8 years, 3.6 grams daily in those 9-13 years, and 4.8 grams daily in those 14-16 years.
Traumatic brain injury (TBI). It is unclear if oral taurine is beneficial in patients with a TBI. Details: A small clinical study of adults in Iran receiving treatment in the intensive care unit (ICU) following TBI shows that adding a specific taurine powder product (Nutricost) 30 mg/kg/day up to 3 grams daily to enteral nutrition for 14 days may modestly improve disease severity scores, but does not reduce days on the ventilator, ICU length of stay, or mortality at 30 days when compared with usual enteral nutrition (110573). Due to its small size, this study may have been underpowered to detect differences between groups. More evidence is needed to rate taurine for these uses.

Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). Several small clinical studies suggest that oral threonine does not improve symptoms or slow the progression of ALS. Details: Small clinical trials show that taking threonine 2 grams daily for 7 days or 4 grams daily, divided into two or four doses, for up to 12 months does not seem to slow the progression of early-stage ALS or reduce symptoms when compared with placebo (681,12057,60069). There is also concern that threonine might actually worsen pulmonary function in these patients. The decline in forced vital capacity (FVC) associated with threonine therapy was about 2.5 times greater than that with placebo (681).

Familial spastic paraparesis (FSP). It is unclear if oral threonine is beneficial in patients with FSP. Details: A small clinical study in patients with FSP shows that taking threonine 1.5 grams to 2 grams three times daily for 2 weeks slightly improves some measures of motor impairment and spasticity when compared with placebo. However, these improvements do not seem to be clinically significant (12059).
Multiple sclerosis (MS). It is unclear if oral threonine is beneficial in patients with MS. Details: A small clinical study in individuals with inactive or slowly progressive MS shows that taking threonine 2.5 grams three times daily for 8 weeks does not significantly reduce spasticity when compared with placebo (60073).
Spasticity. It is unclear if oral threonine is beneficial in patients with spasticity. Details: A small clinical study in patients with spasticity arising from spinal cord injuries, multiple sclerosis, or syringomyelia shows that taking threonine 2 grams three times daily for 2 weeks slightly improves leg muscle tone when compared with placebo (12056). However, methodological concerns limit the validity of this finding. More evidence is needed to rate threonine for these uses.

BRANCHED-CHAIN AMINO ACIDS (BCAA) (Branched Chain Amino Acids, L-Leucine, L-Isoleucine, L-Valine)

Safety view details

Below is general information about the safety of the known ingredients contained in the product Synthegen Cherry Lime. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

LIKELY SAFE ...when used orally and appropriately. BCAAs 12 grams daily have not been associated with significant adverse effects in studies lasting for up to 2 years (68,72,73,74,10117,10146,10147,37120,92643,97531,103351,103352). ...when used intravenously and appropriately. BCAAs are an FDA-approved injectable product (13309).

CHILDREN: LIKELY SAFE
when used orally in dietary amounts of 71-134 mg/kg daily (11120,13308).

CHILDREN: POSSIBLY SAFE
when larger, supplemental doses are used orally and appropriately for up to 6 months (13307,13308,37127).

PREGNANCY:
Insufficient reliable information available; avoid using amounts greater than those found in food. Although adverse effects have not been reported in humans, some animal research suggests that consumption of supplemental isoleucine, a BCAA, during the first half of pregnancy may have variable effects on birth weight, possibly due to abnormal placental development (103350).

LACTATION:
Insufficient reliable information available; avoid using amounts greater than those found in food. Although the safety of increased BCAA consumption during lactation is unclear, some clinical research suggests that a higher concentration of isoleucine and leucine in breastmilk during the first 6 months postpartum is not associated with infant growth or body composition at 2 weeks, 2 months, or 6 months (108466).

CALCIUM

LIKELY SAFE ...when used orally or intravenously and appropriately. Calcium is safe when used in appropriate doses (7555,12928,12946,95817). However, excessive doses should be avoided. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stone, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients not to consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

POSSIBLY UNSAFE ...when used orally in excessive doses. The National Academy of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 19-50 years, 2500 mg; 51 years and older, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients to not consume more than the recommended daily intake of 1000-1200 mg per day and to consider total calcium intake from both dietary and supplemental sources (17484). Also, advise patients taking calcium supplements to take calcium along with vitamin D (93533).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Calcium is safe when used in appropriate doses (17506).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (945,1586,3263,3264,17506). The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia (97347).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses. The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg (17506). Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures (97345).

LIKELY SAFE ...when used orally and appropriately. Glutamine has been safely used in clinical research in doses up to 40 grams per day or 1 gram/kg daily (2334,2337,2338,2365,5029,5462,7233,7288,7293), (52288,52307,52308,52311,52313,52337,52349,52350,96516,97366). A specific glutamine product (Endari) is approved by the US Food and Drug Administration (FDA) (96520). ...when used intravenously. Glutamine has been safely incorporated into parenteral nutrition in doses up to 600 mg/kg daily in clinical trials (2363,2366,5448,5452,5453,5454,5458,7293,52272,52275), (52283,52289,52304,52306,52316,52341), (52359,52360,52371,52377,52381,52284,52385,52408,96637,96507,96516).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Glutamine has been shown to be safe in clinical research when used in amounts that do not exceed 0.7 grams/kg daily in children 1-18 years old (11364,46657,52321,52323,52363,86095,96517). A specific glutamine product (Endari) is approved by the US Food and Drug Administration for certain patients 5 years of age and older (96520). ...when used intravenously. Glutamine has been safely incorporated into parenteral nutrition in doses up to 0.4 grams/kg daily in clinical research (52338,96508). There is insufficient reliable information available about the safety of glutamine when used in larger amounts in children.

