Flax Seed Oil 1,000 mg by Windmill Natural Vitamins

POSSIBLY INEFFECTIVE

• Hyperlipidemia. Clinical research suggests that alpha-linolenic acid does not lower lipid levels in adults with hyperlipidemia. Details: A meta-analysis of 20 small clinical trials in patients with hyperlipidemia shows that taking foods or supplements containing alpha-linolenic acid does not reduce lipid levels when compared with control (104256). The findings from this analysis are limited by the heterogeneity of the alpha-linolenic acid supplementation regimens and patient populations.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Atherosclerosis. Some research suggests that increasing dietary alpha-linolenic acid intake may decrease atherosclerosis. Details: Epidemiological research in White adults has found that high dietary intake of linolenic acid is associated with reduced calcified atherosclerotic plaques in the coronary arteries. Most dietary linolenic acid is alpha-linolenic acid (only a small fraction is gamma-linolenic acid). For every gram of linolenic acid consumed, risk of coronary artery calcification appears to decrease by 62% (12990). The effects of linolenic acid intake in other populations are unclear.
• Atopic dermatitis (eczema). Although there is interest in using oral alpha-linolenic acid (ALA) for atopic dermatitis, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Attention deficit-hyperactivity disorder (ADHD). It is unclear if alpha-linolenic acid is beneficial in patients with ADHD. Details: Small clinical trials show that taking alpha-linolenic acid does not improve symptoms of previously untreated ADHD in children aged 6-16 years. Taking alpha-linolenic acid 1 gram daily for 8 weeks, or taking a combination of alpha-linolenic acid 60 mg, linoleic acid 240 mg, mineral oil 95 mg, and alpha-tocopherol 5 mg twice daily for 7 weeks does not affect ADHD symptom scores when compared with placebo (100660,100661). However, these studies might have been inadequately powered to detect a difference between groups.
• Cancer. It is unclear if increased dietary intake of alpha-linolenic acid affects mortality in patients with cancer. Details: A large meta-analysis of prospective, observational studies has found that high dietary intake of alpha-linolenic acid is associated with a 6% increased risk of mortality from cancer when compared with low dietary intake of alpha-linolenic acid (106661).
• Cardiovascular disease (CVD). Population research has found that increased dietary intake of alpha-linolenic acid may have some benefit for CVD, but results from clinical research are generally less positive. Details: A large meta-analysis of prospective, observational studies has found that high dietary intake of alpha-linolenic acid is associated with an 8% or 11% reduced risk of mortality from CVD or coronary heart disease (CHD), respectively, when compared with low dietary intake of alpha-linolenic acid. A dose-response analysis and meta-analysis show that a 1-gram increase in daily dietary intake is associated with a 5% reduction in CVD mortality (106661,107741). Other population research has found that consumption of 1-2 grams of dietary alpha-linolenic acid daily is associated with a reduced risk of a first myocardial infarction (MI) by as much as 59% in both males and females (7152,7156). The risk of fatal ischemic heart disease is reduced by 65% in females (7153). In patients who have had a previous MI, following a Mediterranean diet rich in alpha-linolenic acid (1.2-1.6 grams daily) and low in saturated fat and cholesterol for 27 months appears to reduce the risk for a second MI by 73% and the risk for death from any cause by 70% when compared to the standard postinfarction diet (7150). Overall, increasing dietary intake of alpha-linolenic acid by 1-1.2 grams daily appears to reduce the risk of fatal coronary heart disease by 20% in people with no history of heart disease and by 20% or more in people with existing heart disease (12978,91403). However, clinical research has not supported these findings. A meta-analysis of a small number of low to moderate quality clinical studies shows that higher intake of alpha-linolenic acid has little to no benefit for primary prevention of CVD, and does not reduce all-cause mortality, CVD mortality, or CHD events. Any reductions in CVD mortality, arrhythmias, or CHD events in individual trials are very small (103955). This may be due in part to the difficulty in separating the effects of alpha-linolenic acid from those of other dietary, lifestyle, or drug interventions (12917). Some research suggests alpha-linolenic acid has a greater effect on coronary heart disease when intake of fish oils is low (12989).
• Chronic obstructive pulmonary disease (COPD). Although there is interest in using oral alpha-linolenic acid (ALA) for COPD, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Cognitive function. It is unclear if oral alpha-linolenic acid improves cognitive function in healthy adults.
• Crohn disease. Although there is interest in using oral alpha-linolenic acid (ALA) for Crohn disease, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Crohn disease. Although there is interest in using oral alpha-linolenic acid (ALA) for Crohn disease, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Depression. It is unclear if oral alpha-linolenic acid is beneficial in patients with depression. Details: Clinical research in patients aged 60-80 years who have had a myocardial infarction shows that consuming margarine containing alpha-linolenic acid 2 grams daily for 40 months does not reduce symptoms of depression when compared with placebo margarine (104978).
• Diabetes. It is unclear if oral alpha-linolenic acid is beneficial in patients with diabetes. Details: Epidemiological research involving overweight and obese individuals has found that eating at least 1.69 grams alpha-linolenic acid daily is associated with a 45% to 47% reduced risk of developing type 2 diabetes when compared with eating only 0.73 grams daily. However, higher intake of alpha-linolenic acid does not appear to be associated with a reduced risk of diabetes in people who are not overweight (101025). In patients with diabetes, epidemiological research shows that lower intake of alpha-linolenic acid is associated with an increased risk of diabetic nephropathy (101024). However, a meta-analysis of clinical research in adults with diabetes who are stable on oral antidiabetic medications shows that adding alpha-linolenic acid 1.5-7.4 grams daily, in the form of flaxseed oil, walnuts, or chia seeds, to a regular diet for 2-12 months does not improve glycemic control when compared with placebo (98002).
