Brain Select [Discontinued] by Moss Nutrition

POSSIBLY EFFECTIVE

• Age-related cognitive decline. Oral acetyl-L-carnitine may improve age-related cognitive decline. Details: Clinical research shows that taking acetyl-L-carnitine 1500-2000 mg daily for 3 months seems to improve some measures of cognitive function and memory in elderly people with age-related cognitive decline (42,3600,3601).
• Age-related fatigue. Oral acetyl-L-carnitine may improve age-related physical and mental fatigue. Details: One clinical trial shows that taking acetyl-L-carnitine 2 grams twice daily for 180 days reduces physical fatigue by 52% and mental fatigue by 43%, compared with only 4% and 8%, respectively, for elderly patients taking placebo. Fatigue after exercise is also reduced by 51% in those taking acetyl-L-carnitine, compared with only 4% in those taking placebo (58375).
• Alcohol use disorder. Intravenous acetyl-L-carnitine may reduce cravings and other symptoms of withdrawal during alcohol detoxification. It is unclear if oral acetyl-L-carnitine is beneficial for managing withdrawal or complications of alcohol use disorder. Details: Clinical research in adults with alcohol use disorder who are in withdrawal shows that acetyl-L-carnitine 1-3 grams daily, administered as a slow intravenous infusion over 3-4 hours for 10 days, followed by 3 grams daily orally for an additional 80 days, improves cravings, the inability to feel pleasure (anhedonia), and melancholic symptoms and increases the time to the first drink when compared with placebo. However, most symptom improvement appears to occur during the first week, so it is unclear if taking acetyl-L-carnitine 3 grams daily orally for an additional 80 days is beneficial (90766,90767). One small clinical trial in adults with chronic alcohol use disorder and cognitive impairment shows that taking acetyl-L-carnitine 2 grams daily for 90 days seems to improve memory and visuospatial capacity when compared with placebo (1589).
• Alzheimer disease. Oral acetyl-L-carnitine may slow the progression of Alzheimer disease and improve some measures of cognitive function. Details: Clinical research shows that taking acetyl-L-carnitine 1.5-3 grams daily for 3-12 months might slow the rate of Alzheimer disease progression and improve memory, some measures of cognitive function, and behavioral performance. It is more likely to show some effect in those with early-onset Alzheimer disease who are less than 66 years of age and have a faster rate of disease progression and mental decline (1594,1595,1596,1597,1598,1599,9105,10391). It is unclear how acetyl-L-carnitine compares with prescription medications.
• Depression. Oral acetyl-L-carnitine may reduce symptoms of depression, with comparable effects to conventional antidepressants, in patients with dysthymia and depression. It may be most effective in elderly patients and at higher doses. Details: Several clinical trials addressing the use of acetyl-L-carnitine in elderly patients with dysthymia and depression have been conducted (3602,3603,3604). A meta-analysis of these and other studies, all conducted in Europe, shows that taking acetyl-L-carnitine 1-4 grams daily for 3-24 weeks moderately reduces depressive symptoms when compared with placebo, and appears to have similar effects as conventional antidepressants. Acetyl-L-carnitine seems to be most effective when used at higher dosages. Duration of follow-up and baseline symptoms do not appear to influence results (95065).
• Diabetic neuropathy. Oral acetyl-L-carnitine may reduce pain in patients with diabetic neuropathy when taken at doses of at least 2-3 grams daily. It is unclear if oral acetyl-L-carnitine can improve nerve conduction velocity in these patients. Details: Although most clinical research evaluating acetyl-L-carnitine for use in diabetic neuropathy has shown benefit, this evidence is of overall low quality. A meta-analysis shows that taking acetyl-L-carnitine 2-3 grams daily for up to 12 months modestly reduces pain scores by about 15 points on a 100-point visual analog scale, while lower doses of 1.5 grams daily improve pain scores to a similar extent as placebo. Some research included in this analysis shows that acetyl-L-carnitine seems to increase nerve fibers, regenerate nerve fiber clusters, and improve vibratory sensations. In two studies, vibration sensation improved after 12 months when compared with placebo, but numerical data are lacking (102126). Other clinical research shows that taking acetyl-L-carnitine 1000 mg 2-3 times daily decreases pain within 6 months. Acetyl-L-carnitine seems to be most effective for reducing pain in patients with a shorter duration of diabetes and in patients with poorly controlled type 2 diabetes. Some research shows that taking acetyl-L-carnitine 500 mg (Liaoning Haisike Pharmaceutical Co. Ltd.) three times daily for 24 weeks is as effective as methylcobalamin 0.5 mg three times daily for improving electrophysiological parameters and symptoms as measured by the Neuropathy Disability Score (95067,102126). However, research on the use of acetyl-L-carnitine to improve nerve conduction velocity in patients with diabetic neuropathy is conflicting (1593,12743,12753,13007,95067).
• Male infertility. Oral acetyl-L-carnitine, taken in combination with L-carnitine, may increase sperm motility in males with infertility. It is unclear if oral acetyl-L-carnitine alone can improve sperm function or pregnancy outcomes. Details: Although some research disagrees (111861), taking acetyl-L-carnitine in combination with L-carnitine, usually in doses of 1 gram and 2 grams, respectively, daily for 3-6 months seems to increase sperm motility in males with infertility of various etiologies. The evidence related to the effect of this combination on sperm count and morphology is mixed (12352,58182,58194,58469,101560,107394,111459,111890). However, it is unclear if taking L-carnitine increases the odds of pregnancy. One meta-analysis of randomized controlled trials shows that taking these carnitines 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). Taking acetyl-L-carnitine 500 mg and L-carnitine 1 gram twice daily after taking nonsteroidal anti-inflammatory drugs for 2 months seems to increase sperm count and motility in those with abacterial prostatovesiculoepididymitis, an inflammation of the prostate gland, seminal vesicles, and epididymis (9791). Acetyl-L-carnitine has also been evaluated in combination with other ingredients. One study shows that taking acetyl-L-carnitine 50 mg in combination with L-carnitine 150 mg, L-arginine 1660 mg, and Panax ginseng 200 mg daily for 3 months increases sperm motility and sexual satisfaction in those with asthenospermia 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 treatment with prulifloxacin alone in patients with chronic prostatitis due to Chlamydia trachomatis infection (59006). Other small and preliminary Iclinical studies have investigated the effects of a specific combination product providing acetyl-L-carnitine 500 mg twice daily for 6 months, along with 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.

POSSIBLY INEFFECTIVE

• Chemotherapy-induced peripheral neuropathy. The evidence related to the effect of oral acetyl-L-carnitine on symptoms of chemotherapy-induced peripheral neuropathy is mixed. Some research shows that it may actually worsen symptoms. Details: High quality clinical research in females treated with taxane-based therapy for early-stage breast cancer shows that taking acetyl-L-carnitine 1000 mg three times daily for 24 weeks does not improve symptoms of neuropathy when compared with placebo. In fact, acetyl-L-carnitine treatment may actually make symptoms worse in some patients, with worsened symptoms persisting for up to at least 2 years (90758,96938,111882). Also, a small clinical trial in patients with multiple myeloma receiving bortezomib, doxorubicin, and dexamethasone shows that taking acetyl-L-carnitine 1.5 grams daily does not reduce symptoms of peripheral neuropathy when compared with not taking acetyl-L-carnitine (90756). A small clinical trial in patients with ovarian cancer or castration-resistant prostate cancer receiving sagopilone shows that taking acetyl-L-carnitine 1000 mg every three days appears to reduce the more severe symptoms of peripheral neuropathy; however, the overall incidence or duration of peripheral neuropathy is not reduced when compared with placebo (90757). Some research disagrees. One clinical trial in patients with taxoid-related neuropathy shows that taking acetyl-L-carnitine3 grams daily for 8 weeks modestly improves the severity of neuropathy by at last one grade in 51% of patients compared with 24% of those taking placebo. Functional improvement was also modestly improved (111862). Based on the available research, the American Society of Clinical Oncology strongly discourages the use of acetyl-L-carnitine for the prevention of chemotherapy-induced peripheral neuropathy, noting that the harms outweigh the potential benefits (104168).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related testosterone deficiency. Oral acetyl-L-carnitine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One clinical study in older males shows that taking acetyl-L-carnitine 2 grams, in combination with propionyl-L-carnitine 2 grams, daily for 6 months seems to attenuate symptoms of androgen decline. The combination appears to be similar to testosterone for improving sexual dysfunction, depression, and fatigue (12353). It is unclear if these findings are due to acetyl-L-carnitine, propionyl-L-carnitine, or the combination.
• Aging skin. Although there has been interest in using oral acetyl-L-carnitine for aging skin, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Amenorrhea. Although there has been interest in using oral acetyl-L-carnitine for amenorrhea, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease). It is unclear if oral acetyl-L-carnitine is beneficial in patients with ALS. Details: One small clinical trial in patients with ALS shows that taking acetyl-L-carnitine 1000 mg three times daily for 48 weeks, along with riluzole 50 mg twice daily, reduces the number of patients who lose self-sufficiency by about 17%, increases patient survival by a median of 23 months, and improves some measures of physical function when compared with riluzole alone (90755).
• Antiretroviral toxic neuropathy. Small clinical studies suggest that oral acetyl-L-carnitine may modestly improve symptoms in patients with antiretroviral toxic neuropathy. It is unclear if intramuscular or intravenous acetyl-L-carnitine is beneficial in patients with this condition. Details: Small clinical trials show that taking acetyl-L-carnitine 1000-1500 mg twice daily for up to 33 months might relieve symptoms of distal symmetrical polyneuropathy caused by antiretroviral treatment in HIV-positive patients (12745,58342). Also, a small, uncontrolled clinical study shows that intramuscular or intravenous administration of acetyl-L-carnitine 500-1000 mg daily for 3 weeks reduces pain intensity when compared to baseline in some HIV-positive patients receiving antiretroviral therapy (12747). However, another clinical study shows that intramuscular acetyl-L-carnitine 500 mg twice daily for 14 days does not reduce pain when compared with placebo (58342).
• Athletic performance. Although there has been interest in using oral acetyl-L-carnitine for athletic performance, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Attention deficit-hyperactivity disorder (ADHD). Small clinical trials suggest that oral acetyl-L-carnitine is not beneficial in children with ADHD. Details: One small clinical trial in children and adolescents with ADHD shows that taking acetyl-L-carnitine 1-3 grams daily, based on body weight, in two divided doses along with methylphenidate 20-30 mg daily for 3 weeks does not reduce symptoms of ADHD when compared with methylphenidate alone (90754). Based on this and another small trial, Guidelines from The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce state that acetyl-L-carnitine in doses of 1-3 grams daily is not recommended for adjunctive or monotherapy use for ADHD in children (110318).
• Bell palsy. Although there has been interest in using oral acetyl-L-carnitine for Bell palsy, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Bipolar disorder. Oral acetyl-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 type I or type II bipolar disorder shows that taking acetyl-L-carnitine 1000 mg plus alpha-lipoic acid 600 mg up to three times daily for 12 weeks does not improve depression when compared with placebo (90441).
• Cancer-related fatigue. Although there has been interest in using oral acetyl-L-carnitine for cancer-related fatigue, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Carpal tunnel syndrome. It is unclear if oral acetyl-L-carnitine is beneficial in patients undergoing surgery for carpal tunnel syndrome. Details: A small clinical study in adults undergoing carpal tunnel release surgery shows that taking acetyl-L-carnitine 3000 mg daily for 2 months postoperatively does not improve nerve regeneration or functional recovery when compared with placebo (100349). However, this study may have been inadequately powered to detect a difference between groups. Acetyl-L-carnitine has also been investigated in combination with other ingredients. In patients with mild to moderate symptoms awaiting carpal tunnel release, preliminary clinical research shows that taking acetyl-L-carnitine as part of a multi-ingredient formulation for 60 days reduces pain by 31%, but does not improve function, when compared with no treatment. The formulation provided a total of 600 mg twice daily of acetyl-L-carnitine with alpha-lipoic acid, phosphatidylserine, curcumin, thiamine, riboflavin, and vitamins C, E, B6, and B12 (111702).
• Cataracts. Although there has been interest in using oral acetyl-L-carnitine for cataracts, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Chronic fatigue syndrome (CFS). It is unclear if oral acetyl-L-carnitine is beneficial in patients with CFS. Details: Preliminary clinical research in patients with CFS shows that taking acetyl-L-carnitine 2 grams daily for 6 months improves general fatigue in up to 59% of patients when compared with baseline. The combination of acetyl-L-carnitine and propionyl-L-carnitine appears to be less effective than either supplement alone, with only 37% of patients taking this combination achieving improvement when compared with baseline (11788).
• Diabetes. It is unclear if oral acetyl-L-carnitine improves glycemic control in people with type 2 diabetes. Details: Clinical research in patients with type 2 diabetes, hypertension, and dyslipidemia shows that taking acetyl-L-carnitine 1 gram twice daily for 6 months does not improve blood glucose levels, glycated hemoglobin, fasting insulin levels, insulin resistance, or glucose disposal rate when compared with placebo. Most patients were already taking one or more antidiabetes drug, as well as medication for hypertension and dyslipidemia (96937). It is unclear if acetyl-L-carnitine improves glycemic profile in patients with uncontrolled diabetes.
• Down syndrome. Although there has been interest in using oral acetyl-L-carnitine for Down syndrome, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Dyslipidemia. It is unclear if oral acetyl-L-carnitine reduces lipid levels in adults with dyslipidemia. Details: Clinical research in patients with dyslipidemia, type 2 diabetes, and hypertension shows that taking acetyl-L-carnitine 1 gram twice daily for 6 months does not improve cholesterol, triglycerides, or lipoprotein(a) levels when compared with placebo. All patients were taking statins prior to treatment with acetyl-L-carnitine, and most were receiving medication for hypertension and diabetes (96937). It is unclear if acetyl-L-carnitine is beneficial in patients not taking statins.
• Fibromyalgia. It is unclear if oral and/or intramuscular acetyl-L-carnitine can improve symptoms of fibromyalgia. Details: One clinical study in patients with fibromyalgia shows that taking acetyl-L-carnitine 1000 mg daily orally plus acetyl-L-carnitine 500 mg daily intramuscularly for 2 weeks, followed by acetyl-L-carnitine 1500 mg daily orally for 8 weeks, reduces muscle pain and improves mood, general health, and quality of life when compared with placebo (90768). A smaller clinical study in patients with fibromyalgia shows that taking acetyl-L-carnitine 500 mg three times daily for 12 weeks improves quality of life (physical) scores and symptoms of depression, but not pain, anxiety, or quality of life (mental) scores when compared with baseline (90761). The validity of these findings is limited by the lack of a comparator group. Acetyl-L-carnitine has also been investigated in combination with other ingredients. Clinical research shows that taking acetyl-L-carnitine 500 mg and palmitoylethanolamide (PEA) 600 mg twice daily for 12 weeks increases the proportion of patients with at least a 30% reduction in pain by 86% when compared with not taking this combination. There was also a modest improvement in the overall assessment of status. All patients were on stable treatment with duloxetine and pregabalin for 3 months prior to the initiation of acetyl-L-carnitine and PEA, and this treatment continued throughout the study (111901).
• Fragile X syndrome. Small clinical studies suggest that oral acetyl-L-carnitine is not beneficial in children with fragile X syndrome. Details: Two small clinical studies in children with fragile X syndrome shows that acetyl-L-carnitine 20-50 mg/kg daily for one year does not improve intellectual function when compared with placebo. Also, while it may reduce hyperactive behavior in these patients based on parent assessment, it does not appear to reduce hyperactive behavior based on teacher assessment (9956,93063).
• Frailty. It is unclear if oral acetyl-L-carnitine prevents frailty. Details: Clinical research in pre-frail older adults shows that taking acetyl-L-carnitine 1.5 grams twice daily for 3 months modestly improves cognition and the distance walked in 6 minutes when compared with taking placebo (111889). It is unclear whether taking acetyl-L-carnitine is beneficial for frailty treatment or prevention.
• Hepatic encephalopathy. Small clinical studies suggest that oral acetyl-L-carnitine may not improve quality of life or fatigue in patients with hepatic encephalopathy due to cirrhosis. Details: The benefits of acetyl-L-carnitine in the management of hepatic encephalopathy due to cirrhosis are unclear (58922,58949,59002,90759). A meta-analysis of the available clinical research shows that taking acetyl-L-carnitine 2 grams twice daily for 90 days does not improve quality of life or fatigue in this population when compared with placebo. However, major clinical outcomes, such as all-cause mortality, days of hospitalization, and serious adverse events, have not been evaluated. Additionally, the validity of these findings is limited by the small size, high risk for bias, and heterogeneity of the included studies (100350).
• Hypertension. It is unclear if oral acetyl-L-carnitine lowers blood pressure in adults with hypertension. Details: Clinical research in patients with hypertension, type 2 diabetes, and dyslipidemia shows that taking acetyl-L-carnitine 1 gram twice daily for 6 months does not improve systolic or diastolic blood pressure when compared with placebo. Most patients were already being treated with antihypertensive drugs prior to treatment with acetyl-L-carnitine, in addition to medications for dyslipidemia and diabetes (96937). It is unclear if acetyl-L-carnitine reduces blood pressure in patients with uncontrolled hypertension.
• Infertility. Although there has been interest in using oral acetyl-L-carnitine for infertility in females, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Lyme disease. Although there has been interest in using oral acetyl-L-carnitine for Lyme disease, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Multiple sclerosis-related fatigue. It is unclear if oral acetyl-L-carnitine is beneficial in patients with multiple sclerosis-related fatigue. Details: One small clinical study in patients with multiple sclerosis shows that taking acetyl-L-carnitine 1 gram twice daily for one month reduces fatigue by approximately 25% when compared with placebo (90760).
• Obesity. Although there has been interest in using oral acetyl-L-carnitine for obesity, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Peripheral neuropathy. Although there has been interest in using oral acetyl-L-carnitine for peripheral neuropathy, there is insufficient reliable information about the clinical effects of acetyl-L-carnitine for this purpose.
• Peyronie disease. A small clinical study suggests that oral acetyl-L-carnitine may modestly improve symptoms of Peyronie disease. Details: One small clinical trial in patients with acute and early chronic Peyronie disease shows that taking acetyl-L-carnitine 1 gram twice daily for 3 months reduces pain and slows disease progression when compared with tamoxifen 20 mg twice daily (10076).
• Polycystic ovary syndrome (PCOS). It is unclear if acetyl-L-carnitine is beneficial in patients with PCOS. Details: A clinical study in patients with PCOS shows that taking acetyl-L-carnitine 1.5 grams, in combination with metformin and pioglitazone, twice daily for 12 weeks improves menstrual irregularity and insulin resistance when compared with baseline. The lack of statistical comparison to placebo, as well as the combined use with metformin and pioglitazone, limits the validity of these findings (107396).
• Schizophrenia. It is unclear if oral acetyl-L-carnitine is beneficial in patients with schizophrenia. Details: A very small, open-label clinical study in patients with schizophrenia who partially responded to clozapine therapy shows that taking acetyl-L-carnitine 1 gram daily, in combination with clozapine 300-600 mg daily, for 12 weeks reduces positive symptoms of schizophrenia, but not cognitive function or other clinical symptoms, when compared with baseline (95063). The validity of these findings is limited by the lack of a comparator group.
• Sciatica. It is unclear if oral acetyl-L-carnitine is beneficial in patients with sciatica. Details: One small clinical trial in patients with sciatica secondary to a herniated disc shows that taking acetyl-L-carnitine (Nicetile, SigmaTau Ind. Farm. Riunite SpA,) 1180 mg daily for 60 days decreases the use of analgesics when compared with baseline. However, acetyl-L-carnitine appears to be less effective than alpha-lipoic acid (Byodiniral 300 QR, MDM SpA,) 600 mg daily for reducing lower limb pain and the use of analgesics (21671).
• Stroke. It is unclear if oral acetyl-L-carnitine is beneficial following a stroke. Details: Clinical research in patients with an acute ischemic stroke given routine care shows that oral or nasogastric acetyl-L-carnitine 1 gram three times daily for 3 days modestly improves stroke impairment and overall function 3 months after the stroke when compared with taking placebo. The proportion of patients taking acetyl-L-carnitine with no symptoms or obvious disability at 3 months was 53%, compared with 29% of patients taking placebo. The patients in this study were not candidates of reperfusion therapy and initiated acetyl-L-carnitine within 24 hours of the stroke (111894).
• Toxin-induced liver damage. Oral acetyl-L-carnitine has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients being treated with anti-tuberculosis drugs shows that taking acetyl-L-carnitine 250 mg, along with coenzyme Q10 and alpha-lipoic acid, twice daily for 2 weeks reduces the risk of drug-induced liver injury by 73% when compared with placebo (107445). It is unclear if these findings are due to acetyl-L-carnitine, other ingredients, or the combination. More evidence is needed to rate acetyl-L-carnitine for these uses.