PREGNANCY AND LACTATION: LIKELY SAFE
when consumed in amounts commonly found in foods. There is insufficient reliable information available about the safety of glutamine when used in larger amounts as medicine during pregnancy or lactation.

LIKELY SAFE ...when used orally in the amounts found in foods.

POSSIBLY SAFE ...when used orally in larger amounts, short-term. L-histidine has been used with apparent safety in doses of up to 4 grams daily for up to 12 weeks (2347,2353,96311,108621), or in doses of up to 8 grams daily for up to 4 weeks (108620).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in the amounts found in foods. There is insufficient reliable information available about the safety of histidine when used in larger amounts during pregnancy or lactation.

POSSIBLY SAFE ...when used orally and appropriately. Doses up to 3 grams or 76 mg/kg daily for up to one year have been used with apparent safety (1909,2167,2168,3374,46606,55820,55822,96637,96645,99248)(99249,102872). The International Society of Sports Nutrition states that chronic use of HMB is safe for young and old patients (96644).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

LIKELY SAFE ...when used orally and appropriately. L-carnitine has been safely used in clinical trials lasting up to 12 months (1947,3620,3621,3623,3624,3625,3626,3627,3628,3629) (3630,3639,4949,8047,9790,12352,16104,16105,16106,16107) (16109,16110,23437,26496,26499,58150,58156,58161,58169,58182) (58189,58204,58207,58209,58213,58294,58523,58554,58556,58647) (58679,58715,58778,58793,58830,58831,58882,59023,59029,59043) (90624,90633,104177,111872,111876,111883,111884,111891,111898). ...when used parenterally as an FDA-approved prescription medicine. Avoid using D-carnitine and DL-carnitine. These forms of carnitine can act as competitive inhibitors of L-carnitine and may cause symptoms of L-carnitine deficiency (1946).

CHILDREN: POSSIBLY SAFE
when used orally or intravenously and appropriately. L-carnitine has been safely used orally in children for up to 6 months (1433,3622,58166,58502,58981,59188,111887,111900). It has also been safely used orally and intravenously in preterm infants (3633,3634,3635,3636,3637,58163,58190,58800,58902,59097)(59161).

PREGNANCY:
Insufficient reliable information available; avoid using.

LACTATION: POSSIBLY SAFE
when used orally. Supplemental doses of L-carnitine have been given to infants in breast milk and formula with no reported adverse effects. The effects of large doses used while nursing are unknown, but L-carnitine is secreted in the breast milk (3616).

L-TRYPTOPHAN

LIKELY SAFE ...when used orally in the amounts commonly found in foods. L-tryptophan is an essential amino acid that must be obtained from the diet. A typical diet in the United States supplies 0.5-2 grams of L-tryptophan daily (1146).

POSSIBLY SAFE ...when used orally in medicinal amounts, short-term. L-tryptophan 5 grams daily for 21 days has been used with apparent safety (91460,97243). In 1989, L-tryptophan was linked to over 1500 reports of eosinophilia-myalgia syndrome (EMS) and several deaths (7067,8053,10085,11474,11478), leading to its removal from the U.S. market in 1990 (7067). The exact cause of EMS in patients taking L-tryptophan is unknown, but some evidence suggests that nearly all cases were due to contaminated L-tryptophan products from a single manufacturer (8050,8051,11477,11478). Under the Dietary Supplement Health and Education Act (DSHEA) of 1994, L-tryptophan is currently available and marketed as a dietary supplement. There is insufficient reliable information available about the safety of L-tryptophan when used orally, long-term.

PREGNANCY: LIKELY SAFE
when used orally in amounts commonly found in foods.

PREGNANCY: POSSIBLY UNSAFE
when used orally in medicinal amounts because it may cause respiratory depression in utero (1142). Avoid using in amounts greater than those found in foods.

LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods. There is insufficient reliable information available about the safety of larger medicinal amounts; avoid using.

POSSIBLY SAFE ...when used orally in doses up to 3000 mg daily for up to one year (1114,1119,1120,90642,104104), or up to 6000 mg daily for up to 8 weeks (90644,90645). ...when used topically and appropriately, short-term (11051).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

LIKELY SAFE ...when used orally in amounts commonly found in food (94500).

POSSIBLY SAFE ...when used orally or intravenously and appropriately in medicinal amounts under the supervision of a healthcare professional (2410,2411,2413).

POSSIBLY UNSAFE ...when used orally or intravenously in excessive doses. Doses larger than 100 mg/kg should be avoided to prevent severe and potentially lethal cerebral effects (9339).

CHILDREN: LIKELY SAFE
when used orally in amounts commonly found in foods (94500).

CHILDREN: POSSIBLY SAFE
when used intravenously and appropriately (9338).

CHILDREN: POSSIBLY UNSAFE
when used intravenously in infants receiving parenteral nutrition. In infants, blood methionine concentration can increase due to lower enzyme activity and inability to metabolize methionine. High levels of methionine can cause liver toxicity (9338).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in food (94500). There is insufficient reliable information available about the safety of methionine in medical doses during pregnancy and lactation; avoid using.

LIKELY SAFE ...when L-phenylalanine is consumed in amounts typically found in foods (11120).

POSSIBLY SAFE ...when L-phenylalanine is used orally in doses up to 100 mg/kg daily for up to 3 months (2463,2464,2466,2467,2469). ...when D-phenylalanine is used orally in doses up to 1 gram daily for up to 4 weeks, or as a single dose of 4-10 grams (2455,2456,2459,68795,104792). ...when DL-phenylalanine is used orally in doses up to 200 mg daily for up to 4 weeks (2468,68795,68825). ...when phenylalanine cream is applied topically, short-term (2461,92704).