• Influenza. Although there is interest in using oral alpha-linolenic acid (ALA) for influenza, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Hypertension. Some research suggests that increasing dietary alpha-linolenic acid may decrease the risk of hypertension. Details: Epidemiological research has found that high dietary intake of linolenic acid is associated with a reduced risk of hypertension in White adults. Most dietary linolenic acid is alpha-linolenic acid (only a small fraction is gamma-linolenic acid). Eating a diet high in linolenic acid seems to reduce the risk of hypertension by about 33% (12991). The effects of linolenic acid intake in other populations are unclear.
• Kidney transplant. Observational research suggests that alpha-linolenic acid is not beneficial after a kidney transplant, and may actually increase the risk of mortality. Details: Epidemiological research has found that dietary intake of alpha-linolenic acid is not associated with improved graft function in kidney transplant. However, kidney transplant recipients in the highest tertile of alpha-linolenic acid intake appear to have a 2.2-fold increased risk of death from any cause when compared with those in the lowest tertile of dietary intake (98003). It is not clear whether this difference is specifically due to alpha-linolenic acid intake or to total fat intake.
• Migraine headache. Although there is interest in using oral alpha-linolenic acid (ALA) for migraine headache, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Multiple sclerosis. Although there is interest in using oral alpha-linolenic acid (ALA) for MS, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Overall mortality. It is unclear if increased dietary intake of alpha-linolenic acid affects all-cause mortality. Details: A large meta-analysis of prospective, observational studies has found that high dietary intake of alpha-linolenic acid is associated with a 10% reduced risk of all-cause mortality when compared with low dietary intake of alpha-linolenic acid. A dose-response analysis shows that a 1-gram increase in daily dietary intake is associated with a 5% reduction in overall mortality (106661). However, a meta-analysis of 250,000 individuals did not find an association between dietary alpha-linolenic acid intake and all-cause mortality (107741). The validity of this finding is limited by the use of dietary surveys to assess intake and the heterogeneity of the included studies.
• Prostate cancer. There is contradictory evidence about the role of alpha-linolenic acid in prostate cancer. Details: Some epidemiologic research suggests that high dietary intake of alpha-linolenic acid is associated with an increased risk for prostate cancer (1337,2558,7823,7147,12978). Other research suggests high intake or serum levels of alpha-linolenic acid is not associated with increased levels of prostate specific antigen (PSA) or the overall risk of prostate cancer (12961,15736,91402). However, it might increase the risk of advanced prostate cancer (12961). The best evidence to date, which comes from a meta-analysis of five prospective population studies, suggests that increasing intake of alpha-linolenic acid by 0.5 grams daily is associated with a modest 1% reduction in the risk of prostate cancer. However, this analysis is dominated by a single study. A meta-analysis of results from nine prospective population studies suggests that a 0.1% increase in blood levels of alpha-linolenic acid is not associated with prostate cancer risk (90677). Reasons for the discrepancies are not entirely clear, but the source of alpha-linolenic acid appears to be important. Alpha-linolenic acid from dairy and meat sources has been positively associated with prostate cancer. Alpha-linolenic acid from plant sources, such as flaxseed, may not affect prostate cancer risk (12909).
• Pneumonia. It is unclear if dietary alpha-linolenic acid reduces the risk for pneumonia. Details: Epidemiological research has found that increasing dietary alpha-linolenic acid consumption is associated with a reduced risk of community-acquired pneumonia (13760).
• Psoriasis. Although there is interest in using oral alpha-linolenic acid (ALA) for psoriasis, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Respiratory tract infections. It is unclear if oral alpha-linolenic acid is beneficial for reducing the incidence of respiratory tract infections in children. Details: Preliminary clinical research in children aged 3-4 years shows that taking alpha-linolenic acid 855 mg, in combination with linoleic acid 596 mg daily from November through February in 2 consecutive years, might reduce the number of recurrent respiratory infections when compared with placebo (10785).
• Rheumatoid arthritis (RA). It is unclear if oral alpha-linolenic acid is beneficial in patients with RA. Details: Preliminary clinical research shows that taking an alpha-linolenic acid-rich oil (flaxseed oil) for 3 months does not improve symptoms or laboratory parameters of RA when compared with baseline or with a linoleic acid-rich oil (safflower oil) (5898).
• Systemic lupus erythematosus (SLE). Although there is interest in using oral alpha-linolenic acid (ALA) for SLE, there is insufficient reliable information about the clinical effects of ALA for this condition.
• Ulcerative colitis. Although there is interest in using oral alpha-linolenic acid (ALA) for ulcerative colitis, there is insufficient reliable information about the clinical effects of ALA for this condition. More evidence is needed to rate alpha-linolenic acid for these uses.