(Read more about ACETYL-L-CARNITINE)

LIKELY INEFFECTIVE

• Alzheimer disease. Oral deanol does not appear to improve memory in individuals with Alzheimer disease. Details: Two very small clinical trials in patients with Alzheimer disease show that taking deanol, titrated up to a dose of 600 mg three times daily, for 4-5 weeks does not seem to improve memory or other cognitive functions when compared with placebo (1680,1681).
• Tardive dyskinesia. Oral deanol does not improve symptoms of tardive dyskinesia. Details: Meta-analyses and individual clinical studies show that taking deanol 1-2 grams daily for up to 1 month does not improve symptoms of tardive dyskinesia when compared with baseline or placebo (1672,1673,1674,1675,1676,1803,1804).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging. Although there has been interest in using oral deanol to prevent aging and extend life span, there is insufficient reliable information about the clinical effects of deanol for this purpose.
• Aging skin. Although there has been interest in using topical deanol for aging skin, there is insufficient reliable information about the clinical effects of deanol for this purpose.
• Athletic performance. Oral deanol has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in healthy males shows that taking deanol in combination with ginseng, vitamins, and minerals for 6 weeks improves exercise performance by increasing total work load and maximal oxygen consumption during exercise (1671). It is unclear if these findings are due to deanol, other ingredients, or the combination.
• Attention deficit-hyperactivity disorder (ADHD). It is unclear if oral deanol is beneficial in children with ADHD. Details: Clinical research on the use of deanol in children with ADHD-like symptoms is mixed (1669,1677,1679,92702). One moderate sized clinical study in children with behavioral and learning disorders, most of whom also had hyperactivity, shows that taking deanol 500 mg daily for 3 months significantly improves performance on various psychometric tests when compared with placebo. The improvements seen with deanol were similar to those reported with methylphenidate 40 mg daily (1679). Another small study in children 6-12 years of age with behavior problems consistent with ADHD shows that taking deanol 300-500 mg daily for 12 weeks improves some measures of performance when compared with placebo (92702). However, other research shows that deanol does not improve ADHD symptoms in children (1669,1677). The children evaluated in each of these studies were not diagnosed with ADHD using current diagnostic guidelines, limiting the applicability of these results in clinical practice.
• Autism spectrum disorder. Although there has been interest in using oral deanol for autism spectrum disorder, there is insufficient reliable information about the clinical effects of deanol for this purpose.
• Cognitive function. Although there has been interest in using oral deanol to improve cognitive function, there is insufficient reliable information about the clinical effects of deanol for this purpose. More evidence is needed to rate deanol for these uses.

(Read more about DEANOL)

POSSIBLY EFFECTIVE

• Alzheimer disease. Oral huperzine A seems to improve memory, cognitive function, and behavior in patients with this condition. Details: Meta-analyses of small clinical studies in patients with Alzheimer disease show that, overall, huperzine A 200-800 mcg in 2-3 divided doses daily for 8-36 weeks improves cognitive function as measured on some scales, but not others, when compared with placebo (55674,93482). Improvement in cognitive function was observed consistently when measured using the Mini-Mental State Examination (MMSE) (55674,93482,93483,101469). However, results are inconsistent with other scales, such as the Alzheimer Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), the Hasegawa Dementia Scale (HDS), and the Wechsler Memory Scale (WMS) (55674,93482). Meta-analyses also show that huperzine A improves overall behavior and performance of daily living activities when compared with placebo (55674,93482). Most research has been conducted in China, where huperzine A is an approved drug for this condition. Only one clinical trial has been conducted in the United States. This study was conducted in patients with probable mild to moderate Alzheimer disease and shows that taking huperzine A 200 mcg twice daily for at least 16 weeks does not improve cognition based on the ADAS-Cog when compared with placebo. However, this dose results in modest benefit when cognition is measured using the MMSE, and a higher dose of 400 mcg twice daily shows modest benefit when measured on both the ADAS-Cog and MMSE (93479). Long-term, large-scale clinical trials in diverse geographic locations are necessary to confirm these findings and determine which dose of huperzine A, if any, is beneficial.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Athletic performance. It is unclear if oral huperzine A is beneficial for improving athletic performance. Details: One very small, double-blind randomized crossover study in physically active adults shows that taking huperzine A 200 mcg as a single dose 30-45 minutes prior to exercise does not affect athletic performance, neuromuscular performance, or cognitive function when compared with placebo (107470). Due to the single-dose nature of this study, the effects of continued administration of huperzine A on athletic performance are unclear.
• Cocaine dependence. It is unclear if oral huperzine A is beneficial in patients with cocaine use disorder. Details: A very small clinical study in adults with cocaine use disorder shows that taking huperzine A in gradually increasing doses over 9 days, up to a dose of 200 or 400 mcg twice daily, might attenuate the stimulation and anxiety effects of an intravenous cocaine infusion when compared with placebo (93484). It is unclear if huperzine A can attenuate cravings and cocaine use in these individuals.
• Cognitive impairment. Although there is interest in using oral huperzine A for mild cognitive impairment, there is insufficient reliable information about the clinical effects of huperzine A for this condition.
• Depression. It is unclear if oral huperzine A is beneficial in patients with major depressive disorder. Details: A meta-analysis of three small, low-quality clinical studies in patients with major depressive disorder shows that taking huperzine A 100-300 mg daily in combination with antidepressants for 6-8 weeks does not further improve depressive symptoms when compared with antidepressants alone. However, huperzine A might improve cognitive functioning, based on the Wisconsin Card Sorting Test and the Wechsler Memory Scale-Revised (WMS-R) (93485). All available research has been conducted in China, so it is unclear if these findings are generalizable to other geographic locations.
• Memory. It is unclear if oral huperzine A is beneficial for improving memory in healthy adolescents. Details: A small clinical trial in Chinese adolescents around 15 years of age who complain of poor memory shows that taking huperzine A 100 mcg daily for 4 weeks improves memory quotient scores when compared with placebo (4626).
• Myasthenia gravis. It is unclear if intramuscular huperzine A is beneficial in patients with myasthenia gravis. Details: A small, open-label clinical trial in stabilized patients with myasthenia gravis shows that giving huperzine A 400 mcg intramuscularly for 10 days maintains muscle strength similarly to patients treated with intramuscular neostigmine alternating with intramuscular huperzine A. Huperzine A was reported to have a 7-hour duration of effect, compared to only 4 hours with neostigmine (3561).
• Schizophrenia. Small clinical studies suggest that oral huperzine A may modestly improve symptoms of schizophrenia in adults. Details: A meta-analysis of small, low-quality clinical trials in hospitalized patients with schizophrenia shows that taking huperzine A 150-400 mcg daily for 8-24 weeks as an adjunct to antipsychotic medications improves memory, intelligence, and positive, but not negative, psychiatric symptoms when compared with antipsychotic medications alone (93478). Limited research also suggests that huperzine A might improve outcomes in patients with resistant schizophrenia and cognitive impairment. A small, open-label clinical study in patients with treatment-resistant schizophrenia and cognitive impairment shows that adding huperzine A 300 mcg daily for 12 weeks to treatment with antipsychotics improves negative symptoms of schizophrenia by 32% and memory by 15% when compared to baseline (55665). The validity of this finding is limited by the lack of a comparator group. Furthermore, all available research has been conducted in China, so it is unclear if these findings are generalizable to other geographic locations.
• Vascular dementia. Small clinical studies suggest that oral huperzine A may modestly improve symptoms of vascular dementia in adults. Details: A meta-analysis of two small clinical trials in patients with vascular dementia shows that taking huperzine A 200-300 mcg daily for 12-24 weeks modestly improves cognitive function and activities of daily living when compared with control (93483). The validity of this meta-analysis is limited by small study size and publication bias. More evidence is needed to rate huperzine A for these uses.

(Read more about HUPERZINE A)

LIKELY EFFECTIVE

• Pellagra. Oral niacinamide is approved for the treatment of pellagra and niacin deficiency. Details: Niacinamide is FDA-approved for the prevention and treatment of niacin deficiency and pellagra. Niacinamide is sometimes preferred over niacin for this indication because it lacks the vasodilating and flushing effects of niacin (15,6243).