PREGNANCY: LIKELY SAFE
when L-phenylalanine is consumed in amounts typically found in foods by pregnant patients with normal phenylalanine metabolism (2020,11120).

PREGNANCY: UNSAFE
when L-phenylalanine is consumed in amounts typically found in foods by pregnant patients with high serum phenylalanine concentrations, such as those with phenylketonuria (PKU). Serum levels of phenylalanine greater than 360 micromol/L increase the risk of birth defects (1402,11468). Experts recommend that patients with high phenylalanine serum concentrations follow a low phenylalanine diet for at least 20 weeks prior to conception to decrease the risk for birth defects (1402). There is insufficient reliable information available about the safety of L-phenylalanine when taken by mouth in large doses during pregnancy; avoid using. There is insufficient reliable information available about the safety of oral D-phenylalanine during pregnancy; avoid using.

LACTATION: LIKELY SAFE
when L-phenylalanine is consumed in amounts typically found in foods by breast-feeding patients with normal phenylalanine metabolism (2020,11120). There is insufficient reliable information available about the safety of L-phenylalanine when taken by mouth in medicinal amounts during lactation; avoid using. There is insufficient reliable information available about the safety of oral D-phenylalanine during lactation; avoid using.

TAURINE

LIKELY SAFE ...when used in amounts found in foods. Typical daily intakes for adults range from 40-400 mg (101471).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts. Taurine 2-4 grams daily in two or three divided doses has been used safely in studies lasting up to 3 months (5248,5271,8217,8221,10454,77147,95612,98337,104165,104167). Higher doses of taurine 6 grams daily have been used safely in studies lasting up to 4 weeks (98336,98337). A risk assessment of orally administered taurine has identified an Observed Safe Level (OSL) of up to 3 grams daily for healthy adults (31996).

CHILDREN: LIKELY SAFE
when used in amounts found in foods.

CHILDREN: POSSIBLY SAFE
when used orally and appropriately in medicinal amounts. Taurine 2.4-4.8 grams daily in three divided doses has been safely used in children 6-16 years of age for up to 12 weeks (103210).

PREGNANCY AND LACTATION: LIKELY SAFE
when used in amounts found in foods. There is insufficient reliable information available about the safety of taurine when used in medicinal amounts during pregnancy and lactation; avoid using.

LIKELY SAFE ...when used orally in food amounts. Threonine as L-threonine in doses of 7-14 mg/kg daily (about 0.5-1 gram daily) has been suggested to be the minimum amount required to maintain a positive nitrogen balance in humans and is generally considered to be safe (60072,94096).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts. Taking threonine in doses up to 4 grams daily for up to 12 months seems to be safe (681,12056,12057,12059,60069).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

BRANCHED-CHAIN AMINO ACIDS (BCAA) (Branched Chain Amino Acids, L-Leucine, L-Isoleucine, L-Valine)

Interactions with Drugs view details

Below is general information about the interactions of the known ingredients contained in the product Synthegen Cherry Lime. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

ANTIDIABETES DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Theoretically, BCAAs might alter the effects of antidiabetes medications.

Details

Some evidence suggests that BCAAs might stimulate insulin release (10105,10110,10113,10114,10118). However, a small clinical study in adults with liver cirrhosis and high nocturnal levels of blood glucose suggests that BCAAs might increase blood glucose levels (103348).

LEVODOPA

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

BCAAs in large doses can reduce the effects of levodopa.

Details

BCAAs may compete with levodopa for transport systems in the intestine and brain and decrease the effectiveness of levodopa (66,2719). Small clinical studies how that concomitant ingestion of protein or high doses of leucine or isoleucine (100 mg/kg) and levodopa can exacerbate tremor, rigidity, and the "on-off" syndrome in patients with Parkinson disease (3291,3292,3293,3294).

CALCIUM

ALUMINUM

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.

Details

Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease (21631). However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption (93006).

BISPHOSPHONATES

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = C

Calcium reduces the absorption of bisphosphonates.

Details

Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates (12937).

CALCIPOTRIENE (Dovonex)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Taking calcipotriene with calcium might increase the risk for hypercalcemia.

Details

Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia (12938). Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.

CALCIUM CHANNEL BLOCKERS

Interaction Rating = Minor Be watchful with this combination.

Severity = Moderate • Occurrence = Unlikely • Level of Evidence = D

Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.

Details

Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects (6124). But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers (12939,12947).

CEFTRIAXONE (Rocephin)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = D

Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.

Details

Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction (15794,21632). So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.

DIGOXIN (Lanoxin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = B

Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.

Details

Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin (12940). However, one retrospective analysis of clinical data suggests that intravenous calcium does not increase the risk of dysrhythmias or mortality in patients receiving digoxin (38960).

DILTIAZEM (Cardizem, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = D

Theoretically, calcium may reduce the therapeutic effects of diltiazem.

Details

Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.

DOLUTEGRAVIR (Tivicay)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Calcium seems to reduce levels of dolutegravir.

Details

Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation (93578).

ELVITEGRAVIR (Vitekta)

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Calcium seems to reduce levels of elvitegravir.

Details

Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation (94166).

LEVOTHYROXINE (Synthroid, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Calcium seems to reduce the absorption and effectiveness of levothyroxine.

Details

Advise patients to take levothyroxine and calcium supplements at least 4 hours apart. Calcium reduces levothyroxine absorption, probably by forming insoluble complexes (5082). Calcium carbonate supplements reduce effectiveness of levothyroxine in patients with hypothyroidism (5081,5082,6137).