(Read more about ALPHA-LINOLENIC ACID (ALA))

POSSIBLY EFFECTIVE

• Hypertension. Oral CLA seems to modestly reduce blood pressure when used along with ramipril. However, oral CLA alone does not seem to reduce blood pressure. Details: A meta-analysis of small clinical trials shows that taking CLA in doses of 1 gram to 10.8 grams daily does not lower systolic or diastolic blood pressure when compared with placebo or a control diet (111053). However, this analysis is limited by the heterogeneous populations in the individual studies. Only one study was specifically conducted in individuals with hypertension (45569). This small clinical trial in individuals with stage one uncontrolled hypertension shows that taking CLA 4.5 grams daily along with ramipril 37.5 mg daily for 8 weeks modestly reduces systolic and diastolic blood pressure when compared with ramipril alone (45569).
• Obesity. In adults and children, oral CLA seems to decrease fat mass by a small amount, including abdominal fat mass. However, it is unclear if oral CLA is beneficial for weight loss, body mass index (BMI) reduction, or improvement of metabolic measures. Details: Taking CLA 3-6.8 grams daily seems to decrease body fat mass, increase lean body mass, and reduce waist and hip circumference in some patients (2819,3153,4947,13137,45295,45303,45685,45799,97003,105809). A meta-analysis of clinical research in adults with overweight or obesity also undergoing an exercise program shows a small effect on body fat reduction, but not body weight or plasma lipids (111056). Most research suggests that doses greater than 3.4 grams daily do not seem to offer any additional benefit when compared with lower doses (2819,2821,3153,4947,10410,11327,13137,45295,45799). Also, supplementing milk with CLA 3 grams daily seems to reduce total fat mass in individuals with overweight when compared with placebo (45331). CLA also seems to reduce hunger and improve satiety and feelings of fullness, but this appetite suppression does not necessarily result in a lower energy intake or improved body weight maintenance (11327). In children with overweight aged 6-10 years, taking CLA 3 grams daily for approximately 7 months seems to reduce body fat, abdominal fat, and peripheral fat percentages when compared with placebo (45713). There is inconsistent evidence regarding the effects of CLA on body weight and BMI, with most research suggesting that CLA does not reduce total body weight or BMI (2819,2821,3153,10410,13137,45007,45679,45790,97003,97006). Also, taking CLA in combination with omega-3 fatty acids or chromium picolinate does not seem to improve BMI and body weight in individuals with overweight or obesity (42627,45431). Although one meta-analysis of clinical research shows that taking CLA 2.4-6 grams daily for 6-12 months increases weight loss by 0.7 kg and fat loss by 1.3 kg when compared with placebo, this effect is small and may not be clinically significant (91585). Also, taking CLA 3.4 grams daily for 1 year does not seem to prevent weight or body fat regain in individuals with overweight who previously lost some of their initial body weight (45083,45221). However, one study shows that taking CLA 8 grams daily for 16 weeks seems to reduce BMI in obese, postmenopausal adults with type 2 diabetes (45614). Some studies have evaluated the consumption of CLA-enriched fatty foods. In males with overweight, consuming butter enriched with CLA does not seem to have beneficial metabolic effects (45192). Also, in individuals with overweight or obesity, consuming a goat cheese naturally enriched in CLA and omega-3 fatty acids for 12 weeks does not seem to improve BMI, fat mass, or weight, or most metabolic measures, including fasting glucose, blood pressure, or inflammatory factors, when compared to a control goat cheese. However, there was an increase in total cholesterol, possibly related to an increase in high-density lipoprotein (HDL) cholesterol, and reduced levels of C-reactive protein (CRP) (105808). There is evidence that the isolated trans-10,cis-12 isomer of CLA can increase hyperproinsulinemia and insulin resistance in patients with abdominal obesity (2821,13026,13137). Hyperproinsulinemia is an independent risk factor for type 2 diabetes and cardiovascular disease. Therefore, CLA might not be a good choice for obese patients. However, most commercial CLA products contain a mixture of CLA isomers. It is not known if these mixed CLA isomer products carry this risk. One meta-analysis of clinical research shows that insulin resistance is modestly reduced when a CLA supplement is taken by adults undergoing an exercise program when compared with exercise alone (111056).

POSSIBLY INEFFECTIVE

• Common cold. Oral CLA does not seem to be beneficial for common cold prevention or treatment. Details: Some clinical research shows that taking CLA 2 grams daily does not reduce the risk of developing a cold or reduce cough or sore throat severity in individuals with a common cold when compared with placebo (45577).
• Diabetes. Oral CLA does not seem to be beneficial for diabetes. Details: Some clinical research shows that taking CLA 6.4 grams daily for 16 weeks does not improve fasting glucose, postprandial glucose, or insulin in individuals with type 2 diabetes when compared with safflower oil (45614,45835).
• Hyperlipidemia. Oral CLA does not seem to be beneficial for hyperlipidemia. Details: A meta-analysis and individual clinical trials show that taking CLA as supplements or fortified foods does not improve levels of cholesterol or triglycerides (45790,97006,111054). One meta-analysis of small clinical trials in heterogenous populations shows that taking CLA does not improve levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, or triglycerides, and modestly DECREASES levels of high-density lipoprotein (HDL) cholesterol, when compared with taking placebo or a control diet (111054). CLA has generally been taken in doses of 1.4 to 6.8 grams daily for up to 24 weeks (45790,97006,111054). However, research in patients with hyperlipidemia is limited. Most studies have included general populations of healthy adults, patient with type 2 diabetes, or populations with obesity.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). It is unclear if oral CLA is beneficial for reducing symptoms of allergic rhinitis. Details: Clinical research shows that taking CLA 2 grams daily for 12 weeks improves overall well-being in patients with birch pollen allergy when compared with placebo, but does not improve eye or total allergy symptoms (45395).