POSSIBLY EFFECTIVE

• Acne. Topical niacinamide seems to improve acne symptoms in some patients. Oral niacinamide has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One clinical study shows that applying niacinamide 4% gel twice daily for 8 weeks is as effective as clindamycin 1% gel for reducing the number and severity of acne lesions. The niacinamide gel appears to be more effective in patients with oily skin than those with non-oily skin (93360). Other preliminary clinical research in adults with mild to moderate acne vulgaris shows that applying niacinamide 5% cream twice daily, 10 minutes after applying benzoyl peroxide 2.5% gel, for 12 weeks reduces the number of acne lesions, but not erythema or inflammation, when compared with benzoyl peroxide alone (107711). Niacinamide has also been studied in combination with other ingredients. In preliminary clinical research, oral niacinamide has been reported to improve acne when used in combination with zinc, copper, and folic acid (Nicomide) (25557), or in combination with azelaic acid, zinc, pyridoxine, copper, and folic acid (NicAzel, Elorac Inc.) (90800). In a small observational study, topical niacinamide 4% combined with gallic acid 1% and lauric acid 1% was associated with some improvement in acne (104931). It is unclear if the effects in these studies are due to niacinamide, other ingredients, or the combinations.
• Diabetes. Oral niacinamide does not seem to prevent the onset of type 1 diabetes, although it might slow its progression. Details: Although some older research has suggested that taking high-dose niacinamide can reduce the risk of type 1 diabetes in high-risk children (4874), results from higher quality, more rigorous clinical trials show that taking niacinamide up to 3 grams daily for 5 years does not prevent the onset of type 1 diabetes in first-degree relatives of patients with type 1 diabetes (4875,25553,25554). However, taking niacinamide 1.2 grams/m2 daily for 5 years may prevent the loss of beta-cell function in these patients (25555). Also, there is evidence showing that niacinamide can preserve residual beta-cell function in patients with newly diagnosed type 1 diabetes (4877,4878,4879,4880,25556). Clinical trials, including one placebo-controlled trial and one vitamin E-comparison study, show niacinamide can prolong the "honeymoon period" in those newly diagnosed with type 1 diabetes, when the pancreas is still capable of producing some insulin (4877,4878,4879,4880,25556). However, some scientists have raised concerns about potential induction of insulin resistance with short-term use of niacinamide 2 grams daily for 2 weeks (4881). Niacinamide has also been evaluated in adults with type 2 diabetes. A small clinical study in lean patients with type 2 diabetes who failed sulfonylurea therapy shows that taking niacinamide 500 mg three times daily for 6 months in addition to continuing insulin or a sulfonylurea increases C-peptide release and improves insulin secretion when compared with insulin alone (4882).
• Hyperphosphatemia. Adding oral niacinamide to standard treatment with phosphate binders further lowers blood levels of phosphorus in patients on hemodialysis. Details: A meta-analysis of nine small clinical trials in patients on hemodialysis with hyperphosphatemia who are using a phosphate binder shows that taking niacinamide 250-1500 mg daily for 2-6 months lowers serum phosphorus and parathyroid hormone levels when compared with placebo (98940) Another meta-analysis of two small clinical trials in the same patient population also shows that taking niacinamide, titrated from 500 mg to 1500 mg daily over 8 weeks, reduces serum phosphorus levels by about 0.9 mg/dL when compared with placebo (94188). Other clinical research in this population shows that taking modified-release niacinamide 250-1500 mg orally daily for 12-24 weeks also lowers serum phosphate and parathyroid levels when compared with placebo. However, these effects were not maintained at 40-52 weeks follow-up (107709,110499). In addition, this product was not compared with immediate-release niacinamide. Niacinamide has also been studied in place of phosphate binders. One small clinical study in patients on hemodialysis with hyperphosphatemia shows that taking niacinamide 500-1750 mg daily for 12 weeks, beginning 2 weeks after discontinuation of phosphate binders, decreases serum phosphorus levels by 1.5 mg/dL and intact parathyroid hormone levels by 50 pg/mL, without affecting calcium levels, when compared to baseline (25561).The validity of these findings is limited due to the lack of a control group.
• Nonmelanoma skin cancer. Oral niacinamide might reduce the rate of nonmelanoma skin cancer development. Details: One clinical study in patients with a history of nonmelanoma skin cancers shows that taking niacinamide 500 mg orally twice daily for 12 months reduces the rate of new nonmelanoma skin cancers at 12 months by 23% and the number of actinic keratoses by 13% when compared with placebo (93362). Other clinical research shows that taking niacinamide (Nature's Own, Virginia) 500 mg orally once or twice daily for 4 months reduces the total number of actinic keratoses by up to 35% and decreases the odds of developing at least one nonmelanoma skin cancer by 86% when compared with placebo in patients with at least four actinic keratoses (93365). However, some conflicting research exists. One small clinical study in adults with actinic keratoses shows that taking niacinamide 500 mg twice daily for 120 days does not reduce the number of actinic keratoses when compared with control. However, the validity of this study is limited by the short study duration (107714). A meta-analysis of many small clinical trials shows that using niacinamide, up to 2000 mg orally or 4% topically, daily for 1 month to 5 years lowers the risk of skin cancer, including basal cell carcinoma and cutaneous squamous cell carcinoma by 50% when compared with control. Using niacinamide did not reduce the risk of actinic keratoses. However, the validity of this study is limited by inclusion of populations with different cancer risks and high heterogeneity (110497).
• Osteoarthritis. Oral high-dose niacinamide might be beneficial for improving osteoarthritis symptoms. Details: Clinical research in patients with osteoarthritis shows that taking niacinamide 3 grams daily in six divided doses for 12 weeks improves joint flexibility, reduces inflammation, and modestly decreases use of nonsteroidal anti-inflammatory drugs (NSAIDs) when compared with placebo (4883).

POSSIBLY INEFFECTIVE

• Brain tumor. Adding high-dose oral niacinamide to chemotherapy does not seem to improve survival in patients with brain tumors. Details: Preliminary clinical research in patients with surgically resected brain tumors shows that treatment with radiotherapy, niacinamide, and carbogen does not improve survival when compared with radiotherapy alone or radiotherapy plus carbogen (11695,11696).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. Although there is interest in using oral niacinamide for age-related cognitive decline, there is insufficient reliable information about the clinical effects of niacinamide for this purpose.
• Age-related macular degeneration (AMD). Oral niacinamide has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical study in patients with early-stage age-related maculopathy shows that taking a combination of niacinamide 18 mg, vitamin E 20 mg, and lutein 15 mg daily for nearly a year improves retinal function when compared with no treatment (60134). It is unclear if this effect is due to niacinamide, other ingredients, or the combination.
• Aging skin. It is unclear if topical niacinamide improves symptoms of aging skin. Details: A small study in females with signs of facial photo-aging shows that applying niacinamide 5% cream to half of the face twice daily for 12 weeks improves blotchiness, the appearance of wrinkles, skin elasticity, and skin pigmentation when compared with applying placebo cream to the other half of the face (25551).
• Atopic dermatitis (eczema). It is unclear if topical niacinamide improves eczema symptoms. Details: A small clinical study in patients with atopic dermatitis and dry skin shows that applying niacinamide 2% cream twice daily for 8 weeks decreases skin water loss and improves skin hydration when compared with using a white petrolatum moisturizer (25560).
• Attention deficit-hyperactivity disorder (ADHD). Oral niacinamide has only been evaluated in combination with other vitamins; its effect when used alone is unclear. Details: A small clinical study in children with ADHD shows that taking a maximum of niacinamide 3 grams, ascorbic acid 3 grams, calcium pantothenate 1.2 grams, and pyridoxine 600 mg daily for 3 months seems to improve behavior in 29% of participants when compared with baseline (9957). The validity of this finding is limited by the lack of a comparator group.
• Bladder cancer. Oral niacinamide has only been evaluated in combination with carbogen for improving survival in advanced bladder cancer; its effect when used alone is unclear. Details: A phase II clinical study in patients with locally advanced bladder cancer shows that adding inhaled carbogen and oral niacinamide 40-60 mg/kg about 2 hours before radiotherapy shows a trend to improved survival at 3 years when compared with inhaled carbogen and radiotherapy (25558), and a larger phase III study shows that carbogen and oral niacinamide improves 3-year survival by about 13% when compared with radiotherapy alone (93366). An observational follow-up of the phase III study found a trend to increased survival at 5 years in the carbogen and niacinamide group when compared with radiotherapy alone. And in a subgroup of patients with tumor necrosis, the 5-year survival was significantly greater with carbogen and niacinamide when compared with radiotherapy alone (93356). It is unclear if these effects are due to niacinamide, carbogen, or the combination.
• Child growth. It is unclear if oral niacinamide improves child growth. Details: Preliminary clinical research in children in rural Tanzania shows that supplementing niacinamide orally from birth to 18 months of age does not improve length-for-age, weight-for-age, or head circumference when compared with control. Niacinamide was initially supplemented to breast-feeding mothers, 250 mg daily, until 6 months of age, followed by 100 mg daily taken by the child until 18 months of age (107713).
• Coronavirus disease 2019 (COVID-19). It is unclear if oral niacinamide is beneficial for COVID-19. Details: Observational research in adults with acute kidney injury secondary to coronavirus disease-19 infection has found that taking niacinamide 1000 mg orally daily for 7 days is associated with a 55% lower risk of mortality when compared with control. However, taking niacinamide was not associated with a lower risk of renal replacement therapy (110500).
• Cutaneous lupus erythematosus (CLE). It is unclear if topical niacinamide is beneficial for CLE. Details: Preliminary clinical research in adults with discoid lupus erythematosus, a type of CLE, shows that applying topical niacinamide 2% to 4% twice daily for 12 weeks modestly improves lesion scores, but not quality of life scores, when compared with placebo. However, the study may have been inadequately powered to detect a difference between groups (110498).
• Depression. Although there is interest in using oral niacinamide for depression, there is insufficient reliable information about the clinical effects of niacinamide for this condition.
• Diabetic neuropathy. Oral niacinamide has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with diabetic polyneuropathy shows that taking a specific combination product (Cytoflavin, Polysan) containing niacinamide, inosine, riboflavin, and succinate daily for 12 weeks improves symptom scores, including paresthesia and numbness scores, when compared with placebo. The therapy was administered intravenously, containing niacinamide 20 mg, inosine 40 mg, riboflavin 4 mg, and succinate 200 mg, for 10 days followed by orally, containing niacinamide 50 mg, inosine 100 mg, riboflavin 10 mg and succinate 600 mg, for the remainder of the study (110503).
• Erythema. Topical niacinamide has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: There is interest in using niacinamide to reduce the side effects of topical tretinoin, including erythema. A small preliminary clinical study in patients using isotretinoin for acne shows that applying a specific cream (Sebiaclear Hydra, SVr Laboratoire Dermatologique) containing niacinamide 5% and omega-ceramides 8% twice daily for 6 months reduces isotretinoin-induced erythema, dryness, and itching of the skin when compared with a glycerin placebo (98938). It is not clear if this effect is due to niacinamide, omega-ceramides, or the combination.
• Head and neck cancer. Oral niacinamide has only been evaluated in combination with carbogen for improving survival in laryngeal cancer; its effect when used alone is unclear. Details: A phase III clinical trial in patients with laryngeal cancer shows that treatment with accelerated radiotherapy plus carbogen and niacinamide 60 mg/kg taken orally 1-1.5 hours prior to each fraction of radiation improves local tumor control, but does not improve overall survival or 5-year disease-free survival, when compared with accelerated radiotherapy alone. In a subgroup of patients with hypoxic tumors, anemia, or high expression of epidermal growth factor receptor, receiving niacinamide and carbogen seems to improve both survival and tumor control when compared with radiotherapy alone (93358,93359,93363).
• Melasma. It is unclear if topical niacinamide improves uneven skin pigmentation. Details: A small clinical study in Japanese females with uneven facial hyperpigmentation shows that applying niacinamide 5% moisturizer to the face twice daily reduces hyperpigmentation and increases skin lightness after 4 weeks when compared with placebo moisturizer. However, further improvements are not observed after another 4 weeks of treatment (25552). Another small clinical study in Korean females with uneven facial hyperpigmentation shows that applying a moisturizer containing niacinamide 2% plus tranexamic acid 2% (Regederm RX White Project, Aestura) twice daily for 8 weeks reduces skin pigmentation by about 9% when compared with a placebo cream (93361).
• Non-Hodgkin lymphoma. It is unclear if adding oral niacinamide to chemotherapy reduces relapses of refractory lymphoma. Details: One small clinical study in patients with relapsed or refractory lymphoma shows that 24% of patients achieve complete or partial remission and 57% achieve disease stabilization when compared with baseline, following treatment with vorinostat 400 mg daily and niacinamide titrated from 20 mg/kg to 100 mg/kg over the first 14 days of a 21-day cycle for up to 18 cycles (93355). It is unclear how these outcomes compare to using vorinostat alone, or to other control treatments.
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral niacinamide is beneficial for NAFLD. Details: Preliminary clinical research in adults with NAFLD and diabetes shows that taking a specific niacinamide product (Nature's Life) 1000 mg orally daily for 12 weeks does not improve liver function tests, liver steatosis, or liver fibrosis when compared with no intervention. However, some quality of life domain scores were moderately improved. However, the study may have been inadequately powered to detect a difference between groups (110502).
• Premenstrual syndrome (PMS). Although there is interest in using oral niacinamide for PMS, there is insufficient reliable information about the clinical effects of niacinamide for this condition.
• Pruritus. It is unclear if oral niacinamide reduces pruritus in patients with kidney failure. Details: A small clinical study in patients with pruritus due to kidney failure shows that taking niacinamide sodium 500 mg twice daily for 4 weeks does not reduce pruritus severity when compared with placebo (93364). This study is limited due to small size and short study duration.
• Psoriasis. It is unclear if oral niacinamide is beneficial for psoriasis. Details: Preliminary clinical research in adults with mild to moderate psoriasis shows that applying niacinamide 4% cream topically twice daily for 12 weeks improves psoriasis scores by 31% when compared with baseline. The validity of these results is limited by the lack of a comparator group (110501).
• Rosacea. Oral niacinamide has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that 71% of adult and adolescent patients with rosacea who take a combination product (Nicomide) containing niacinamide 750 mg, zinc 25 mg, copper 1.5 mg, and folic acid 500 mcg once or twice daily report improvement in appearance after 4 weeks when compared to baseline (25557). The validity of these findings is limited by the lack of a control group.
• Schizophrenia. Although there is interest in using oral niacinamide for schizophrenia, there is insufficient reliable information about the clinical effects of niacinamide for this condition.
• Seborrheic dermatitis. It is unclear if topical niacinamide is beneficial for reducing seborrheic dermatitis symptoms. Details: One small clinical study in patients with seborrheic dermatitis shows that applying niacinamide 4% cream once daily for 12 weeks reduces the severity of symptoms such as redness and scaling by 75%, compared with a 35% reduction when using a placebo cream (93357). More evidence is needed to rate niacinamide for these uses.