LITHIUM

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.

Details

Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients (38953). Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.

QUINOLONE ANTIBIOTICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Calcium seems to reduce the absorption of quinolone antibiotics.

Details

Advise patients to take oral quinolones at least 2 hours before or 4-6 hours after calcium supplements or calcium-fortified foods. Taking calcium at the same time as oral quinolones can reduce quinolone absorption. Calcium binds to quinolones in the gut (4412,10339,21638,38570).

RALTEGRAVIR (Isentress)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = B

Calcium may reduce levels of raltegravir.

Details

Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir (94164). However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure (94165).

SOTALOL (Betapace)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = B

Calcium seems to reduce the absorption of sotalol.

Details

Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes (10018).

TETRACYCLINE ANTIBIOTICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = C

Calcium seems to reduce the absorption of tetracycline antibiotics.

Details

Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut (1843).

THIAZIDE DIURETICS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = C

Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.

Details

Thiazides reduce calcium excretion by the kidneys (1902). Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.

VERAPAMIL (Calan, others)

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = D

Theoretically, calcium may reduce the therapeutic effects of verapamil.

Details

Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.

ANTICONVULSANTS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, glutamine might antagonize the effects of anticonvulsant medications.

Details

Glutamine is metabolized to the excitatory neurotransmitter glutamate. Glutamate might have antagonistic effects with anticonvulsant drugs (7292,7293,7294). However, this interaction has not yet been reported in humans.

None known.

None known.

ACENOCOUMAROL (Sintrom)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, L-carnitine might increase the anticoagulant effects of acenocoumarol.

Details

L-carnitine might enhance the anticoagulant effects of acenocoumarol, an oral anticoagulant similar to warfarin, but shorter-acting (9878,12165). There are at least two case reports of INR elevation with concomitant use. In one case, a 33-year-old male with a previously stable INR had an elevated INR of 4.65 after L-carnitine was started and continued for 10 weeks. INR normalized after discontinuation of the L-carnitine-containing product (12165).

THYROID HORMONE

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = B

Theoretically, L-carnitine might decrease the effectiveness of thyroid hormone replacement.

Details

L-carnitine appears to act as a peripheral thyroid hormone antagonist by inhibiting entry of thyroid hormone into the nucleus of cells (12761). Taking L-carnitine also seems to diminish some of the symptoms of hyperthyroidism (8047).

WARFARIN (Coumadin)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, L-carnitine might increase the anticoagulant effects of warfarin.

Details

L-carnitine might increase the anticoagulant effects of acenocoumarol, a shorter-acting oral anticoagulant similar to warfarin (9878,12165). There is not enough information to know whether this interaction occurs with L-carnitine and warfarin.

L-TRYPTOPHAN

CNS DEPRESSANTS

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Theoretically, concomitant use of L-tryptophan with CNS depressants might cause additive sedative effects.

Details

Clinical research shows that L-tryptophan can cause fatigue and drowsiness (1143).

SEROTONERGIC DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, combining L-tryptophan with serotonergic drugs might cause additive serotonergic effects.

Details

L-tryptophan is a precursor to serotonin (1141). Theoretically, combining serotonergic drugs with L-tryptophan might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders (8056).

5-HT4 AGONISTS

Interaction Rating = Minor Be watchful with this combination.

Severity = Mild • Occurrence = Unlikely • Level of Evidence = D

Theoretically, lysine may reduce the effects of 5-HT4 agonists.

Details

Animal research suggests that L-lysine is a partial serotonin receptor 4 (5-HT4) antagonist and inhibits diarrhea induced by the 5-HT4 agonist, 5-hydroxytryptophane (19400).

None known.

BACLOFEN

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Possible • Level of Evidence = D

Concomitant intake of phenylalanine may reduce the intestinal absorption of baclofen.

Details

Phenylalanine and baclofen share the same intestinal carrier for absorption; phenylalanine competitively inhibits the absorption of baclofen, reducing its plasma levels (23788).

LEVODOPA

Interaction Rating = Major Do not take this combination.

Severity = High • Occurrence = Probable • Level of Evidence = B

Phenylalanine, especially in high doses, can reduce the effectiveness of levodopa.

Details

Phenylalanine competes with levodopa for carrier-mediated transport into the brain. The resulting reduction in levels of levodopa in the brain can exacerbate tremor, rigidity, and the "on-off" phenomenon in patients with Parkinson disease (3291,3294).

MONOAMINE OXIDASE INHIBITORS (MAOIs)

Interaction Rating = Moderate Be cautious with this combination.

Severity = High • Occurrence = Possible • Level of Evidence = D

Theoretically, concomitant use of L-phenylalanine and non-selective MAOIs might increase the risk of hypertensive crisis.

Details

L-phenylalanine is metabolized to tyrosine (2052,9949). Some evidence suggests that L-phenylalanine, given with the non-selective MAOI pargyline, might prevent the elimination of tyramine, increasing the risk of hypertensive crisis (2021). However, this was not reported in a small number of patients when using L-phenylalanine with the partially selective MAO-B inhibitor, selegiline (2469).

TAURINE

ANTIHYPERTENSIVE DRUGS

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = D

Theoretically, taurine might increase the risk of hypotension when taken with antihypertensive drugs.

Details

Some clinical evidence suggests that taurine can reduce both systolic and diastolic blood pressure (77229,95614,104166).

LITHIUM

Interaction Rating = Moderate Be cautious with this combination.

Severity = Moderate • Occurrence = Probable • Level of Evidence = D

Theoretically, taurine might reduce excretion and increase plasma levels of lithium.