• Asthma. It is unclear if oral CLA is beneficial for reducing symptoms of asthma. Details: A small clinical trial in patients with mild asthma shows that taking CLA 4.5 grams daily for 12 weeks improves airway hypersensitivity and tolerance to strenuous exercise when compared with placebo, but without significantly reducing the need to use rescue bronchodilators or improving lung capacity (45787). In addition, a small clinical trial in children 6-18 years of age with allergic asthma shows that taking CLA 3 grams daily for 12 weeks does not reduce the use of emergency bronchodilators or improve peak expiratory flow, forced expiratory volume (FEV1), or vital lung capacity when compared with placebo (97005).
• Atherosclerosis. Although there is interest in using oral CLA for preventing atherosclerosis, there is insufficient reliable information about the clinical effects of CLA for this purpose.
• Athletic performance. It is unclear if oral CLA is beneficial for improving athletic performance. Details: Some preliminary clinical research in student athletes shows that taking CLA powder (CLAce Powder, The Nisshin OilliO Group, Ltd.) 900 mg daily for 14 days increases time to exhaustion during exercise by an average of 179 seconds, but does not reduce rate of perceived exertion, when compared with placebo (97002). Other small clinical trials show that taking a specific product containing CLA oil (Clarinol A-80, Stepan Specialty Products, LLC) 5.63 grams daily for 6 weeks in combination with aerobic training does not improve muscle endurance, muscle power, peak oxygen uptake, or cardiorespiratory fatigue threshold when compared with placebo in untrained to moderately trained males (91587,91588).
• Breast cancer. It is unclear if dietary CLA is beneficial for preventing breast cancer. Details: Some observational research has found that a higher intake of CLA in foods, particularly cheese, is linked with a lower risk of developing breast cancer in postmenopausal individuals (5058). However, other population research has found that intake of CLA is not associated with a reduced risk of breast cancer (45609). Furthermore, some epidemiological evidence has found that CLA intake might be weakly associated with an increased risk of breast cancer (45048).
• Cognitive function. It is unclear if oral CLA is beneficial for improving cognitive function in older adults. Details: Preliminary clinical research in older adults shows that taking CLA 1.75 grams twice daily for 6 weeks may modestly improve verbal learning and recall in males, but not females, when compared with placebo (97008).
• Colorectal cancer. It is unclear if dietary CLA is beneficial for preventing colorectal cancer. Details: Epidemiological research has found that high dietary intake of CLA might reduce the risk of colorectal cancer in females by up to 39% (13775). It is not known if taking CLA supplements is associated with a reduced risk of colorectal cancer.
• Metabolic syndrome. It is unclear if oral CLA is beneficial for metabolic syndrome. Details: Evidence from a small clinical trial shows that taking CLA 3 grams daily orally for 90 days, along with a hypocaloric diet, decreases body fat mass by approximately 3% when compared to baseline in females with metabolic syndrome. However, this reduction does not appear to be significant when compared with placebo treatment, and CLA does not lower blood lipid levels or blood pressure (91586).
• Muscle strength. It is unclear if oral CLA is beneficial for increasing muscle strength. Details: Some preliminary clinical research shows that adding CLA 6 grams to supplementation with creatine 9 grams and whey protein 36 grams daily for 12 weeks modestly enhances strength improvement and lean tissue mass when compared with placebo in adults participating in strength training (45596). However, other clinical research shows that taking CLA 5 grams daily for 7 weeks does not improve most measures of strength in adults participating in resistance training when compared with placebo, although bench press strength was modestly improved in males, and lean tissue mass and fat mass were also improved (45222). Other clinical research shows that taking CLA 6 grams daily for 4 weeks does not improve body composition or strength in resistance-trained athletes (45041). The reasons for these discrepancies are unclear, but may be related to the duration of treatment.
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral CLA is beneficial for NAFLD. Details: Preliminary clinical research shows that taking CLA (Nutrifit, Nutricentury) 1 gram three times daily in conjunction with a weight loss diet for 8 weeks reduces fat mass, low-density lipoprotein (LDL) cholesterol levels, and alanine aminotransferase (ALT) levels and increases muscle mass when compared with a weight loss diet alone in obese adults with NAFLD. CLA was also associated with a reduction in glycated hemoglobin, but with no corresponding reduction in fasting plasma glucose (97004).
• Physical performance. It is unclear if oral CLA is beneficial for improving physical performance in older adults. Details: Preliminary clinical research in adults 65-85 years of age shows that taking CLA 1.75 grams twice daily for 6 weeks does not improve handgrip strength or hand discomfort when compared with placebo (97008).
• Rheumatoid arthritis (RA). It is unclear if oral CLA is beneficial for RA. Details: Preliminary clinical research shows that taking CLA 2.5 grams daily with or without vitamin E 400 mg daily for 12 weeks reduces pain and morning stiffness and reduces erythrocyte sedimentation rate in patients with RA when compared to baseline (45730). The validity of these findings is limited by the lack of a comparator group. More evidence is needed to rate conjugated linoleic acid for these uses.