(Read more about NIACINAMIDE)

POSSIBLY EFFECTIVE

• Age-related cognitive decline. Oral bovine cortex-derived phosphatidylserine seems to improve attention and memory in patients with age-related cognitive decline. It is unclear if plant-derived phosphatidylserine is beneficial or whether phosphatidylserine is beneficial for preventing cognitive decline. Details: Clinical studies in people with age-related cognitive decline show that phosphatidylserine improves attention, arousal, verbal fluency, and memory (2440,2441,7119,7120,15539). Bovine- and plant-sourced phosphatidylserine 100 mg three times daily for up to 6 months has been used in these studies (2440,2441,15539). Most clinical studies have used phosphatidylserine derived from bovine cortex. However, most supplements now use soy- or cabbage-derived phosphatidylserine. There is some preliminary evidence that plant-derived phosphatidylserine also improves memory in people with age-associated memory impairment (15539). Also, clinical research in elderly females with complaints of memory loss shows that taking 1-3 capsules of a specific product (Vayacog, Enzymotec Ltd.) containing soybean-derived phosphatidylserine 100 mg/capsule, enriched with docosahexaenoic acid (DHA) 19.5 mg/capsule and eicosapentaenoic acid (EPA) 6.5 mg/capsule, daily for 15 weeks modestly improves immediate memory and sustained attention when compared with placebo (66055,90711). A post-hoc analysis of the results from this study suggests that cognitive improvements are greatest in patients with relatively good cognitive performance at baseline (66055). There is also interest in using phosphatidylserine to prevent age-related cognitive decline. In 2003, the US Food and Drug Administration (FDA) determined that it would allow a qualified health claim stating that consuming phosphatidylserine may reduce the risk of developing age-related cognitive decline. However, the FDA has determined that there is very little scientific evidence supporting this claim (102363).
• Alzheimer disease. Oral bovine cortex-derived phosphatidylserine seems to improve cognitive function and behavior in patients with Alzheimer disease when used for up to 12 weeks, although benefits may disappear after 16 weeks. It is unclear if plant-derived phosphatidylserine is beneficial. Details: Taking phosphatidylserine orally can improve cognitive function and global improvement rating scales and improve behavioral rating scales over 6-12 weeks of treatment (2255,2437,2438,2439,7114,7118). Bovine-sourced phosphatidylserine 300-400 mg in divided doses daily for up to 16 weeks has been used (2255,2437,2438,2439). Phosphatidylserine seems to be most effective in patients with less severe symptoms (2437,2439). Phosphatidylserine might lose its effectiveness with extended use. After 16 weeks of treatment, progression of Alzheimer disease seems to overcome any benefit of phosphatidylserine (2255). Most clinical studies have used phosphatidylserine derived from bovine cortex. However, most supplements now use soy- or cabbage-derived phosphatidylserine. Clinical studies have not yet evaluated phosphatidylserine from soy or other sources. It is not known if phosphatidylserine from these sources is as effective as bovine-derived products.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Athletic performance. It is unclear if oral phosphatidylserine is beneficial for athletic performance. Details: One small clinical trial in golfers shows that taking nutritional bars containing phosphatidylserine 200 mg daily for 6 weeks improves the number of good ball flights, which may improve golf score; however, perceived stress levels and heart rate are not significantly affected (68855). A clinical study in recreationally active adults shows that taking phosphatidylserine 400 mg and caffeine 100 mg daily, along with niacin 28 mg, vitamin C 60 mg, vitamin B1 1.5 mg, vitamin B5 10 mg, vitamin B6 2 mg, vitamin E 12 IU, calcium 100 mg, magnesium 40 mg, and carbohydrates in the form of evaporated cane juice, brown rice syrup, and rice syrup solids 16 grams (Nutravail Technologies) for 14 days modestly reduces post-exercise mood disturbances and perception of fatigue when compared with vitamins and minerals alone. The combination does not appear to improve cognitive function or reaction time (91463). It is not clear if the effect of the combination supplement is due to phosphatidylserine, caffeine, or the combination.
• Attention deficit-hyperactivity disorder (ADHD). It is unclear if oral phosphatidylserine is beneficial for ADHD. Details: A meta-analysis of three generally low-quality randomized clinical trials shows that taking phosphatidylserine 200-300 mg daily for 8-15 weeks modestly improves symptoms of inattention in children with ADHD when compared with placebo. However, there were no significant effects on hyperactivity-impulsivity or on overall ADHD symptoms. Also, two of the three clinical trials included in the analysis investigated the effects of phosphatidylserine in combination with the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (105247). One preliminary clinical trial included in the analysis shows that taking soy-derived phosphatidylserine 200 mg daily for 2 months improves ADHD symptoms, including inattention, hyperactivity-impulsivity, and short-term memory, when compared to baseline in treatment-naïve children with ADHD aged 4-14 years. However, results from this study are limited due to a lack of statistical comparison to the placebo group (89498).
• Cognitive function. Although there is interest in using oral phosphatidylserine for improving cognitive function in healthy adults, there is insufficient reliable information about the clinical effects of phosphatidylserine for this purpose.
• Dementia. It is unclear if oral phosphatidylserine is beneficial for dementia prevention or treatment. Details: In 2003, the FDA determined that it would allow a qualified health claim stating that consuming phosphatidylserine may reduce the risk of dementia in the elderly. However, the FDA has determined that there is very little scientific evidence supporting this claim (102363).
• Depression. It is unclear if oral phosphatidylserine is beneficial for depression. Details: One very small clinical study in elderly adults with depression shows that taking phosphatidylserine 300 mg daily for 30 days modestly improves depression scores when compared to baseline (7113).
• Exercise-induced muscle soreness. It is unclear if oral phosphatidylserine is beneficial for exercise-induced muscle soreness. Details: One small clinical study in athletes shows that taking soybean-derived phosphatidylserine 800 mg daily for 2 weeks during periods of over-training reduces muscle soreness post-exercise when compared with those not taking phosphatidylserine (2264). More evidence is needed to rate phosphatidylserine for these uses.

(Read more about PHOSPHATIDYLSERINE)

POSSIBLY EFFECTIVE

• Dementia. Oral vinpocetine, taken for up to 1 year, might improve cognitive function to a small degree in patients with dementia. Details: While some conflicting evidence exists (1784), several small clinical studies in patients with cognitive impairment due to various causes including dementia, Alzheimer disease, and vascular disease show that taking vinpocetine 5-20 mg three times daily for up to 1 year slightly to modestly improves cognitive function when compared with baseline scores or placebo (1787,1789,82151,82152,82153,82154,82179,82180)(82182,82183,92934,111333). However, most of these studies were published prior to 1990 and used diagnostic and evaluative criteria that limit the applicability of these results to current clinical practice (10221,10827,111333).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. Although there has been interest in using oral vinpocetine for age-related cognitive decline, there is insufficient reliable information about the clinical effects of vinpocetine for this purpose.
• Age-related macular degeneration (AMD). It is unclear if oral vinpocetine is beneficial in patients with AMD. Details: One small clinical study in patients with AMD shows that taking vinpocetine 10 mg daily for 2 months, in conjunction with conventional therapy, improves visual acuity and retinal function when compared with conventional therapy alone (82089).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral vinpocetine for CFS, there is insufficient reliable information about the clinical effects of vinpocetine for this purpose.
• Epilepsy. Although there has been interest in using oral and intravenous vinpocetine for epilepsy, there is insufficient reliable information about the clinical effects of vinpocetine for this purpose.
• Hearing loss. It is unclear if oral or intravenous vinpocetine is beneficial in patients with hearing loss. Details: One small clinical study in patients with acoustic trauma shows that intravenous administration of vinpocetine 10 mg twice daily for 10 days is less effective than nicergoline, an ergot derivative, for improving hearing loss (82147). Another small, open-label clinical study in patients with sensorineural hearing loss shows that taking vinpocetine 10 mg three times daily for 12 months improves some measures of hearing capacity, particularly in months 6-12, when compared to baseline (106845). The validity of these findings is limited by a lack of control group.
• Memory. Small clinical studies suggest that oral vinpocetine might slightly improve memory in healthy individuals. Details: Two very small clinical studies in healthy individuals show that taking vinpocetine 40 mg as a single dose or vinpocetine 10-40 mg three times daily for 2 days enhances some measures of memory when compared with placebo (1796,1797). Additionally, one small clinical study in healthy adults shows that taking a combination product containing vinpocetine 10 mg, ginkgo extract 40 mg, and other ingredients three times daily for 2 weeks improves short-term memory when compared with placebo (8544). It is unclear if these findings are due to vinpocetine, other ingredients, or the combination.
• Menopausal symptoms. Although there has been interest in using oral vinpocetine for menopausal symptoms, there is insufficient reliable information about the clinical effects of vinpocetine for this purpose.
• Motion sickness. Although there has been interest in using oral vinpocetine for motion sickness, there is insufficient reliable information about the clinical effects of vinpocetine for this purpose.
• Stroke. Research on the use of intravenous vinpocetine to improve outcomes in patients recovering from ischemic stroke is mixed. It is unclear if oral vinpocetine is beneficial in these patients. Details: Some small clinical studies show that vinpocetine modestly reduces the residual effects of acute ischemic stroke (1785,10222,82087,82091,82120,82158,82159,82186). However, most clinical studies investigating the use of vinpocetine for stroke have been published in languages other than English and assessed intravenous formulations of vinpocetine not available in the US. One large clinical study shows that intravenous administration of vinpocetine 30 mg once daily for 7 days after an acute stroke, in addition to oral citicoline and aspirin or clopidogrel, seems to improve cerebral blood flow and measures of cognition, neurological function, and quality of life when compared with citicoline plus aspirin or clopidogrel (98226). A meta-analysis of 4 moderate-to-good quality clinical studies that included 837 adults with acute ischemic stroke, some of which are described above, shows that intravenous administration of vinpocetine in addition to standard care, followed by oral administration in some studies, reduces significant disability when compared with standard care. Vinpocetine also seems to improve cognition scores but does not reduce mortality (110744). The included studies used widely heterogeneous dosing regimens and excluded patients with severe strokes. However, a small clinical study not included in the meta-analysis shows that intravenous vinpocetine 20 mg followed by oral vinpocetine 10 mg three times daily for 3 months does not significantly improve neurophysical functioning post-stroke when compared with placebo (82074).
• Tinnitus. It is unclear if oral or intravenous vinpocetine is beneficial in patients with tinnitus. Details: A small observational study in patients with chronic unilateral or bilateral tinnitus has found that intravenous infusion of a specific vinpocetine product (Cavinton) 20 mg plus oral vinpocetine (Cavinton) 10 mg twice daily along with physiotherapy is associated with improved symptoms when compared to baseline (82099). However, a small clinical study in patients with tinnitus due to acoustic trauma shows that intravenous administration of vinpocetine (Cavinton) 10 mg twice daily appears to be less effective than nicergoline, an ergot derivative, for reducing tinnitus (82147).
• Urinary incontinence. It is unclear if oral vinpocetine is beneficial in patients with urinary incontinence. Details: One small, uncontrolled clinical study in patients with urinary incontinence shows that taking vinpocetine 10 mg three times daily for 2 weeks reduces daytime and nighttime frequency of urination when compared to baseline (82041). The validity of these findings is limited by a lack of control group. More evidence is needed to rate vinpocetine for these uses.

(Read more about VINPOCETINE)

EFFECTIVE

• Pyridoxine-dependent epilepsy. Intravenous vitamin B6 is effective for controlling pyridoxine-dependent seizures. Details: Pyridoxine-dependent seizures are a rare type of refractory seizures in neonates that do not respond to anticonvulsant drugs. These seizures are typically controlled within minutes of intravenous administration of pyridoxine, a form of vitamin B6. Pyridoxine-dependent seizures can be due to genetic (autosomal recessive) pyridoxine dependency, or more commonly, a result of the use of high-dose pyridoxine during pregnancy (8197,8198).
• Sideroblastic anemia. Oral vitamin B6 is effective for treating hereditary sideroblastic anemia. Details: Taking vitamin B6 (pyridoxine) orally is effective for treating hereditary sideroblastic anemia (15,9518). Taking the active form of vitamin B6 (pyridoxal-5'-phosphate) also seems to be effective in cases in which the patient does not respond to pyridoxine (93049).
• Vitamin B6 deficiency. Oral vitamin B6 is effective for preventing and treating vitamin B6 deficiency. Details: Taking oral vitamin B6 can prevent and treat vitamin B6 deficiency (15).

LIKELY EFFECTIVE

• Hyperhomocysteinemia. Taking vitamin B6 orally, alone or in combination with folic acid, is effective for reducing hyperhomocysteinemia. Details: Vitamin B6 (pyridoxine) seems to lower homocysteine concentrations when folic acid and vitamin B12 are at physiologic levels or when given with folic acid and vitamin B12 supplements (9451,83042,107136). A combination of vitamin B6 100 mg and folic acid 0.5 mg daily seems to lower homocysteine levels by about 35% and is recommended for people with postprandial hyperhomocysteinemia (1489,9406). Other research shows that taking pyridoxine 50-200 mg daily reduces postprandial homocysteine levels by 32% to 35% (9406,10350). Pyridoxine also seems to reduce homocysteine levels in patients with kidney failure, kidney transplant patients (1489,6884,9414,9415), or patients who receive general anesthesia with nitrous oxide (9481). However, some research in healthy adults suggests that adding pyridoxine to folic acid might not provide any additional benefit over folic acid alone (9400,9405,9409,50145). Hyperhomocysteinemia is considered by some to be an independent risk factor for atherosclerosis, recurrent thromboembolism, deep vein thrombosis, myocardial infarction, and ischemic stroke (1899,3323,9402,9405,9408,9409). However, elevated homocysteine levels may be a marker, as opposed to a cause, of vascular disease (11387,11388). A 5 µmol/L increase in plasma homocysteine increases the risk of cerebrovascular disease by 50% and the odds of coronary heart disease by 60% and 80% in males and females, respectively (9407,9411). However, it is not clear if reducing homocysteine levels results in reduced cardiovascular morbidity and mortality (1489,6883,6884,9308,9400,9405,9409). Folic acid, vitamin B6, and vitamin B12 supplementation can reduce total homocysteine from 13.4 to 11 µmol/L. However, this reduction does not seem to help with secondary prevention of death or myocardial infarction, and some research even suggests an increase in cardiovascular disease (CVD) risk (11387,13482,50423,83050,97619). There is also debate about whether supplementation with homocysteine-lowering B vitamins can reduce the risk of stroke. A number of large clinical studies and meta-analyses show that supplementation with folic acid, vitamin B6, and vitamin B12, alone or in combination, does not reduce the risk of stroke in patients with CVD or impaired renal function (11387,13482,50423,83050,96150). However, a more recent meta-analysis shows that B vitamin supplementation modestly reduces the relative risk of stroke by 10% when compared with placebo in patients at risk for or with a history of CVD (97619). Also, a meta-analysis in patients with a history of stroke shows that B vitamin supplementation modestly reduces the relative risk of stroke recurrence by 13% and the risk of vascular death by 11% when compared with placebo (107136).