Details

Taurine is thought to have diuretic properties (3647), which might reduce the excretion of lithium.

NMDA ANTAGONISTS

Interaction Rating = Major Do not take this combination.

Severity = Moderate • Occurrence = Likely • Level of Evidence = B

Theoretically, threonine might decrease the effects of NMDA antagonists.

Details

Threonine increases central nervous system (CNS) glycine levels (12058). Glycine seems to bind a site on NMDA receptors and enhance the activity of the receptors (681,12057).

Report an Adverse Reaction to Synthegen Cherry Lime

Adverse Effects view details

Below is general information about the adverse effects of the known ingredients contained in the product Synthegen Cherry Lime. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.

BRANCHED-CHAIN AMINO ACIDS (BCAA) (Branched Chain Amino Acids, L-Leucine, L-Isoleucine, L-Valine)

General ...Orally or intravenously, BCAAs are generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal distension, diarrhea, nausea, vomiting.
All routes of administration: High doses can lead to fatigue and loss of motor coordination.

Cardiovascular ...Orally, a single case of hypertension following the use of BCAAs has been reported (37143).

Dermatologic ...Orally, a single case of skin blanching following the use of BCAAs has been reported (681). It is not known if this effect was due to use of BCAAs or other factors.

Gastrointestinal ...Orally, BCAAs can cause nausea, vomiting, diarrhea, and abdominal distension. Nausea and diarrhea has been reported to occur in about 10% of people taking BCAAs (10117,37143,92643,97531).

Neurologic/CNS ...Orally and intravenously, BCAAs can cause fatigue and loss of motor coordination due to increased plasma ammonia levels (693,694,10117). Short-term use of 60 grams of BCAAs containing leucine, isoleucine, and valine for 7 days in patients with normal metabolic function seems to increase levels of ammonia, but not to toxic plasma levels (10117). However, liver function should be monitored with high doses or long-term use (10117). Due to the potential of increased plasma levels of ammonia and subsequent fatigue and loss of motor coordination, BCAAs should be used cautiously before or during activities where performance depends on motor coordination (75). Orally, BCAAs may also cause headache, but this has only been reported in one clinical trial (681).

CALCIUM

General ...Orally and intravenously, calcium is well-tolerated when used appropriately.
Most Common Adverse Effects:
Orally: Belching, constipation, diarrhea, flatulence, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about calciphylaxis and kidney stones.

Cardiovascular ...There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these results, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of CVD, CHD, or MI (93533,107231). Also, the association between calcium supplementation and CVD, CHD, or MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482). To minimize the possible risk of CVD, CHD, or MI, advise patients not to consume more than the recommended daily intake of 1000-1200 mg and to consider total calcium intake from both dietary and supplemental sources (17484). While dietary intake of calcium is preferred over supplemental intake, advise patients who require calcium supplements to take calcium along with vitamin D, as this combination does not appear to be associated with an increased risk of MI (93533).
Rarely, calcium intake can increase the risk of calciphylaxis, which usually occurs in patients with kidney failure. Calciphylaxis is the deposition of calcium phosphate in arterioles, which causes skin ulcers and skin necrosis. In a case report, a 64-year-old female with a history of neck fracture, sepsis, and ischemic colitis presented with painful leg ulcers due to calciphylaxis. She discontinued calcium and vitamin D supplementation and was treated with sodium thiosulfate and supportive care (95816).

Gastrointestinal ...Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea (1824,1843,12950,38803). Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect (1824,1843,1844,1845,12950,38978). Calcium carbonate has been reported to cause acid rebound, but this is controversial (12935,12936).

Oncologic ...There is some concern that very high doses of calcium might increase the risk of prostate cancer. Some epidemiological evidence suggests that consuming over 2000 mg/day of dietary calcium might increase the risk for prostate cancer (4825,12949). Additional research suggests that calcium intake over 1500 mg/day might increase the risk of advanced prostate cancer and prostate cancer mortality (14132). Consumption of dairy products has also been weakly linked to a small increase in prostate cancer risk (98894). However, contradictory research suggests no association between dietary intake of calcium and overall prostate cancer risk (14131,14132,104630). More evidence is needed to determine the effect of calcium, if any, on prostate cancer risk.

Renal ...Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years (93943).

General ...Orally and intravenously, glutamine is generally well tolerated.
Most Common Adverse Effects:
Orally: Belching, bloating, constipation, cough, diarrhea, flatulence, gastrointestinal pain, headache, musculoskeletal pain, nausea, and vomiting.

Endocrine ...One case of hot flashes has been reported in a patient taking glutamine 5-15 grams orally twice daily for up to 1 year (96520).

Gastrointestinal ...Orally, glutamine has been associated with belching, bloating, constipation, flatulence, nausea, vomiting, diarrhea, and gastrointestinal (GI) pain. Nausea, vomiting, constipation, diarrhea, and GI pain have been reported in clinical trials using high-dose glutamine 10-30 grams (0.3 grams/kg) in two divided doses daily to treat sickle cell disease (99414). One case of dyspepsia and one case of abdominal pain have been reported in patients taking glutamine 5-15 grams twice daily orally for up to 1 year (96520). In a small trial of healthy males, taking a single dose of about 60 grams (0.9 grams/kg of fat free body mass [FFM]) was associated with a 50% to 79% incidence of GI discomfort, nausea, and belching, compared with a 7% to 28% incidence with a lower dose of about 20 grams (0.3 gram/kg FFM). Flatulence, bloating, lower GI pain, and urge to regurgitate occurred at similar rates regardless of dose, and there were no cases of heartburn, vomiting, or diarrhea/constipation (105013). It is possible that certain GI side effects occur only after multiple doses of glutamine.