(Read more about CONJUGATED LINOLEIC ACID (CLA))

POSSIBLY INEFFECTIVE

• Bipolar disorder. Oral flaxseed oil does not seem to reduce symptoms of bipolar disorder in children. Details: Clinical research in children ages 6-17 years with bipolar disorder shows that taking flaxseed oil, titrated to provide up to 6.5 grams of the flaxseed oil constituent alpha-linolenic acid, daily for 16 weeks does not improve symptoms of mania or depression when compared with placebo (66044).
• Hyperlipidemia. Oral flaxseed oil does not seem to reduce cholesterol levels. Details: Although some evidence from preliminary, low-quality clinical studies disagrees (21698,26466,76696), most clinical research shows that taking flaxseed oil does not reduce cholesterol or triglyceride levels in patients with or without hypercholesterolemia or hypertriglyceridemia (2317,16791,16794,21693,21694,21696,21697,22177,72228,101947)(101954,101956,111062). A meta-analysis of clinical studies evaluating various flaxseed formulations suggests that flaxseed oil consumption may reduce apolipoprotein A levels, but not apolipoprotein B levels, when compared with control groups (108046). A subgroup analysis from another meta-analysis suggests that flaxseed oil may modestly improve levels of high-density lipoprotein cholesterol (108044). It should be noted that most research suggests that flaxseed, the source of flaxseed oil, can improve lipid levels in adults with hyperlipidemia. This difference may be due to lipid lowering components such as lignans, phytic acid, and polyphenols, that are found in flaxseed, but not flaxseed oil. See the Flaxseed monograph for more information.
• Obesity. Oral flaxseed oil does not seem to improve weight loss. Details: A meta-analysis of clinical research in overweight adults shows that flaxseed oil consumption does not reduce body weight, body mass index, or waist circumference when compared with control (96427). This is in contrast to research suggesting that flaxseed, the source of flaxseed oil, can improve weight loss in obese and overweight adults. See the Flaxseed monograph for more information.
• Rheumatoid arthritis (RA). Oral flaxseed oil does not seem to improve symptoms of RA. Details: A small clinical study in patients with RA shows that taking flaxseed oil daily for 3 months does not seem to improve symptoms of pain and stiffness, and has no effect on laboratory measures of RA, such as C-reactive protein and erythrocyte sedimentation rate (ESR), when compared with control (5898).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Atherosclerosis. Small clinical trials show that taking flaxseed oil has modest benefit on metabolic risk factors in patients with plaque in the coronary artery. Details: Observational research in White adults has found that high dietary intake of linolenic acid, a flaxseed oil constituent, is associated with reduced calcified atherosclerotic plaque in the coronary arteries (12990). However, clinical research has not confirmed this finding. A small clinical trial in patients with coronary artery disease shows that taking flaxseed oil 5 grams in milk containing 1.5% fat reduces triglyceride levels by 14% when compared with the milk alone. However, there was no effect on systolic blood pressure, high-density lipoprotein (HDL) cholesterol, or low-density lipoprotein (LDL) cholesterol (101954). Additionally, another small study in a similar patient population shows that taking flaxseed oil 2 grams daily for 12 weeks has no effect on lipid levels when compared with placebo (101956).
• Attention deficit-hyperactivity disorder (ADHD). Oral flaxseed oil has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical trial in children with ADHD shows that taking flaxseed oil, providing 200 mg of alpha-linolenic acid, in combination with vitamin C 25 mg, twice daily can improve measures of attention, impulsivity, restlessness, and self-control when compared to baseline (14443). This finding is limited by the lack of a control group. Furthermore, it is unclear if the benefit is due to flaxseed oil, vitamin C, or the combination.
• Breast cancer. It is unclear if oral flaxseed oil reduces the risk of breast cancer. Details: Population research has found that females with higher levels of the flaxseed oil constituent, alpha-linolenic acid (ALA), in breast adipose tissue have a lower risk of breast cancer. Fatty acid composition of adipose tissue is thought to reflect past dietary intake, so researchers think high intake of ALA might have a cancer protective effect (7168,21689). Flaxseed oil is one source of ALA; it is unclear what effect, if any, flaxseed oil has on breast cancer risk.
• Burns. It is unclear if oral flaxseed oil improves wound healing and health in people with burns. Details: A small clinical trial in patients with mild to moderate burns shows that eating cookies containing flaxseed oil 30 grams and isolated soy protein (ISP) 50 grams daily for 3 weeks improves the rate of wound healing when compared with control cookies. It seems to take at least 3 weeks before this difference is observed. However, there is no significant difference in the rate of wound healing when compared with cookies containing ISP with corn oil (99401). It is possible that the study was underpowered to detect a difference between these two groups.
• Cardiovascular disease (CVD). It is unclear if oral flaxseed oil reduces the risk of CVD. Details: Flaxseed oil is a source of alpha-linolenic acid (ALA). A meta-analysis of observational studies has found that, overall, increasing dietary intake of ALA by 1.2 grams daily is associated with a 20% reduced risk of fatal coronary heart disease in people with existing heart disease (12978). Some research suggests that ALA has a greater impact on coronary heart disease when intake of fish oils is low (12989). It is unknown if flaxseed oil supplements have these same effects. Additionally, it is difficult to separate effects of dietary ALA in these studies from those of other dietary, lifestyle, or drug interventions (12917).