POSSIBLY EFFECTIVE

• Antipsychotic-induced hyperprolactinemia. It is unclear if oral vitamin B6 is beneficial for patients with antipsychotic-induced hyperprolactinemia. Details: Clinical research in male patients with hyperprolactinemia who are on a consistent antipsychotic dose shows that taking vitamin B6 300 mg twice daily for 16 weeks reduces serum prolactin levels by 68%, compared with 37% in patients taking aripiprazole 5 mg twice daily. Also, 67% of patients taking vitamin B6 had prolactin levels less than 40 mcg/mL versus 2% of those taking aripiprazole (107128).
• Kidney stones (nephrolithiasis). Oral vitamin B6 seems to decrease urinary oxalate levels and decrease the risk of kidney stone formation in some patients. Details: There is some evidence that taking vitamin B6 (pyridoxine) orally, alone or in combination with magnesium, can decrease urinary oxalate levels in people with type I primary hyperoxaluria, a hereditary disorder (1201,6437,6438,6439,6440,8548,8549,8550). Additionally, a small clinical study in this population suggests that intravenous pyridoxine hydrochloride can reduce urinary oxalate by 25.5% when compared to baseline (90796). In patients with idiopathic hyperoxaluria, taking a combination of pyridoxine 25mg and magnesium oxide 400 mg for 3 months decreases urinary oxalate by approximately 16%, with 68% of patients experiencing a reduction. However, supplementation is less effective than following a low-oxalate diet, which reduces urinary oxalate in 91% of patients by an average of 31% (107127). There is also preliminary evidence that higher pyridoxine intake in females with no history of kidney stones is associated with decreased risk of kidney stone formation (6441), but this association has not been found in males (6442).
• Pregnancy-induced nausea and vomiting. Oral vitamin B6 may reduce nausea and vomiting in some pregnant patients and is sometimes used in combination with doxylamine. Details: While some conflicting evidence exists, most small clinical studies suggest that oral vitamin B6 is effective for improving nausea and vomiting associated with pregnancy when compared with baseline or placebo. However, vitamin B6 may not be as effective as ginger (110459). Two small clinical studies show that taking vitamin B6 (pyridoxine) 25 mg every 8 hours for 3-4 days decreases pregnancy-induced nausea severity and vomiting incidence when compared with placebo (6168,16306). A larger clinical trial shows that taking lower doses of vitamin B6, 10 mg every 8 hours over 5 days, improves pregnancy-induced nausea, but not vomiting, when compared with placebo (6167). A small clinical study in patients with mild to moderate nausea and vomiting shows that taking a higher dose of 40 mg twice daily for 4 days is more effective than placebo, but no better than ginger 500 mg twice daily (99404). The American College of Obstetrics and Gynecology (ACOG) considers vitamin B6 at a dose of 10-25 mg 3 to 4 times daily a first-line treatment for pregnancy-induced nausea and vomiting due to its benign safety profile (111601). However, it is not effective for all patients, such as those with hyperemesis gravidarum, a severe form of pregnancy-induced nausea and vomiting. Adding vitamin B6 20 mg three times daily for 2 weeks to intravenous rehydration, metoclopramide, and thiamine seems to be no more effective than placebo for reducing vomiting in hyperemesis gravidarum (99405). Vitamin B6 is also sometimes used in combination with doxylamine. In fact, a combination of vitamin B6 plus doxylamine (Diclegis or Bonjesta, Duchesnay Inc., and various generics) has been approved by the US Food and Drug Administration (FDA) as a prescription product111601). ACOG recommends vitamin B6 in combination with doxylamine as another first-line treatment option (111601). However, the clinical trial used to obtain FDA approval has some methodological problems, and the significance of the results has been questioned. The improvement in symptom scores seen with Diclegis was less than one point on a 13-point scale, which is unlikely to be clinically significant (97998). Also, some clinical research shows that taking pyridoxine 25 mg and doxylamine 12.5 mg is less effective than ondansetron 4 mg when taken every 8 hours for 5 days. Only 41% of the patients using pyridoxine and doxylamine had a clinically significant reduction in nausea, compared to 92% of patients using ondansetron (90797). The combination of vitamin B6 and doxylamine is also studied with acupuncture. A large clinical study in patients with moderate to severe pregnancy-induced nausea and vomiting conducted in China shows that taking vitamin B6-doxylamine (Diclegis, Duchesnay, Inc) 20 to 40 mg each at bedtime for 14 days in combination with daily acupuncture modestly improves patient-reported nausea and vomiting scores when compared with either intervention alone (111820). However, it is unclear whether this improvement is clinically significant.
• Premenstrual syndrome (PMS). Oral vitamin B6 seems to reduce PMS symptoms. Details: There is some evidence that taking vitamin B6 (pyridoxine) orally can improve symptoms of PMS such as breast pain or tenderness (mastalgia) and depression in some patients. Pyridoxine in doses of at least 50 mg daily, plus magnesium oxide 200 mg daily, seems to relieve PMS-related anxiety and other symptoms (8555,39007,82962). Although some clinicians advocate doses of pyridoxine 200-500 mg daily for PMS, doses of 50-100 mg daily seem to work just as well. There is no apparent dose-response curve for PMS, so the lowest effective dose should be used. Higher doses might increase the risk of side effects (3093).