Musculoskeletal ...Orally, glutamine 30 grams daily has been associated with cases of musculoskeletal pain and non-cardiac chest pain in clinical trials for patients with sickle cell disease (99414).

Neurologic/CNS ...Orally, glutamine has been associated with dizziness and headache. A single case of dizziness has been reported in a patient treated with oral glutamine 0.5 grams/kg. However, the symptom resolved after reducing the dose to 0.25 grams/kg (91356). Mania and hypomania have been reported in 2 patients with bipolar disorder taking commercially purchased glutamine up to 4 grams daily (7291). Glutamine is metabolized to glutamate and ammonia, both of which might have neurological effects in people with neurological and psychiatric diseases or in people predisposed to hepatic encephalopathy (7293).

Oncologic ...There is some concern that glutamine might be used by rapidly growing tumors and possibly stimulate tumor growth. Although tumors may utilize glutamine and other amino acids, preliminary research shows that glutamine supplementation does not increase tumor growth (5469,7233,7738). In fact, there is preliminary evidence that glutamine might actually reduce tumor growth (5469).

Other ...Orally, glutamine has been associated with cough when a powdered formulation is used. It is unclear if this was due to accidental inhalation. One case of a burning sensation and one case of hypersplenism has been reported in a patient taking glutamine 5-15 grams twice daily orally for up to 1 year (96520).

General ...Orally, histidine has been used with apparent safety in clinical research; however, a thorough evaluation of safety outcomes has not been conducted.

General ...Orally, HMB seems to be well tolerated.

Cardiovascular ...Orally, high blood pressure has been reported in one person taking HMB in a clinical trial (108770).

Dermatologic ...Orally, itching has been reported in two people taking HMB in clinical trials (99245,102872).

Gastrointestinal ...Orally, abdominal pain, constipation, dyspepsia, flatulence, heartburn, and nausea have been reported rarely in people taking HMB in clinical trials (99245,102872,108770).

Genitourinary ...Orally, increased urinary frequency has been reported in two people taking HMB in a clinical trial (108770).

General ...Orally and intravenously, L-carnitine is generally well tolerated.
Most Common Adverse Effects:
All routes of administration: Abdominal cramps, abdominal pain, diarrhea, gastritis, heartburn, nausea, reduced appetite, and vomiting. A fish-like body odor has also been reported.
Serious Adverse Effects (Rare):
All routes of administration: Seizures.

Cardiovascular ...According to population research, plasma L-carnitine levels are associated with increased risk of cardiovascular disease and major cardiac events (90635). However, oral supplementation with L-carnitine does not appear to be associated with an increased risk of cardiovascular disease. In fact, a meta-analysis of clinical research shows that L-carnitine supplementation is associated with a reduction in all-cause mortality, as well as ventricular arrhythmias and the development of angina and does not increase the development of heart failure or myocardial reinfarction (59037). Also, another meta-analysis suggests that L-carnitine does not affect mortality or cardiovascular outcomes in patients with a previous myocardial infarction (90630).

Dermatologic ...Orally, L-carnitine has been reported to cause skin rash in a small number of cases (16105,91724). Two patients in a hair growth study using topical carnitine reported mild itching and increased dandruff, while a third reported strong itching with reddish bumps and a burning sensation (58390). When a specific formulation containing L-carnitine, licochalcone, and 1,2-decanediol was applied to the face, mild skin dryness and tightness was reported by 12% of volunteers, compared with 4% to 8% of those in the vehicle-only control group (26493).

Gastrointestinal ...Orally and intravenously, L-carnitine has been associated with nausea, epigastric discomfort, vomiting, abdominal cramps, heartburn, gastritis, anorexia, and diarrhea (3616,3624,59030,95069,95070,101562,107410,111870,111887,111891). Orally, diarrhea or colitis symptoms (1433,3630,16105,16107,16111,23437,58523,58554,59020,90623), nausea and abdominal pain (16105,16106,26499,58169,58392,58554,90623,90634), indigestion (26703), and constipation (58523) have been reported in various clinical trials.

Hematologic ...In one case report, L-carnitine 990 mg twice daily was started in a female presenting to hospital with valproic acid toxicity. Blood phosphorous levels subsequently fell from 2.3 mg/dL to 1.3 mg/dL over 4 days. After discontinuation of L-carnitine, blood phosphorus levels increased to 1.8 mg/dL. The authors suggested that the role of L-carnitine in improved protein metabolism may play a role in the declining levels of phosphorous in the blood and increased risk of hypophosphatemia (90628).

Neurologic/CNS ...Orally or intravenously, L-carnitine has been associated with seizures (3616). Orally, use of L-carnitine in clinical trials has resulted in headache, although this event is rare (58554,95070,111891). L-carnitine may also cause agitation (95070).

Other ...Orally or intravenously, L-carnitine has been associated with a fish-like body odor (1433,3616,58166,59854,90623). One of its metabolites, trimethylamine N-oxide, can cause the urine, breath, and sweat to have a fishy odor (12756,58664).

L-TRYPTOPHAN

General ...Orally, L-tryptophan is generally well tolerated.
Most Common Adverse Effects:
Orally: Belching, diarrhea, drowsiness, dry mouth, flatulence, headache, heartburn, lightheadedness, nausea, stomach pain, visual blurring, and vomiting.
Serious Adverse Effects (Rare):
Orally: L-tryptophan has been associated with the neurological disorder eosinophilia-myalgia syndrome (EMS). However, almost all cases were traced to L-tryptophan produced by a single manufacturer in Japan and are likely related to contamination.