• Carpal tunnel syndrome. It is unclear if topical flaxseed oil reduces carpal tunnel pain. Details: Preliminary clinical research in patients with carpal tunnel syndrome who wear a wrist splint at night shows that applying flaxseed oil 5 drops topically on the palmar wrist twice daily for 4 weeks improves subjective symptom scores by 30%, function scores by 17%, and sensory nerve conduction velocity of the median nerve by about 7% when compared to baseline. Compared to the changes observed for patients in the placebo group, these improvements were significant (25691). It is unclear if this benefit persists long-term or how topical flaxseed oil compares to other standard treatments for carpal tunnel syndrome.
• Chronic kidney disease (CKD). Although there is interest in using oral flaxseed oil for CKD, there is insufficient reliable information about the clinical effects of flaxseed for this condition.
• Cognitive function. It is unclear if oral flaxseed oil improves cognitive function in healthy adults. Details: Clinical research in healthy older Japanese adults with normal cognitive function shows that taking flaxseed oil 3.7 grams daily for 12 weeks modestly improves verbal fluency when compared with taking placebo. However, there was no effect on other measures of cognitive function, including attention, concentration, and memory (111060).
• Diabetes. Oral flaxseed oil may not improve glycemic control in patients with type 2 diabetes. However, there may be some benefit in patients with gestational diabetes. Details: Most clinical research in patients with type 2 diabetes shows that taking flaxseed oil, providing about 1-16 grams of alpha-linolenic acid, daily for up to 6 months does not improve fasting blood glucose, glycated hemoglobin (HbA1C), or insulin resistance when compared with placebo (16792,66065,96428,96431,101956,111062). While taking flaxseed oil does not seem to be beneficial for type 2 diabetes, it might improve outcomes in gestational diabetes. A small clinical study in pregnant patients (24-28 weeks gestation) with gestational diabetes shows that taking flaxseed oil 1 gram twice daily for 6 weeks reduces fasting levels of glucose and insulin and improves insulin resistance when compared with placebo (101957). Another small clinical study in patients with gestational diabetes shows that taking flaxseed oil 1 gram, containing 400 mg of alpha-linolenic acid, along with vitamin E 400 IU daily for 6 weeks reduces blood glucose levels, insulin levels, and insulin resistance and improves beta-cell function when compared with placebo (96432). It is unclear if the findings from this latter study are due to flaxseed oil, vitamin E, or the combination.
• Diabetic foot ulcers. It is unclear if oral flaxseed oil improves the healing of diabetic foot ulcers. Details: One small clinical trial in adults with grade 3 diabetic foot ulcers shows that taking flaxseed oil 1 gram twice daily for 12 weeks in conjunction with intravenous antibiotics for the first 3 weeks reduces ulcer size when compared with placebo (96431).
• Dry eye. Flaxseed oil, both orally and as an eye drop, has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical study in patients with dry eye shows that taking a specific combination product (TheraTears Nutrition, Advanced Vision Research) containing eicosapentaenoic acid 450 mg, docosahexaenoic acid 300 mg, and flaxseed oil 1000 mg daily for 90 days reduces subjective symptoms of dry eye and might increase tear production when compared with placebo. However, it did not improve meibomian gland secretions or tear evaporation rate when compared with placebo (17523). Eye drops with flaxseed oil have also been tried for dry eye. A clinical study shows that using a specific product (Refresh Optive MEGA-3 Preservative-Free Lubricant Eye Drops, Allergan plc) which contains flaxseed oil and trehalose in addition to other ingredients such as carboxymethylcellulose (CMC) and castor oil twice daily for 90 days improves dry eye symptoms when compared to baseline, but not when compared with the same eye drops formulated without flaxseed oil and trehalose (101953).
• Dry skin. There is conflicting evidence regarding the use of flaxseed oil for dry skin. Details: Some clinical research suggests that taking flaxseed oil 2.2 grams orally in combination with alpha-tocopherol 10 mg daily for 12 weeks does not improve skin hydration when compared with placebo or borage oil in females with dry skin, although the combination seems to improve the sensitivity of dry skin (21908). Other clinical research suggests that taking flaxseed oil 2.2 grams daily for 12 weeks improves skin hydration and roughness when compared with safflower oil (21909).
• Endometrial hyperplasia. It is unclear if oral flaxseed oil reduces endometrial hyperplasia. Details: A small clinical trial in adults with endometrial hyperplasia shows that taking flaxseed oil 1 gram twice daily for 12 weeks does not induce endometrial regression or reduce cholesterol levels when compared with placebo. However, there appears to be a small benefit on fasting plasma glucose and insulin levels (101955).
• Hypertension. Small studies suggest that flaxseed oil may modestly lower blood pressure in some patients. Details: Epidemiological research has found that high dietary intake of linolenic acid, a flaxseed oil constituent, is associated with a reduced risk of developing hypertension (12991). Meta-analyses of small clinical studies in patients with and without hypertension show that receiving flaxseed oil 1.2-30 grams daily for 4-24 weeks reduces systolic and diastolic blood pressure by 0.5 mmHg to 4 mmHg, when compared with control (96426,111063). One meta-analysis limited to small clinical trials in patients with metabolic syndrome, hypercholesterolemia, or hypertension, shows that taking flaxseed oil 25 mL or 2.2 to 9.2 grams daily for 7-12 weeks reduces systolic blood pressure by about 3.9 mmHg; however, there is no effect on diastolic blood pressure (111067). The small size and heterogeneity of the studies included in these meta-analysis limit the validity of these findings. Also, the effect of taking flaxseed oil in patients specifically with hypertension is unclear from this available research. Flaxseed oil has also been evaluated in combination with other oils and dietary interventions, with mixed evidence of benefit. Flaxseed oil 19 grams, providing 10.5 grams of alpha-linolenic acid, seems to reduce blood pressure when combined with walnuts and walnut oil daily for 6 weeks (21905). However, consuming 60 grams of a combination of flaxseed and safflower oils in a 6:4 ratio daily for 4 weeks does not seem to affect blood pressure when compared with baseline (26466).