POSSIBLY INEFFECTIVE

• Age-related cognitive decline. Oral vitamin B6 does not seem to slow age-related cognitive decline. Details: One clinical trial in elderly people with memory complaints shows that taking a combination of B vitamins, including folic acid 0.8 mg, vitamin B12 0.5 mg, and vitamin B6 (form not specified) 20 mg daily for 24 months reduces cerebral atrophy in the gray matter regions associated with Alzheimer disease by up to seven-fold when compared with placebo. However, this protection does not occur in patients with the lowest average blood levels of homocysteine (90374). Furthermore, other clinical research shows that taking vitamin B6 (pyridoxine) 3-75 mg daily in combination with folic acid and vitamin B12 does not improve cognitive function in elderly adults (14392,50225,50510).
• Alzheimer disease. Oral vitamin B6 does not seem to improve cognitive function in patients with Alzheimer disease when used in combination with other B vitamins. Also, oral vitamin B6 does not seem to reduce the risk of developing this condition. Details: Clinical research in patients with probable Alzheimer disease taking routine medications shows that taking vitamin B6 25 mg with folic acid 5 mg and vitamin B12 1 mg daily for 18 months does not have a beneficial effect on cognitive function or the severity of disease when compared with placebo. In this study, all patients were consuming a folate-fortified diet (50319). Also, population research in elderly adults has found that a high intake of vitamin B6 from dietary or supplemental sources is not associated with a decreased risk of Alzheimer disease when compared to lower vitamin B6 intake (13165,15270).
• Carpal tunnel syndrome. Oral vitamin B6 does not seem to reduce symptoms of carpal tunnel syndrome. Details: Most research shows that people with carpal tunnel syndrome are not generally deficient in vitamin B6 and do not benefit from taking vitamin B6 supplements (8203,8937,9448,9450,9478,9482). Although early studies by a single group of researchers, as well as anecdotal reports, suggest that taking vitamin B6 may relieve carpal tunnel symptoms, more reliable research has not supported these findings (8202,9445,9447,9449,9483,15955,83086).
• Cataracts. Oral vitamin B6 does not seem to slow cataract development. Details: Clinical research in females with existing cardiovascular disease (CVD) or at increased risk of CVD shows that taking a combination of folic acid 2.5 mg, vitamin B6 (form not specified) 50 mg, and vitamin B12 1 mg daily for an average of 7.3 years does not reduce the risk of cataracts when compared with placebo. Furthermore, the risk of cataract extraction was increased by 28% (96149).
• Chemotherapy-induced acral erythema. While some conflicting evidence exists, most research suggests that oral or topical vitamin B6 does not seem to prevent or reduce the severity of acral erythema induced by chemotherapy. Details: A meta-analysis of 10 clinical trials and 4 observational studies shows that taking vitamin B6 60-500 mg daily for up to 8 chemotherapy cycles does not prevent chemotherapy-induced acral erythema or reduce the incidence of severe cases when compared with control. Most studies used capecitabine chemotherapy alone or in combination, and one study used pegylated liposomal doxorubicin; however, no subgroup analysis was conducted to differentiate chemotherapy regimens. Results did not seem to vary based on study location, study design, or vitamin B6 dose (104930). However, a more recent preliminary clinical study in patients receiving doxorubicin for multiple myeloma shows that taking vitamin B6 100 mg on the first day of chemotherapy then twice daily for 7 days with each cycle reduces the risk of developing acral erythema by 72%, but does not improve the severity of acral erythema, when compared with no vitamin B6 supplementation (110458). Also, one small, low-quality clinical study suggests that taking vitamin B6 400 mg daily reduces the risk of moderate or severe chemotherapy-induced acral erythema when compared with vitamin B6 200 mg daily; however, the higher dose also seems to be associated with worsened tumor response and increased treatment failure (97620). Topical vitamin B6 has also failed to show benefit. A small clinical study in patients with acral erythema from capecitabine or pegylated liposomal doxorubicin shows that applying vitamin B6 1% cream to affected areas three times daily for 6 weeks does not improve symptoms when compared with placebo (104929).
• Colorectal adenoma. Oral vitamin B6 does not seem to reduce the risk of developing colorectal adenomas. Details: Clinical research shows that taking a combination of B vitamins, including folic acid 2.5 mg, vitamin B6 (pyridoxine) 50 mg, and vitamin B12 1 mg, daily for up to 9.2 years does not reduce the risk of colorectal adenoma in females at high risk of cardiovascular disease when compared with placebo (90389).
• Eclampsia. Oral or intramuscular vitamin B6 does not seem to reduce the risk of eclampsia. Details: Meta-analyses of limited clinical research in pregnant patients show that taking vitamin B6 (pyridoxine), either as 25 mg daily or a single dose of 100 mg orally or intramuscularly, does not reduce the risk of eclampsia when compared with control (83046,96166).
• Osteoporosis. Oral vitamin B6 does not seem to reduce the risk of osteoporotic fractures. Details: Clinical research in patients with cerebrovascular disease shows that taking a combination of B vitamins, including folic acid 2 mg, vitamin B6 (form not specified) 25 mg, and vitamin B12 500 mcg daily for up to 10.5 years does not prevent osteoporotic fractures when compared with placebo (90377). Furthermore, a secondary analysis of two large studies in patients with cardiovascular disease has found that taking vitamin B6 (pyridoxine) 40 mg daily in addition to folic acid and vitamin B12 for 1-3 years is associated with a 42% increased risk of hip fracture over an 11-year period when compared with only folic acid and vitamin B12 (96163). This finding is limited because these studies were not designed to assess the effects of vitamin B6 on fracture risk and the analyses were not adjusted for baseline bone health or fall risk.
• Pre-eclampsia. Oral or intramuscular vitamin B6 does not seem to reduce the risk of pre-eclampsia. Details: Meta-analyses of limited clinical research in pregnant patients show that taking vitamin B6 (pyridoxine), either as 25 mg daily or a single dose of 100 mg orally or intramuscularly, does not reduce the risk of pre-eclampsia when compared with placebo (83046,96166).
• Preterm labor. Oral or intramuscular vitamin B6 does not seem to reduce the risk of preterm labor. Details: Meta-analyses of limited clinical research in pregnant patients shows that taking vitamin B6 (pyridoxine), either as 25 mg daily or a single dose of 100 mg orally or intramuscularly, does not reduce the risk of preterm labor when compared with placebo (83046,96166).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults and children with inflammatory acne shows that taking 1-4 tablets of a specific product (NicAzel, Elorac Inc.) containing vitamin B6 (pyridoxine), nicotinamide, azelaic acid, zinc, copper, and folic acid for 8 weeks reduces inflammatory lesions and improves appearance in 88% and 81% of patients, respectively, when compared to baseline (90800). The validity of these findings is limited by the lack of a comparator group.
• Age-related macular degeneration (AMD). Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large-scale clinical study shows that taking vitamin B6 (pyridoxine) 50 mg, vitamin B12 1000 mcg, and folic acid 2.5 mg daily reduces the risk for AMD in females over 40 years of age with a history of cardiovascular disease (CVD) or with risk factors for CVD. Those who took this combination for an average of 7.3 years had a 34% reduced risk of developing AMD and a 41% reduced risk of visually significant AMD when compared with placebo (14620). It is unclear if this effect is due to vitamin B6, other ingredients, or the combination.
• Angioplasty. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some evidence suggests that vitamin B6 (pyridoxine) 10 mg, folic acid 1 mg, and vitamin B12 400 mcg daily can decrease the rate of restenosis in patients treated with balloon angioplasty (8009,9412). However, this combination does not seem to be as effective for reducing restenosis in patients after coronary stenting (8009). An intravenous loading dose of folic acid, vitamin B6 (pyridoxine), and vitamin B12 followed by oral administration of folic acid 1.2 mcg, vitamin B6 (pyridoxine) 48 mg, and vitamin B12 60 mcg daily after bare metal coronary stenting also does not seem to reduce restenosis and might actually increase restenosis (12150,12151). Due to the lack of evidence of benefit and potential for harm, this combination of vitamins should not be recommended for patients receiving coronary stents (12151). It is unclear if any effects are due to vitamin B6, other ingredients, or the combination.
• Antipsychotic-induced metabolic side effects. It is unclear if oral vitamin B6, as an adjunct to progesterone, is beneficial in patients with antipsychotic-induced amenorrhea. Details: A small clinical study in females with antipsychotic-induced amenorrhea shows that taking vitamin B6 80 mg three times daily for 1 month plus intramuscular progesterone daily for 5 days increases levels of estradiol and follicle stimulating hormone, reduces prolactin levels, and increases the rate of clinical efficacy, defined as the normalization of menstruation and improvement in endocrine indicators, by 14% when compared with progesterone alone (110457).
• Anxiety. It is unclear if oral vitamin B6 is beneficial in patients with anxiety. Details: Clinical research in college students shows that taking vitamin B6 100 mg daily for one month does not reduce anxiety scores when compared with placebo (110453). However, because a diagnosis of anxiety was not a requirement for study participation, it is unclear if these findings can be generalized to patients diagnosed with anxiety.
• Asthma. It is unclear if oral vitamin B6 is beneficial in patients with asthma. Details: Preliminary clinical studies show that taking vitamin B6 (pyridoxine) 200-300 mg daily may improve symptoms of asthma in some patients, but not others, when compared with placebo (7064,7065). Studies have yielded conflicting results, with some research suggesting that it may only be beneficial in children with severe asthma (7065). Additionally, some research suggests that theophylline may lower vitamin B6 levels, although it is unclear if vitamin B6 supplementation is beneficial (4522,7066,9503).
• Atherosclerosis. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with intermediate risk for coronary heart disease shows that taking a specific supplement (Kyolic, Total Heart Health, Formula 108, Wakunga) containing vitamin B6 12.5 mg, aged garlic extract 250 mg, vitamin B12 100 mcg, folic acid 300 mcg, and L-arginine 100 mg daily for 12 months reduces coronary artery calcium progression when compared with placebo (88385). It is unclear if this effect is due to vitamin B6, other ingredients, or the combination.
• Atopic dermatitis (eczema). It is unclear if oral vitamin B6 is beneficial in patients with eczema. Details: A small clinical study in children with eczema shows that taking vitamin B6 (pyridoxine hydrochloride) 50 mg daily for 4 weeks does not reduce symptoms such as redness and itchiness when compared with placebo (83090).
• Attention deficit-hyperactivity disorder (ADHD). It is unclear if oral vitamin B6 is beneficial for ADHD. Details: A small crossover study in children with ADHD shows that taking vitamin B6 600 mg, niacinamide and ascorbic acid 3 grams, and calcium pantothenate 1.2 grams daily for 6 weeks does not improve behavior scores when compared with placebo (9957).
• Autism spectrum disorder. Although there is interest in using oral vitamin B6 for autism, there is insufficient reliable information about the clinical effects of vitamin B6 for this condition.
• Bipolar disorder. It is unclear if oral vitamin B6 is beneficial in patients with bipolar disorder. Details: A small clinical trial in patients with type 1 bipolar disorder who are taking lithium and experiencing an acute episode of mania shows that taking vitamin B6 80 mg daily for 8 weeks does not improve cognitive function or the severity of mania when compared with placebo. Cognitive function was reduced in patients taking vitamin B6; any effect on sleep was unclear (107132).
• Cancer. It is unclear if oral vitamin B6 reduces overall cancer risk. Details: Population research has found that higher dietary intake of vitamin B6 is associated with a 22% reduced risk of cancer, including esophageal, pancreatic, gastric, colorectal, and breast cancer. However, when dietary and supplemental vitamin B6 intake is considered, the inverse association between vitamin B6 and cancer risk is weaker and limited to fewer tumor sites. Furthermore, a meta-analysis of 9 clinical studies shows that taking vitamin B6 3-100 mg orally daily for 2-7.3 years, in combination with vitamin B12 and folate, does not reduce the risk of cancer in patients with cardiovascular disease or kidney failure (96164).
• Cardiovascular disease (CVD). Oral vitamin B6, taken along with other B vitamins, does not seem to improve secondary prevention of death or myocardial infarction in patients with CVD. However, it might slightly lower the risk of stroke. Details: Overall evidence from clinical research and meta-analyses shows that taking vitamin B6 in combination with folic acid and/or vitamin B12 does not seem to help with secondary prevention of death or myocardial infarction in patients with or at risk for CVD (11387,13482,34540,50423,83050,90379,97619). In fact, some research suggests that long-term supplementation with vitamin B6, folic acid, and vitamin B12 for secondary prevention increases the risk of CVD by 20% despite lowering homocysteine levels by 30% (13482). However, some research shows that taking vitamin B6 in combination with other B vitamins modestly reduces the risk of stroke, although results are conflicting (11387,13482,50423,83050,96150,96165,97619,107136). Additionally, it is unclear which specific combination of B vitamins is optimal for reducing stroke risk and which patients are most likely to benefit. In 2001, prior to the publication of the highest quality research on this topic, the US Food and Drug Administration (FDA) approved a qualified health claim stating that, as part of a well-balanced diet that is low in saturated fat and cholesterol, folic acid, vitamin B6, and vitamin B12 may reduce the risk of vascular disease (102368).
• Cognitive function. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A moderate-sized clinical study in healthy adults aged 40-65 years shows that taking a supplement containing vitamin B6, ginkgo leaf, bacopa, and other B vitamins twice daily for 12 weeks does not improve memory or attention when compared with placebo (111334).
• Colorectal cancer. It is unclear if oral vitamin B6 reduces the risk of colorectal cancer. Details: A meta-analysis of observational studies suggests that the highest dietary intake of vitamin B6 is associated with a 20% reduced risk of colorectal cancer when compared with the lowest dietary intake. However, this association was not shown in subgroup analyses of studies conducted in Australia, Europe, or North America (111600). The validity of this analysis is limited by the heterogeneity of the included studies.
• Dental caries. There is limited evidence on the oral use of vitamin B6 for dental decay during pregnancy. Details: Meta-analyses of limited clinical research show that taking vitamin B6 (pyridoxine), 25 mg daily or a single dose of 100 mg orally or intramuscularly, may reduce the risk of dental decay during pregnancy when compared with placebo (83046,96166).
• Depression. It is unclear if oral vitamin B6 reduces the risk of developing depression or improves symptoms of depression. Details: Clinical research in healthy college students shows that taking vitamin B6 100 mg daily for one month does not reduce depression scores when compared with placebo (1104453). However, because a diagnosis of depression was not a requirement for study participation, it is unclear if these findings can be generalized to patients diagnosed with depression. Whether vitamin B6 reduces the risk of developing depression is also unclear. A meta-analysis of population research has found that the highest dietary intake of vitamin B6 is associated with a 19% lower risk of depression when compared with the lowest intake. However, sub-analyses suggest that this association is only relevant in females and not males (107133). In one individual population study in community dwelling older adults included in the analysis, the consumption of at least 1.71 mg of vitamin B6 daily from food was associated with a 43% reduction in the likelihood of becoming depressed when compared with the consumption of 1.33 mg or less daily in females. However, there was no association between vitamin B6 levels and risk of depression in males, and the finding in females was no longer significant when adjusted for total energy intake, since foods rich in vitamin B6 are energy-dense (96168). Another observational longitudinal study in healthy adults starting oral contraceptives containing ethinyl estradiol and levonorgestrel has found that taking vitamin B6 25 mg daily for 6-12 months is associated with a 40% lower risk of depression when compared with no supplementation (90789). Most available studies are cross-sectional in nature, making any conclusions related to causation difficult.
• Diabetes. It is unclear if oral vitamin B6 is beneficial in patients with type 2 diabetes or gestational diabetes. Details: Observational research in Chinese adults with type 2 diabetes has found that dietary intake of vitamin B6 in the highest quartile is associated with 53% lower odds of developing cardiovascular disease, defined as a non-fatal myocardial infarction, non-fatal stroke, or hospitalization for unstable angina, when compared with vitamin B6 intake in the lowest quartile (110452). Small clinical studies in patients with gestational diabetes and vitamin B6 deficiency shows that taking vitamin B6 (pyridoxine) 100 mg daily for 2 weeks improves glucose tolerance and blood glucose levels when compared with baseline (82967,83088). However, there is concern that these findings were confounded by dietary alterations. This benefit was not observed in a subsequent small case series in patients with gestational diabetes (22380).
• Diabetic neuropathy. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research suggests that taking a combination of B vitamins, including folic acid (L-methylfolate), vitamin B12 (methylcobalamin), and vitamin B6 (pyridoxal-5'-phosphate) for 24 weeks does not improve neural dysfunction based on vibration perception when compared with placebo in patients with diabetic neuropathy. However, taking this combination appears to modestly improve neuropathy symptoms and quality of life related to mental functioning when compared with placebo (90375).
• Dysmenorrhea. It is unclear if oral vitamin B6 is beneficial in patients with dysmenorrhea. Details: Preliminary clinical research shows that taking vitamin B6 (form not specified) 200 mg daily reduces pain associated with dysmenorrhea when compared with placebo. However, taking vitamin B6 in combination with magnesium does not reduce pain when compared with placebo (77388).
• Fibromyalgia. It is unclear if oral vitamin B6 is beneficial in patients with fibromyalgia. Details: A small clinical study in patients with fibromyalgia shows that taking vitamin B6 80 mg daily for 8 weeks does not improve pain, disease severity, anxiety, depression, or quality of life when compared with placebo (110454).
• Gastroenteritis-associated nausea and vomiting. It is unclear if oral vitamin B6 is beneficial in children with gastroenteritis. Details: A small clinical study in children aged 6 months to 12 years with acute viral gastroenteritis shows that taking vitamin B6 (form not specified) does not improve symptoms of dehydration or the frequency of vomiting when compared with placebo (90793).
• Hypertension. It is unclear if oral vitamin B6 reduces blood pressure. Details: One small clinical study in patients with essential hypertension shows that taking vitamin B6 (pyridoxine hydrochloride) 5 mg/kg daily for 4 weeks can reduce systolic and diastolic blood pressure when compared with baseline (83091). The validity of this finding is limited by the lack of a control group.
• Hypertriglyceridemia. It is unclear if oral vitamin B6 reduces triglyceride levels. Details: Preliminary clinical research shows that vitamin B6 (form not specified) 50 mg daily for 12 weeks does not reduce triglyceride levels in people with hypertriglyceridemia when compared with placebo. However, vitamin B6 appears to decrease total cholesterol and high-density lipoprotein (HDL) cholesterol by approximately 9% in these patients (59028).
• Infertility. Although there is interest in using oral vitamin B6 for infertility, there is insufficient reliable information about the clinical effects of vitamin B6 for this condition.
• Insomnia. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in healthy adults with self-reported sleep difficulty shows that taking a specific product (LZ Complex3, Sanofi Consumer Healthcare Pty Ltd.) containing vitamin B6, zizyphus extract, hops extract, hydrolyzed milk protein (Lactium), and magnesium oxide nightly, 30 minutes before bed, for 2 weeks does not improve sleep quality, daytime functioning, or physical fatigue when compared with placebo. However, due to the large improvement seen in both the treatment and placebo groups, the effectiveness of this product is unclear (95971).
• Isoniazid-induced neuropathy. It is unclear if oral vitamin B6 prevents the development of neuropathy in patients taking isoniazid. Details: Preliminary clinical research in patients taking isoniazid for tuberculosis shows that taking vitamin B6 (pyridoxine) 6 mg daily reduces the development of neuropathy when compared with control (83068).
• Lactation. It is unclear if oral vitamin B6 helps to suppress postpartum lactation. Details: A meta-analysis of two small clinical trials shows that taking vitamin B6 (pyridoxine) 400-600 mg daily for 6-7 days postpartum does not suppress lactation when compared with no treatment (83047).
• Levetiracetam-induced side effects. While some conflicting evidence exists, several small, low-quality studies suggest that oral vitamin B6 (pyridoxine) may reduce some neuropsychiatric adverse effects related to the use of levetiracetam. Details: In an analysis of case reports, retrospective studies, and a single low-quality prospective study, improvement in levetiracetam-associated neuropsychiatric symptoms occurred in approximately 73% of patients taking pyridoxine (107137). A more recent preliminary clinical trial in children ages 1-17 years shows that taking pyridoxine 10 or 15 mg/kg daily as needed based on symptoms improves behavioral side effects associated with levetiracetam by a small amount when compared with low-dose pyridoxine 0.5 mg/kg daily used as placebo (107124). Also, observational research in children ages 9 months to 14 years has found that taking vitamin B6 is associated with improved behavior and a 44% lower risk of levetiracetam discontinuation when compared with no vitamin B6 supplementation (110455). Some observational research in adults with levetiracetam-associated irritability has found that taking vitamin B6 is associated with an improvement in irritability in 45% of patients when compared to baseline (107129). However, a small clinical trial in adults with epilepsy shows that taking pyridoxine 40 mg daily for 3 weeks does not improve levetiracetam-related psychiatric adverse effects when compared with placebo (110456). This study may have been underpowered to detect differences between groups. Pyridoxine doses used in the studies above have ranged from 50-400 mg daily in children and 40-600 mg daily in adults (107124,107129,107137,110456).
• Lung cancer. It is unclear if dietary or oral vitamin B6 reduces lung cancer risk. Details: Epidemiological research has found that higher serum levels of vitamin B6 in male smokers is associated with a lower risk of lung cancer (9454). Also, people with blood levels of vitamin B6 in the top quartile have a modestly lower risk of lung cancer when compared with those whose levels are in the lowest quartile. The association is stronger for males and for people who have smoked (97999). However, other epidemiological research found that increased dietary intake of vitamin B6 is not associated with a reduced risk of lung cancer (96164).
• Menopausal symptoms. Although there is interest in using oral vitamin B6 for menopausal symptoms, there is insufficient reliable information about the clinical effects of vitamin B6 for this condition.
• Motion sickness. Although there is interest in using oral vitamin B6 for motion sickness, there is insufficient reliable information about the clinical effects of vitamin B6 for this condition.
• Nausea and vomiting. It is unclear if oral vitamin B6 is beneficial for nausea and vomiting in patients using oral contraceptives. Details: An observational longitudinal study in healthy females taking oral contraceptives containing ethinyl estradiol and levonorgestrel has found that taking vitamin B6 25 mg daily for 6-12 months is associated with a 43% reduced risk of nausea when compared with no supplementation (90789).
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral vitamin B6 for patients with NAFLD. Details: A small clinical trial in patients with NAFLD shows that taking vitamin B6 (pyridoxine) 30 mg three times daily for 12 weeks does not reduce levels of liver transaminases or plasma lipids when compared with baseline. However, hepatic fat accumulation was modestly reduced (107130). The validity of this study is limited by the lack of a comparator group.
• Obesity. It is unclear if oral vitamin B6 in beneficial in overweight or obese individuals. Details: A small clinical trial in females with a body mass index (BMI) of at least 25 kg/m² shows that taking vitamin B6 as pyridoxine 80 mg daily for 8 weeks reduces fat mass and improves insulin resistance and triglyceride levels by a small amount when compared with placebo. Although some other anthropometric and metabolic indices were improved when compared with baseline, there was no effect of pyridoxine on body weight, visceral adiposity, or other endpoints when compared with placebo (107131).
• Overall mortality. It is unclear if oral vitamin B6 reduces the risk of overall mortality. Details: Observational research in US adults has found that dietary intake of vitamin B6 in the highest quintile is associated with a 12% to 21% lower risk of all-cause mortality and a 31% to 44% lower risk of cardiovascular mortality when compared with the lowest quintile of dietary vitamin B6 intake (110451).
• Pancreatic cancer. It is unclear if oral vitamin B6 reduces the risk of pancreatic cancer. Details: Observational research has found that higher dietary intake of vitamin B6 is associated with a 37% lower risk of developing pancreatic cancer when compared with lower intake (104927).
• Postpartum depression. It is unclear if oral vitamin B6 is beneficial in patients with postpartum depression. Details: Preliminary clinical research in individuals considered at increased risk for postpartum depression, but without clinical depression, shows that taking vitamin B6 80 mg daily from the 28th week of pregnancy until birth, and then 40 mg daily for one month, reduces symptoms of depression 1.5 months after birth when compared with baseline (measured during the third trimester) and when compared with placebo. However, it is unclear if any of the patients included in the study developed postpartum depression, as there were no changes in overall symptoms in patients taking placebo (107126).
• Restless legs syndrome (RLS). It is unclear if oral vitamin B6 is beneficial in patients with RLS. Details: A small clinical study in adults with RLS who are beginning treatment with pramipexole shows that also taking vitamin B6 40 mg daily for 2 months moderately improves RLS scores and sleep quality scores when compared with pramipexole and placebo (110052).
• Schizophrenia. It is unclear if oral vitamin B6 is beneficial for patients with treatment-resistant schizophrenia. Details: Clinical research in male patients with treatment-resistant schizophrenia who are on a consistent antipsychotic dose shows that adding vitamin B6 300 mg twice daily for 16 weeks modestly improves psychotic symptoms and some measures of cognitive performance when compared with adding aripiprazole 5 mg twice daily (107128). More research is needed to determine if these benefits are clinically relevant.
• Seizures. It is unclear if oral vitamin B6 is beneficial for preventing seizures in patients with glycosylphosphatidylinositol (GPI) deficiency. Details: Observational case series in a small number of children and young adults with GPI deficiency has found that taking vitamin B6 20-30 mg/kg daily for 3-12 months is associated with some reduction in seizure frequency in 9 of 13 patients. However, no patient reached seizure freedom (107125,107135). In one case series, treatment for 12 months was associated with modest developmental improvements in almost all patients (107135). The study patient populations were slightly different in terms of age and underlying genetic causes for GPI deficiency.
• Sickle cell disease. Oral vitamin B6 has only been evaluated in combination with other B vitamins; its effect when used alone is unclear. Details: Preliminary clinical research in adults with sickle cell disease shows that taking vitamin B6 4.2-6 mg, vitamin B12 4.2-6 mcg, and folic acid 700 mcg daily might lower homocysteine levels. However, it is unknown if this will reduce the risk of endothelial damage in these patients (9324).
• Stroke. It is unclear if oral vitamin B6, either alone or with other B vitamins, is beneficial for stroke prevention. Details: There is some debate about whether supplementation with homocysteine-lowering B vitamins, including vitamin B6, can reduce the risk of stroke. A number of clinical studies and meta-analyses show that supplementation with folic acid, vitamin B6, and vitamin B12, alone or in combination, does not reduce the risk of stroke in patients with cardiovascular disease (CVD) or impaired kidney function (11387,13482,50423,83050,96150). However, a more recent meta-analysis of 10 clinical trials, including over 44,000 patients at risk for or with a history of CVD, shows that B vitamin supplementation reduces the relative risk of stroke by 10% when compared with placebo (97619). This meta-analysis differed from some of the earlier analyses due to the inclusion of several additional clinical trials. Also, another meta-analysis of three clinical trials including 9900 patients with a history of stroke shows that B vitamin supplementation reduces the relative risk of stroke recurrence by 13% when compared with placebo, although this finding was determined to have a low level of certainty. Based on two clinical trials, there was also a 17% reduced risk of vascular death and an 11% reduction in the combined risk of stroke, myocardial infarction, and vascular death (107136). In 2001, prior to the publication of the highest quality research on this topic, the US Food and Drug Administration (FDA) allowed a qualified health claim stating that, as part of a well-balanced diet that is low in saturated fat and cholesterol, folic acid, vitamin B6, and vitamin B12 may reduce the risk of vascular disease (102368). Unfortunately, even after the publication of higher quality research, it is still unclear which specific combination of B vitamins is optimal and which patients are most likely to benefit. One network meta-analysis shows that a combination of folic acid and vitamin B6 lowers the risk of stroke more effectively than B vitamin mixtures that include vitamin B12 (96165). However, this analysis is limited because it didn't account for dosing. Exposure to low, but not high amounts, of vitamin B12 (cyanocobalamin) seems to reduce stroke risk (96150).
• Tardive dyskinesia. It is unclear if oral vitamin B6 prevents tardive dyskinesia in patients taking neuroleptic drugs. Details: A small clinical study in patients taking neuroleptic drugs for schizophrenia shows that taking vitamin B6 (form not specified) 400 mg daily seems to improve Parkinsonian, dystonic, and dyskinetic symptoms when compared with placebo (8558).
• Tourette syndrome. Oral vitamin B6 has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small, nonblinded clinical study in children aged 4-17 years with untreated Tourette syndrome or with chronic tic disorder and associated symptoms of anxiety shows that taking a liquid nutritional supplement providing vitamin B6 2.8 mg and L-theanine 200 mg daily for 2 months improves scores on the Yale Global Tic Severity Scale, but does not reduce anxiety, when compared with patients receiving psychoeducation (108555). This study may have been inadequately powered to detect a difference between groups.
• Vincristine-induced neuropathy. Oral vitamin B6 has only been evaluated in combination with pyridostigmine; its effect when used alone is unclear. Details: A small clinical study in children ages 11 months to 13 years with neuropathy due to vincristine treatment for acute lymphoblastic leukemia, shows that taking vitamin B6 150 mg/m2 and pyridostigmine 3 mg/kg twice daily for 3 months is associated with reduced severity of sensory and motor neuropathy when compared with baseline (104928). The validity of this finding is limited by the lack of a control group. More evidence is needed to rate vitamin B6 for these uses.