Cardiovascular ...Orally, L-tryptophan has been associated with eosinophilia-myalgia syndrome (EMS), which can include cardiovascular symptoms such as myocarditis, arrhythmias, and palpitations (8053,11477).

Dermatologic ...Orally, L-tryptophan has been associated with eosinophilia-myalgia syndrome (EMS), which can include dermatological symptoms such as sclerodermiform skin changes, alopecia, and rash (8053,11477).

Gastrointestinal ...Orally, L-tryptophan can cause gastrointestinal side effects such as heartburn, stomach pain, belching and flatulence, nausea, vomiting, diarrhea, dry mouth, and anorexia (10853,99884).

Hematologic ...Orally, L-tryptophan has been associated with eosinophilia-myalgia syndrome (EMS), which can include hematologic symptoms such as eosinophilia (8053,11477).

Hepatic ...Orally, L-tryptophan has been associated with eosinophilia-myalgia syndrome (EMS), which can include hepatic symptoms such as hepatomegaly (8053,11477).

Musculoskeletal ...Orally, L-tryptophan has been associated with eosinophilia-myalgia syndrome (EMS), which can include musculoskeletal symptoms such as myalgia and inflammation of the joints and connective tissue (8053,11477).

Neurologic/CNS ...Orally, L-tryptophan can cause headache, lightheadedness, and ataxia (10853,99884).
In 1989, more than 1500 cases of the neurological disorder EMS were associated with oral L-tryptophan use in the US. About 95% of all EMS cases were traced to contaminated L-tryptophan produced by a single manufacturer in Japan (8054,10288,10289,11475,11476). In 1990, L-tryptophan was recalled in the U.S. and an FDA alert was put into force limiting the importation of all over-the-counter L-tryptophan products (7067,11477,11478). After the limitation of L-tryptophan products, the incidence of EMS dropped abruptly (11474). Symptoms of EMS associated with L-tryptophan use include intense eosinophilia; fatigue; myalgia; neuropathy; sclerodermiform skin changes; alopecia; rash; and inflammatory disorders affecting the joints, connective tissue, lungs, heart, and liver (8053,11477). Symptoms tend to improve over time, however some individuals may still experience symptoms up to 2 years after the onset of EMS and complete resolution of symptoms may not occur (8053,10287).
There is some evidence of an association between L-tryptophan-related EMS and the occurrence of chronic B-cell lymphocytic leukemia (8055).

Ocular/Otic ...Orally, L-tryptophan can cause side effects such as visual blurring (10853).

Pulmonary/Respiratory ...Orally, L-tryptophan has been associated with eosinophilia-myalgia syndrome (EMS), which can include respiratory symptoms such as dyspnea and cough (8053,11477).

General ...Orally and topically, lysine is generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, and dyspepsia.

Gastrointestinal ...Orally, lysine has been reported to cause diarrhea and abdominal pain, including dyspepsia (1114,1115,1116,1118,1120).

Renal ...There is one case report of oral lysine use associated with tubulointerstitial nephritis progressing to chronic renal failure in a 44-year old female (1121).

General ...Orally, methionine is well tolerated when used in amounts commonly found in foods. Intravenously, methionine is generally well tolerated.
Most Common Adverse Effects:
All ROAs: Dizziness, drowsiness, hypotension, irritability, and vomiting. Methionine may also cause headache, increased homocysteine levels, increased urinary calcium excretion, and leukocytosis.
Serious Adverse Effects (Rare):
All ROAs: Cerebral edema, hepatic encephalopathy. In infants, intravenous methionine has been linked to liver toxicity.

Cardiovascular ...Orally or intravenously, methionine can cause hypotension (9339,9340). High-dose methionine (75-100 mg/kg daily) may increase plasma concentrations of homocysteine, which is a risk factor for vascular disease (63112,63114,63115). However, a study of patients with type 2 diabetes and a history of cardiovascular disease (CVD) showed that methionine loading did not increase homocysteine concentrations, and that a cause-effect relationship between increased intake of methionine and endothelial dysfunction has not been clearly established (63110).

Gastrointestinal ...Orally or intravenously, methionine can cause vomiting (9339,9340).

Genitourinary ...Orally or intravenously, methionine may increase urinary calcium excretion (9340,63112,94095).

Hematologic ...Orally or intravenously, methionine may cause leukocytosis when used at a dose of 8-13. 9 grams daily for 4-5 days (9340).

Hepatic ...A single dose of 8 grams of methionine has reportedly caused hepatic encephalopathy in patients with cirrhosis (9340). Long-term use of methionine-containing parenteral nutrition solution has been linked to liver toxicity in infants (9338).

Neurologic/CNS ...Orally or intravenously, methionine can cause dizziness, drowsiness, headache, and irritability (9339,9340,94095).
A case of cerebral edema ultimately leading to death has been reported in a patient receiving methionine 100 mg/kg orally. The post-load plasma concentrations of methionine were substantially higher in this patient than those previously reported in humans receiving this usual oral loading dose, leading the authors to postulate that an overdose of methionine may have been administered erroneously. This can occur when plasma methionine levels rise above 3000 mcmol/L (9339). Another case of progressive cerebral edema associated with high methionine levels and betaine (N,N,N-trimethylglycine) therapy in a patient with cystathionine beta-synthase (CBS) deficiency has been reported (63119). The authors stated that the cerebral edema was most likely precipitated by the betaine therapy, but that the exact mechanism is uncertain.

Oncologic ...Although one case-control study of incident, histologically-confirmed gastric cancer has indicated that a diet rich in methionine, salt, and nitrite is associated with an increased risk of gastric cancer (2409), a large observational study that adjusted for multiple factors, including sodium intake, has found no association between high dietary intake of methionine and gastric cancer (108041).