• Mastalgia. It is unclear if oral flaxseed oil is beneficial in patients with mastalgia. Details: A clinical study in adults with fibrocystic breasts and mastalgia shows that taking flaxseed oil 1000 mg containing 350 mg alpha-linolenic acid twice daily for 2 months reduces pain when compared with baseline, but is no different than taking vitamin E 200 IU daily (105477).
• Metabolic syndrome. It is unclear if oral flaxseed oil is beneficial in patients with metabolic syndrome. Details: A small clinical study in patients with metabolic syndrome shows that taking flaxseed oil 20 mL daily for 7 weeks does not improve coagulation scores based on prothrombin time, partial thromboplastin time, and the international normalized ratio (INR) when compared with sunflower oil (101951).
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral flaxseed oil is beneficial in patients with NAFLD. Details: Clinical research in overweight or obese patients with NAFLD shows that taking flaxseed oil 20 grams daily for 12 weeks as part of a hypocaloric diet improves the grade of fatty liver by 41%, compared with 18% in patients taking sunflower oil. There was also a small effect on body mass index, although there was no effect on liver enzymes, glycemic control, or body composition (101952).
• Parkinson disease. Oral flaxseed oil has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One small clinical study in patients with Parkinson disease shows that taking flaxseed oil 1 gram daily plus vitamin E 400 IU daily for 12 weeks improves the Unified Parkinson Disease Rating Scale (UPDRS) total score by 3.3 points, compared to a 4.4-point worsening in the placebo group (96430). However, it is unclear if this change is clinically meaningful. The minimal clinically important improvement in UPDRS total score is 4.3 points, while a moderate improvement ranges from 9 to 17 points (95686). Also, it is not clear if these findings are due to flaxseed oil, vitamin E, or the combination.
• Physical performance. It is unclear if oral flaxseed oil improves physical performance in older adults. Details: A small clinical study in elderly adults without previous exercise training suggests that flaxseed oil containing alpha-linolenic acid does not improve muscle strength when compared with placebo (65937).
• Pneumonia. It is unclear if oral flaxseed oil helps to prevent pneumonia. Details: Epidemiological research has found that increasing dietary alpha-linolenic acid, which occurs in flaxseed oil, is associated with a reduced risk of community-acquired pneumonia (13760). However, this research did not specifically assess the effect of flaxseed oil intake on pneumonia.
• Polycystic ovary syndrome (PCOS). Small clinical studies suggest that oral flaxseed oil might help to improve some markers of PCOS. Details: A small clinical study in patients with PCOS shows that taking flaxseed oil, providing 545 mg of alpha-linolenic acid, for 6 weeks lowers triglycerides but does not affect weight, hormone levels, glycemic control, or cholesterol levels when compared to baseline (21906). This finding is limited by the lack of a control group. Another small clinical study in patients with PCOS shows that taking flaxseed oil, providing 1 gram of omega-3 fatty acids, twice daily in addition to metformin for 12 weeks decreases triglyceride and insulin levels, but does not affect fasting blood glucose, testosterone levels, free androgen index, or total cholesterol when compared with placebo (99402).
• Prostate cancer. Oral flaxseed oil does not seem to be linked to prostate cancer risk. Details: Although some epidemiologic research has found that high dietary intake of alpha-linolenic acid, a constituent of flaxseed oil, is associated with an increased risk for prostate cancer (1334,1337,2558,7823,7147,12978,12961), other research has found no association (12961,15736). Furthermore, it appears that alpha-linolenic acid from plant sources, such as flaxseed or flaxseed oil, does not increase prostate cancer risk (12909).
• Ulcerative colitis. It is unclear if oral flaxseed oil is beneficial in patients with ulcerative colitis. Details: A small open-label clinical study in patients with ulcerative colitis shows that taking flaxseed oil 10 grams daily for 12 weeks seems to modestly reduce inflammatory markers and disease severity and improve quality of life when compared with control (101941). More evidence is needed to rate flaxseed oil for these uses.