(Read more about VITAMIN B6)

LIKELY SAFE ...when used orally and appropriately. Acetyl-L-carnitine has been used safely in doses up to 3 grams daily in clinical trials lasting up to 33 months (42,1589,1594,1595,1596,1597,1598,1599,3600,3601) (9105,9791,10076,12743,12745,58375,90755,90756,90759,90761)(90766,90767,90768,95063,95067,111862).

POSSIBLY SAFE ...when used parenterally and appropriately under medical supervision (1591,1592,12743).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term. Acetyl-L-carnitine has been safely used orally in children for up to 6 weeks (90754).

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

(Read more about ACETYL-L-CARNITINE)

POSSIBLY SAFE ...when used orally and appropriately. Deanol has been safely used at doses up to 2 grams daily for up to 4 weeks and doses up to 500 mg daily for up to 3 months (1668,1671,1672,1673,1674,1675,1676,1679,1680,1681). There is insufficient reliable information available about the safety of deanol when used topically.

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

(Read more about DEANOL)

POSSIBLY SAFE ...when used orally and appropriately, short-term. Huperzine A 200-800 mcg daily has been used with apparent safety in clinical trials lasting up to 6 months (3171,3561,4626,93478,93479,93480,93481,93482,93483,93485).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term. Huperzine A has been used with apparent safety in clinical research lasting for 1 month (4626).

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

(Read more about HUPERZINE A)

LIKELY SAFE ...when prescription products are used orally and appropriately (12033). ...when niacinamide supplements are taken orally in doses below the tolerable upper intake level (UL) set by the Institute of Medicine (IOM). The UL of niacinamide is 30 mg daily for adults 18 years of age and 35 mg daily for adults 19 years and older (6243).

POSSIBLY SAFE ...when used orally in doses greater than 30 mg but less than 900 mg daily. The European Food Safety Authority has set the tolerable upper intake level (UL) of niacinamide at 900 mg daily (104937). However, oral niacinamide has been safely used in doses up to 1500 mg daily for 12 weeks in some clinical trials (25561,94188,98940,107709,110502). ...when used topically and appropriately for up to 12 weeks (5940,93360,110498,110501).

CHILDREN: LIKELY SAFE
when used orally and appropriately. Niacinamide has been safely used in children for up to 7 years in doses below the tolerable upper intake level (UL) (4874,9957). The UL of niacinamide for children by age is: 1-3 years, 10 mg daily; 4-8 years, 15 mg daily; 9-13 years, 20 mg daily; 14-18 years, 30 mg daily (6243).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts that do not exceed the tolerable upper intake level (UL) for niacinamide. The UL of niacinamide during pregnancy and lactation is 30 mg daily for those 14-18 years of age and 35 mg daily for those 19 years and older (6243). There is insufficient reliable information available about the safety of larger oral doses of niacinamide or topical niacinamide; avoid using.

(Read more about NIACINAMIDE)

POSSIBLY SAFE ...when used orally and appropriately. Phosphatidylserine has been used with apparent safety at dose of up to 300 mg daily for up to 6 months (2255,2437,2438,2439,2440,2441,7118,15539,68855).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term (7117). Phosphatidylserine has been used with apparent safety in clinical research in doses of 200-300 mg daily for up to 4 months in children aged 4-18 years (7117,89498).

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

(Read more about PHOSPHATIDYLSERINE)

POSSIBLY SAFE ...when used orally and appropriately for up to 12 months (1784,1788,82041,82074,82089,82091,82120,82121,82151,82152)(82153,82154,82179,82180,82182,82183,104522,106845,110744). ...when used intravenously and appropriately, short-term (82074,82099,82147,82158,82159,82186,110744).

PREGNANCY: POSSIBLY UNSAFE
when used orally. In June 2019, the US Food and Drug Administration (FDA) issued a statement of warning that those who are pregnant or who could become pregnant should avoid vinpocetine (95751). In rats, vinpocetine has been associated with an increased risk of miscarriage at a dose of 60 mg/kg daily and with reduced fetal weight and increased incidence of birth defects at a dose of 5-20 mg/kg. Based on pharmacokinetic analyses, a daily vinpocetine dose of 10 mg in humans is comparable to a daily dose of 5 mg/kg in rats (99701).

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about VINPOCETINE)

LIKELY SAFE ...when used orally and appropriately in doses that do not exceed the tolerable upper intake level (UL) of 100 mg daily for adults (15). ...when used parenterally and appropriately. Injectable vitamin B6 (pyridoxine) is an FDA-approved prescription product (15).

POSSIBLY SAFE ...when used orally and appropriately in doses of 101-200 mg daily (6243,8558).

POSSIBLY UNSAFE ...when used orally in doses at or above 500 mg daily. High doses, especially those exceeding 1000 mg daily or total doses of 1000 grams or more, pose the most risk. However, neuropathy can occur with lower daily or total doses (6243,8195). ...when used intramuscularly in high doses and frequency due to potential for rhabdomyolysis (90795).

CHILDREN: LIKELY SAFE
when used orally and appropriately (3094).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately in amounts exceeding the recommended dietary allowance (5049,8579,107124,107125,107135).

CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses, long-term (3094).

PREGNANCY: LIKELY SAFE
when used orally and appropriately. A special sustained-release product providing vitamin B6 (pyridoxine) 75 mg daily is FDA-approved for use in pregnancy. Vitamin B6 (pyridoxine) is also considered a first-line treatment for nausea and vomiting in pregnancy by the American College of Obstetrics and Gynecology (111601). However, it should not be used long-term or without medical supervision and close monitoring.

PREGNANCY: POSSIBLY UNSAFE
when used orally in excessive doses. There is some concern that high-dose maternal vitamin B6 (pyridoxine) can cause neonatal seizures (4609,6397,8197).

LACTATION: LIKELY SAFE
when used orally in doses not exceeding the recommended dietary allowance (RDA) (3094). The RDA in lactating women is 2 mg daily. There is insufficient reliable information available about the safety of vitamin B6 when used in higher doses in breast-feeding women.

(Read more about VITAMIN B6)

ACENOCOUMAROL (Sintrom) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, acetyl-L-carnitine might increase the anticoagulant effects of acenocoumarol.  Details L-carnitine, the parent compound of acetyl-L-carnitine, might enhance the anticoagulant effects of acenocoumarol, an oral anticoagulant that is similar to warfarin, but shorter-acting (9878,12165). There are at least two case reports of INR elevation when L-carnitine was taken with acenocoumarol. 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). It is unclear if such an interaction would also occur with acetyl-L-carnitine.

SEROTONERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, acetyl-L-carnitine might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders, when taken with serotonergic drugs.  Details Animal research shows that acetyl-L-carnitine can increase levels of serotonin in the brain (95065).

THYROID HORMONE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, acetyl-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). It is unclear if such an interaction would occur with acetyl-L-carnitine.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, acetyl-L-carnitine might increase the anticoagulant effects of warfarin.  Details L-carnitine, the parent compound of acetyl-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 acetyl-L-carnitine and warfarin.

(Read more about ACETYL-L-CARNITINE)

ANTICHOLINERGIC DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, deanol might decrease the effectiveness of anticholinergic drugs.  Details Deanol is thought to increase acetylcholine levels (1669).

CHOLINERGIC DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, deanol might increase the effects and adverse effects of cholinergic drugs.  Details Deanol is thought to increase acetylcholine levels (1669).

(Read more about DEANOL)

ANTICHOLINERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, huperzine A might decrease the effects of anticholinergic drugs.  Details Huperzine A has acetylcholinesterase (AChE) inhibiting effects. In animal models, huperzine A reversed cognitive deficits induced by scopolamine, an anticholinergic drug (3134,3135,55692).

CHOLINERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concurrent use of huperzine A with cholinergic drugs might increase the effects and side effects of these medications.  Details Huperzine A can inhibit acetylcholinesterase (AChE) and might cause cumulative effects if used with cholinergic drugs (3131).

(Read more about HUPERZINE A)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, niacinamide may have additive effects when used with anticoagulant or antiplatelet drugs, especially in patients on hemodialysis.  Details Several cases of thrombocytopenia have been reported for hemodialysis patients treated with niacinamide 1 gram daily. Hemodialysis patients receiving niacinamide had almost a three-fold higher risk of developing thrombocytopenia when compared with those receiving placebo (25563,98940).

CARBAMAZEPINE (Tegretol) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Niacinamide might increase the levels and adverse effects of carbamazepine.  Details Plasma levels of carbamazepine were increased in two children given high-dose niacinamide, 60-80 mg/kg/day. This might be due to inhibition of the cytochrome P450 enzymes involved in carbamazepine metabolism (14506). There is not enough data to determine the clinical significance of this interaction.

PRIMIDONE (Mysoline) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Niacinamide might increase the levels and adverse effects of primidone.  Details Case reports in children suggest niacinamide 60-100 mg/kg/day reduces hepatic metabolism of primidone to phenobarbital, and reduces the overall clearance rate of primidone (14506); however, there is not enough data to determine the clinical significance of this potential interaction.

(Read more about NIACINAMIDE)

ANTICHOLINERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, phosphatidylserine might decrease the effectiveness anticholinergic drugs.  Details Phosphatidylserine is thought to increase acetylcholine levels (2437,8857,8858), which could theoretically interfere with the activity of anticholinergic agents.

CHOLINERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, phosphatidylserine might have additive effects with cholinergic drugs.  Details Phosphatidylserine is thought to increase acetylcholine levels (2437,8857,8858), which could theoretically lead to additive cholinergic effects when used with cholinergic drugs.

(Read more about PHOSPHATIDYLSERINE)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Vinpocetine might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.  Details Clinical research shows that vinpocetine decreases red blood cell aggregation, as well as plasma and whole blood viscosity. This effect has been seen with intravenous vinpocetine 1 mg/kg and oral vinpocetine 30 mg daily (82101,82119). Vinpocetine also seems to have antiplatelet effects (1801,10061,82117).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, vinpocetine might increase levels of drugs metabolized by CYP2C9.  Details In vitro research shows that vinpocetine weakly inhibits CYP2C9 (92933). However, this effect has not been reported in humans.

WARFARIN (Coumadin) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Vinpocetine might modestly increase the risk of bleeding when taken with warfarin.  Details Clinical research shows that the combination of warfarin and vinpocetine leads to slight increases in prothrombin time and the area under the concentration curve for warfarin. However, these increases were small, and researchers suggest that this interaction is not likely to be clinically significant in most patients (10829).

(Read more about VINPOCETINE)

AMIODARONE (Cordarone) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, vitamin B6 might increase the photosensitivity caused by amiodarone.  Details Despite initial case reports suggesting that pyridoxine may have a protective effect against amiodarone-induced photosensitivity, preliminary clinical research suggests that pyridoxine may actually exacerbate this adverse effect (8892,8893).

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, vitamin B6 may have additive effects when used with antihypertensive drugs.  Details Research in hypertensive rats shows that vitamin B6 can decrease systolic blood pressure (30859,82959,83093). Similarly, clinical research in patients with hypertension shows that taking high doses of vitamin B6 may reduce systolic and diastolic blood pressure, possibly by reducing plasma levels of epinephrine and norepinephrine (83091).

LEVODOPA Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = D Vitamin B6 may increase the metabolism of levodopa when taken alone, but not when taken in conjunction with carbidopa.  Details Vitamin B6 (pyridoxine) enhances the metabolism of levodopa, reducing its clinical effects. However, this interaction does not occur when carbidopa is used concurrently with levodopa (Sinemet). Therefore, it is not likely to be a problem in most people (3046).