General ...Orally, L-phenylalanine and D-phenylalanine are generally well tolerated when used in typical doses.
Most Common Adverse Effects:
Orally: Anxiety, constipation, headache, heartburn, insomnia, nausea, and sedation.
Topically: Burning, erythema, and itching.

Cardiovascular ...One patient in a small case series developed extrasystoles after 10 days of treatment with DL-phenylalanine, but this resolved on the 12th day of treatment without discontinuing phenylalanine (68825).

Dermatologic ...Topically, erythema, itching, and burning have been reported in some patients using an undecylenoyl phenylalanine 2% cream for treatment of age spots (92704).

Gastrointestinal ...Orally, constipation, heartburn, and nausea has been reported in some patients taking phenylalanine (2463,68827,68829,68830).

Neurologic/CNS ...Orally, headaches, which are typically transient and do not require treatment or dosage reduction, have been reported during the first 10 days of treatment with L-, D-, and DL-phenylalanine (68795,68825,68827,68829). Transient vertigo has also been reported with D- and DL-phenylalanine (68795).
In patients with Parkinson disease, taking DL-phenylalanine, especially in high doses, interferes with levodopa transport into the brain, causing increased rigidity, tremor, and occurrence of the on-off phenomenon. Akinesia has been reported more rarely (3291,3292,3293,3294,68828). In patients with schizophrenia, taking a single dose of L-phenylalanine 100 mg/kg has been associated with worsening of medication-induced tardive dyskinesia (2457).

Psychiatric ...Orally, L-phenylalanine has been associated with anxiety, insomnia, and, more rarely, hypomania (68827,68829). DL-phenylalanine has been associated with fatigue and sedation (9951).

TAURINE

General ...Orally, taurine is generally well-tolerated when used in typical doses for up to one year.
Most Common Adverse Effects:
Orally: Constipation, diarrhea, and dyspepsia.
Serious Adverse Effects (Rare):
Orally: Hypersensitivity reactions in sensitive individuals. Case reports raise concerns for serious cardiovascular adverse effects, but these reports have involved energy drinks containing taurine and other ingredients. It is unclear if these adverse effects are due to taurine, other ingredients, or the combination.

Cardiovascular ...Changes in heart rate and increased blood pressure have been reported following the co-administration of taurine and caffeine, although the effects of taurine alone are unclear (77088). In healthy individuals, consumption of energy drinks containing taurine increased platelet aggregation and decreased endothelial function (77151,112268,112741). A case of cardiac arrest following strenuous exercise and an excessive intake of energy drinks containing caffeine and taurine has been reported (77136). In another case report, a 28-year-old male without cardiovascular risk factors presented to the hospital with radiating chest pain, shortness of breath, and diaphoresis after excessive intake of an energy drink containing taurine, caffeine, sugar, and glucuronolactone. Electrocardiogram findings confirmed myocardial infarction, and subsequent catheterization confirmed thrombotic occlusion (112741).

Endocrine ...Orally, taurine has been reported to cause hypoglycemia (77153).

Gastrointestinal ...Orally, constipation has been reported following the administration of taurine (77231). Dyspepsia has also been reported after oral taurine use (104165).

Hematologic ...In clinical research, taurine reduced platelet aggregation (77245). A case of massive intravascular hemolysis, presenting with confusion, dark urine, dyspnea, emesis, and fever, has been reported following the administration of a naturopathic vitamin infusion containing taurine, free amino acids, magnesium, and a vitamin B and D complex (77177). However, the effects of taurine alone are unclear.

Immunologic ...A case report describes a hypersensitivity reaction in a female patient with a history of allergies to sulfonamides, sulfites, and various foods, after ingestion of taurine and other sulfur-containing supplements. The amount of taurine in the products ranged from 50-500 mg per dose. The allergic reaction recurred upon rechallenge with taurine 250-300 mg (91514).

Neurologic/CNS ...In a case study, encephalopathy occurred in a body-builder who took approximately 14 grams of taurine in combination with insulin and anabolic steroids. It is not known if this was due to the taurine or the other drugs taken (15536).
Cases of seizures following the consumption of energy drinks containing taurine have been reported (77105,77196). In clinical research, taurine has been reported to cause drowsiness and ataxia in epileptic children (77241).

Psychiatric ...In a case report, a 36-year-old male with adequately controlled bipolar disorder was hospitalized with symptoms of mania after consuming several cans of an energy drink containing taurine, caffeine, glucuronolactone, B vitamins, and other ingredients (Red Bull Energy Drink) over a period of four days (14302). It is unknown if this effect was related to taurine.

Pulmonary/Respiratory ...In human research, an exacerbation of pulmonary symptoms of cystic fibrosis has been associated with taurine supplementation, although this could also be caused by progression of the disease (77231).

Renal ...A case of acute kidney failure has been reported following the concomitant intake of 1 liter of vodka and 3 liters of an energy drink providing taurine 4. 6 grams, caffeine 780 mg, and alcohol 380 grams (77185).

General ...Orally, threonine seems to be well tolerated.

Dermatologic ...Orally, skin rash has been reported in people who have taken threonine (681).

Gastrointestinal ...Orally, some patients can experience minor gastrointestinal upset including diarrhea (12056). Other side effects reported in people who have taken threonine include flatus and constipation (681).

Neurologic/CNS ...Orally, headache has been reported in people who have taken threonine (681).

Pulmonary/Respiratory ...Orally, rhinorrhea has been reported in people who have taken threonine (681).

Other ...Orally, a two-fold increase in serum ammonia levels occurred in one patient following administration of threonine 4 grams daily (681).

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