PHENOBARBITAL (Luminal) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D High doses of vitamin B6 may reduce the levels and clinical effects of phenobarbital.  Details Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenobarbital, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenobarbital to avoid high doses of vitamin B6 (3046,10801).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D High doses of vitamin B6 may reduce the levels and clinical effects of phenytoin.  Details Preliminary clinical evidence suggests that vitamin B6 200 mg daily can reduce plasma levels of phenytoin, possibly by increasing metabolism. It is not known whether lower doses have any effect. Advise people taking phenytoin to avoid high doses of vitamin B6 (3046,10801).

(Read more about VITAMIN B6)

General ...Orally, acetyl-L-carnitine is generally well tolerated.
Most Common Adverse Effects:
Orally: Agitation, dry mouth, headache, insomnia, and reduced appetite. A metabolite of acetyl-L-carnitine has been reported to cause a fishy odor of the urine, breath, and sweat.

Cardiovascular ...Orally, one patient in a pharmacokinetic study reported high blood pressure 8 hoursafter taking acetyl-L-carnitine 500 mg; however, it is unclear if this was due to acetyl-L-carnitine or another factor (95061).

Dermatologic ...Orally, a combination of acetyl-L-carnitine and alpha-lipoic acid may cause rash (90441).

Gastrointestinal ...Orally, acetyl-L-carnitine may cause nausea, vomiting, diarrhea, constipation, hiccups, abdominal distension and gastrointestinal upset or pain. However, gastrointestinal symptoms do not usually occur more often in patients receiving acetyl-L-carnitine than in patients receiving placebo (1596,1599,12743,13007,58922,90755,95063,95067,111889,111894). Acetyl-L-carnitine may also cause dry mouth and anorexia (58342). When taken orally, a combination of acetyl-L-carnitine and alpha-lipoic acid may cause diarrhea, constipation, and dyspepsia (90441).

Neurologic/CNS ...Orally, acetyl-L-carnitine may cause headache and insomnia (90760,90767,95063). In one clinical trial, two patients with antiretroviral toxic neuropathy reported paresthesia, pain, and neuropathy after taking acetyl-L-carnitine 1000 mg daily (58342). A case of mania has been reported for a patient with bipolar I disorder currently in remission. The patient presented with symptoms after taking multiple supplements for the past 4 weeks including acetyl-L-carnitine 1000 mg twice daily. The symptoms appeared 3 days after beginning to take acetyl-L-carnitine and worsened over the next week. The patient had increased speech rate and volume and reported increased energy levels and racing thoughts. The patient's parent reported irritability and an increase in loud behaviors at home, similar to a previous episode of mania. The patient was advised to discontinue acetyl-L-carnitine, and the manic symptoms disappeared 3 days later (95062).

Psychiatric ...Orally, acetyl-L-carnitine may cause agitation (restlessness and motor overactivity) (1596,1599,12743,13007). Side effects reported in people with Alzheimer disease include psychiatric disturbances such as depression, mania, confusion and aggression, but it is not clear whether these are due to acetyl-L-carnitine or the condition itself (1594,1595,1596,1597,1598,1599,9105,10391).

Other ...One of the metabolites of acetyl-L-carnitine can cause the urine, breath, and sweat to have a fishy odor (12756). Also, foul smelling urine has been reported following oral use of a combination of acetyl-L-carnitine and alpha-lipoic acid (90441).

(Read more about ACETYL-L-CARNITINE)

General ...Orally, deanol seems to be well tolerated (1668,1671,1672,1673,1674,1675,1676,1679,1680,1681). However, deanol has been reported to cause constipation, diarrhea, urticaria, headache, drowsiness, insomnia, overstimulation, lucid dreams, confusion, motor retardation, depression, hypomania, and an increase in schizophrenia symptoms (1674,1680,1684,1685,1686,2706).
Most Common Adverse Effects:
Orally: Abdominal cramps, abdominal pain, diarrhea, drowsiness, nausea, vomiting.

Cardiovascular ...Orally, small elevations in blood pressure have been reported in some patients taking deanol up to 1800 mg daily. These effects improved after deanol discontinuation (1680).

Gastrointestinal ...Orally, deanol has been reported to cause diarrhea, abdominal cramps, abdominal pain, nausea, and vomiting (1674,1680).

Musculoskeletal ...Orally, deanol up to 1800 mg daily has been reported to cause motor retardation in a small number of patients. This effect improved after deanol discontinuation (1680).

Neurologic/CNS ...Orally, deanol has been reported to cause drowsiness, apathy, and confusion (1674,1680). In one case report, a physician promoted the use of deanol to induce lucid dreams, which may be considered an undesirable outcome for some patients (1686).

Psychiatric ...Orally, taking deanol at doses greater than 1000 mg daily has been reported to cause mood changes, including depression and hypomania, in patients with psychiatric conditions (1685). Deanol 1500 mg daily has been reported to increase schizophrenic symptoms in patients with chronic schizophrenia (1674).

(Read more about DEANOL)

General ...Orally, huperzine A seems to be well tolerated. There is currently a limited amount of information about the tolerability of intramuscular huperzine A.
Most Common Adverse Effects:
All ROAs: Huperzine A can cause dose-dependent cholinergic side effects such as blurred vision, constipation, diarrhea, dizziness, dry mouth, insomnia, nausea, sweating, and vomiting.

Cardiovascular ...Orally, huperzine A might cause decreased heart rate (3138,93482). There are two cases reported where consumption of a tea mistakenly brewed from Lycopodium selago, a source of huperzine A, has resulted in significant cholinergic toxicity, including hypertension (13193).

Gastrointestinal ...Orally, huperzine A can cause cholinergic side effects such as nausea, vomiting, diarrhea, and anorexia (93480,93481,93482,93483). Constipation and thirst have also been reported (93482,93483). In two case reports, consumption of a tea mistakenly brewed from Lycopodium selago, a source of huperzine A, has resulted in significant cholinergic toxicity, including vomiting and diarrhea (13193).

Musculoskeletal ...In two case reports, consumption of a tea mistakenly brewed from Lycopodium selago, a source of huperzine A, has resulted in significant cholinergic toxicity, including leg cramps (13193).

Neurologic/CNS ...Orally, huperzine A can cause cholinergic side effects such as dizziness (3140,55613,93481,93482) and sweating (93482). Huperzine A can also cause hyperactivity and insomnia (3138,3140,55613,93482). Fainting has also been reported (4624). In two case reports, consumption of a tea mistakenly brewed from Lycopodium selago, a source of huperzine A, has resulted in significant cholinergic toxicity, including sweating and slurred speech (13193).

(Read more about HUPERZINE A)

General ...Orally, niacinamide is well tolerated in amounts typically found in food. When used topically and orally in higher doses, niacinamide seems to be generally well tolerated.
Most Common Adverse Effects:
Orally: Dizziness, drowsiness, itching, gastrointestinal disturbances, headache, and rash.
Topically: Burning sensation, itching, and mild dermatitis.

Dermatologic ...Orally, large doses of niacinamide are associated with occasional reports of rashes, itching, and acanthosis nigricans (4880,11695,11697,14504,107709). Topically, application of niacinamide in a cream has been reported to cause a burning sensation, itching and pruritus, crusting, and mild dermatitis (93357,93360,110501,110498).

Endocrine ...Orally, niacinamide in high doses, 50 mg/kg daily, has been associated with modestly higher insulin requirements in patients with type 1 diabetes, when compared with taking niacinamide 25 mg/kg daily. Theoretically, high-dose niacinamide might increase insulin resistance, although to a lesser extent than niacin (4881,14512).

Gastrointestinal ...Orally, large doses of niacinamide can cause gastrointestinal disturbances including nausea, vomiting, heartburn, anorexia, epigastric pain, flatulence, and diarrhea (6243,11694,11695,11696,11697,107709).

Hematologic ...Orally, niacinamide supplementation might increase the risk for thrombocytopenia in patients undergoing hemodialysis (98940,107709). A meta-analysis of small clinical studies shows that taking niacinamide during hemodialysis to reduce phosphate levels is associated with a 2.8-fold increased risk for thrombocytopenia when compared with placebo. In one of the included studies, platelet levels returned to normal within 20 days after niacinamide discontinuation (98940).

Hepatic ...Orally, older reports of elevated liver function tests with high doses of niacinamide (3 grams or more daily) have raised concerns about liver toxicity. However, newer studies have not reported this concern; it is possible that some of these cases were due to contamination with niacin (4880,11694,11695,14503).

Neurologic/CNS ...Orally, large doses of niacinamide can cause dizziness, drowsiness, and headaches (11694,11695,11696,11697,107709).

(Read more about NIACINAMIDE)

General ...Orally, phosphatidylserine is generally well tolerated.
Most Common Adverse Effects:
Orally: Flatulence, gastrointestinal upset, headache, insomnia, and nausea.

Gastrointestinal ...Orally, phosphatidylserine can cause gastrointestinal upset such as flatulence or nausea. Gastrointestinal upset can occur at doses of 200-300 mg/day (7116,7121,15539,68862,90711).

Neurologic/CNS ...Orally, phosphatidylserine can cause insomnia. Insomnia is more likely to occur with a higher dose of 600 mg (7121,68844). Headache has also been reported (90711).

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General ...Orally and intravenously, vinpocetine seems to be well tolerated.
Most Common Adverse Effects:
Orally: Anxiety, dizziness, headache, flushing, gastric discomfort, sleep disturbances, and urticaria.
Serious Adverse Effects (Rare):
Orally: Agranulocytosis, arrhythmias, and seizures.
Intravenously: Arrhythmias.

Cardiovascular ...Orally, tachycardia, multifocal extra systoles, transient hypotension and hypertension, and palpitations have been reported with vinpocetine in clinical trials (1789,82118,82152,92936). One case of severe hypotension has been reported with oral vinpocetine (106845). Vinpocetine has also been reported to cause atrial fibrillation and ventricular arrhythmias, with the highest incidence occurring after intravenous or intramuscular administration (1789,82128,68753,82123).

Dermatologic ...Orally, vinpocetine has been reported to cause flushing, skin rash, and urticaria (82118,82120,82153,106845). Intravenously, vinpocetine has been associated with one report of allergic dermatitis (98226).

Gastrointestinal ...Orally, gastric discomfort, upper abdominal pain, nausea, diarrhea, constipation, vomiting, heartburn, difficulty swallowing, and dry mouth have been reported with vinpocetine (1787,1789,10061,10221,82120,82154,82155,92936,106845). Intravenously, diarrhea has been reported with vinpocetine (98226).

Hematologic ...Orally, vinpocetine has been associated with one case report of agranulocytosis (82156) and one case report of ecchymoma of the eyelid in a 60-year-old male 12 hours after a botulinum toxin injection. The patient had been taking vinpocetine 30 mg daily and aspirin 100 mg daily (112878).

Neurologic/CNS ...Orally, anxiety, drowsiness, headache, sleep disturbance, nervousness, excitation, hyperirritability, epileptiform convulsion, and vertigo have been reported with vinpocetine (1787,10221,68772,82118,82120,82151,82152,82154,92936,106845). Intravenously, dizziness has been reported with vinpocetine (98226).

Ocular/Otic ...Orally, vinpocetine has been associated with one case of eyelid edema (106845). Also, one case reports ecchymoma of the eyelid in a 60-year-old male 12 hours after a botulinum toxin injection. The patient had been taking vinpocetine 30 mg daily and aspirin 100 mg daily (112878).

Pulmonary/Respiratory ...Orally, vinpocetine has been associated with one case of severe dyspnea (106845).

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General ...Orally or by injection, vitamin B6 is well tolerated in doses less than 100 mg daily.
Most Common Adverse Effects:
Orally or by injection: Abdominal pain, allergic reactions, headache, heartburn, loss of appetite, nausea, somnolence, vomiting.
Serious Adverse Effects (Rare):
Orally or by injection: Sensory neuropathy (high doses).

Dermatologic ...Orally, vitamin B6 (pyridoxine) has been linked to reports of skin and other allergic reactions and photosensitivity (8195,9479,90375). High-dose vitamin B6 (80 mg daily as pyridoxine) and vitamin B12 (20 mcg daily) have been associated with cases of rosacea fulminans characterized by intense erythema with nodules, papules, and pustules. Symptoms may persist for up to 4 months after the supplement is stopped, and may require treatment with systemic corticosteroids and topical therapy (10998).

Gastrointestinal ...Orally or by injection, vitamin B6 (pyridoxine) can cause nausea, vomiting, heartburn, abdominal pain, mild diarrhea, and loss of appetite (8195,9479,16306,83064,83103,107124,107127,107135). In a clinical trial, one patient experienced infectious gastroenteritis that was deemed possibly related to taking vitamin B6 (pyridoxine) orally up to 20 mg/kg daily (90796). One small case-control study has raised concern that long-term dietary vitamin B6 intake in amounts ranging from 3.56-6.59 mg daily can increase the risk of ulcerative colitis (3350).

Hematologic ...Orally or by injection, vitamin B6 (pyridoxine) can cause decreased serum folic acid concentrations (8195,9479). One case of persistent bleeding of unknown origin has been reported in a clinical trial for a patient who used vitamin B6 (pyridoxine) 100 mg twice daily on days 16 to 35 of the menstrual cycle (83103). It is unclear if this effect was due to vitamin B6 intake.

Musculoskeletal ...Orally or by injection, vitamin B6 (pyridoxine) can cause breast soreness or enlargement (8195).

Neurologic/CNS ...Orally or by injection, vitamin B6 (pyridoxine) can cause headache, paresthesia, and somnolence (8195,9479,16306). Vitamin B6 (pyridoxine) can also cause sensory neuropathy, which is related to daily dose and duration of intake. Doses exceeding 1000 mg daily or total doses of 1000 grams or more pose the most risk, although neuropathy can occur with lower daily or total doses as well (8195). The mechanism of the neurotoxicity is unknown, but is thought to occur when the liver's capacity to phosphorylate pyridoxine via the active coenzyme pyridoxal phosphate is exceeded (8204). Some researchers recommend taking vitamin B6 as pyridoxal phosphate to avoid pyridoxine neuropathy, but its safety is unknown (8204). Vitamin B6 (pyridoxine) neuropathy is characterized by numbness and impairment of the sense of position and vibration of the distal limbs, and a gradual progressive sensory ataxia (8196,10439). The syndrome is usually reversible with discontinuation of pyridoxine at the first appearance of neurologic symptoms. Residual symptoms have been reported in patients taking more than 2 grams daily for extended periods (8195,8196). Tell patients daily doses of 100 mg or less are unlikely to cause problems (3094).

Oncologic ...In females, population research has found that a median intake of vitamin B6 1. 63 mg daily is associated with a 3.6-fold increased risk of rectal cancer when compared with a median intake of 1.05 mg daily (83024). A post-hoc subgroup analysis of results from clinical research in adults with a history of recent stroke or ischemic attack suggests that taking folic acid, vitamin B12, and vitamin B6 does not increase cancer risk overall, although it was associated with an increased risk of cancer in patients who also had diabetes (90378). Also, in patients with nasopharyngeal carcinoma, population research has found that consuming at least 8.6 mg daily of supplemental vitamin B6 during treatment was associated with a lower overall survival rate over 5 years, as well as a reduced progression-free survival, when compared with non-users and those with intakes of up to 8.6 mg daily (107134).

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