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POSSIBLY EFFECTIVE

• Coronary heart disease (CHD). Supporting, but not conclusive, evidence suggests that consuming fats and oils rich in oleic acid might reduce the risk of CHD (26466,95745,98563,101821). However, the relationship between blood levels of oleic acid and risk of CHD or CVD is unclear (101832,101834,101838). In 2018, the US Food and Drug Administration (FDA) determined that it would allow a qualified health claim stating that replacing dietary fats and oils higher in saturated fat with oils containing at least 70% oleic acid may reduce the risk of CHD. To achieve this benefit, high-oleic acid containing oils should not increase total daily energy intake. The suggested daily dietary intake is about 20 grams (1.5 tablespoons) of high oleic acid oils in place of other fats and oils. These oils include olive oil, high-oleic acid sunflower oil, and high-oleic acid canola oil (98563). A meta-analysis of clinical studies shows that replacing 7.5% of energy from partially hydrogenated vegetable oils with high oleic acid sunflower oil can reduce coronary heart disease risk by about 9% to 19%. Furthermore, analysis of results from observational studies found that replacing partially hydrogenated oil with high oleic acid sunflower oil is associated with a 16% to 35% reduction in the risk of coronary heart disease events (95745). Clinical research in patients with cardiovascular disease (CVD) risk shows that taking high-oleic acid canola oil 60 grams per 3000 kcal of energy daily as part of a fixed composition diet for 4-6 weeks reduces the Framingham 10-year coronary heart disease risk scores by 6.8% compared to baseline (26466,101821). However, taking the high-oleic acid canola oil is no more effective than regular canola oil, which contains approximately 62% oleic acid (26466,101821). The relationship between blood levels of oleic acid and risk of CHD or CVD is unclear. While some population research has found that having the highest blood levels of oleic acid is associated with an increased risk of CVD when compared to having the lowest blood levels of oleic acid, other research suggests an inverse association or no association at all (101832,101834,101838). One study has found that having the highest blood levels of oleic acid is associated with a 1.4- to 2-fold increased risk of heart failure, other cardiovascular events, and all-cause mortality (101832). In contrast, another found that the highest blood levels of oleic acid is associated with a 73% reduced risk of having a stroke (101838). A third study found no association at all between plasma levels of oleic acid and risk of heart failure (101834). The clinical significance of these findings is unclear, and results should not necessarily be extrapolated to dietary oleic acid (101832). While plasma oleic acid levels seem to be a weak indirect marker of moderate to high olive oil use, it is also a weak marker of intake of butter and avian fats (101838). Furthermore, there is no clear evidence that plasma levels of oleic acid directly correlate with dietary oleic acid, especially where dietary oleic acid intake is relatively low (101832). As a non-essential fatty acid, oleic acid is endogenously synthesized in the liver from saturated fats (101832,101834,101838).
• Hypercholesterolemia. Evidence from small studies shows that consuming oils rich in oleic acid as part of the diet in place of other dietary fats may improve cholesterol levels (21698,26466,67569,101821). Preliminary clinical research in patients with hypercholesterolemia shows that consuming oleic acid as part of a high oleic sunflower oil- or high oleic canola oil-rich diet for 3-4 weeks decreases total and low-density lipoprotein (LDL) cholesterol levels by a moderate amount when compared with diets rich in palm oil, medium-chain triglycerides, or a blend of fats found in a regular Western diet (21698,67569). Other clinical research in patients with at least one cardiovascular risk factor shows that consuming oleic acid as part of high oleic acid canola oil for up to 4 weeks reduces total cholesterol by up to 9.4% and LDL cholesterol by up to 12.5% compared to baseline or a diet higher in saturated fats. However, taking the high oleic acid canola oil is no more effective than regular canola oil, also a source of oleic acid (26466,101821).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Bladder cancer. Population research has found that the highest blood levels of oleic acid are associated with a 46% decreased risk of having bladder cancer when compared to the lowest blood levels (101844). However, plasma oleic acid levels are only a weak indirect marker of dietary intake of oleic acid. As a non-essential fatty acid, oleic acid is endogenously synthesized in the liver from saturated fats (101832,101834,101838). The effect of oleic acid supplementation on bladder cancer risk is unknown.
• Breast cancer. Population research has found no association between dietary fatty acid intake, including oleic acid, and the risk of breast cancer (96528). The effect of oleic acid supplementation on breast cancer risk is unknown.
• Depression. An observational study in perimenopausal patients aged 42-52 years has found that increasing dietary intake of oleic acid is associated with an increase in depression symptom scores. The odds ratio for depressive symptoms was approximately 2-fold higher for the highest quartile of oleic acid intake when compared with the lowest quartile (108924).
• Diabetes. A small clinical trial in patients with type 2 diabetes shows that taking oleic acid as part of a low-fat diet containing 15% monounsaturated fatty acids for 3 weeks does not alter levels of total or low-density lipoprotein (LDL) cholesterol or the change in LDL oxidation when compared with taking linoleic acid as part of a low-fat diet containing 15% polyunsaturated fatty acids (101847).
• Diarrhea. Preliminary clinical research in patients with chronic diarrhea shows that taking oleic acid 1.6 or 3.2 mL before a meal reduces bowel movements over the next 24 hours by approximately 22% compared with taking no oleic acid. Intestinal transit time was also increased by 28 and 54 minutes, respectively (101848). Since the specific cause of chronic diarrhea differed among the patients included in this study, it is unclear if oleic acid is beneficial for most or only certain forms of chronic diarrhea.
• Hypertension. Preliminary clinical research in patients with central obesity and at least one other cardiovascular disease risk factor shows that taking oleic acid as high oleic acid canola oil for 4 weeks does not reduce systolic or diastolic blood pressure compared to baseline (26466).
• Obesity. Preliminary clinical research in patients with central obesity shows that taking oleic acid as high oleic acid canola oil for 4 weeks reduces abdominal fat mass by approximately 0.1 kg compared to baseline (98564). Other preliminary clinical research in patients with central adiposity and at least one other risk factor of cardiovascular disease shows that taking high oleic acid canola oil for 6 weeks reduces total and low-density lipoprotein (LDL) cholesterol by 3.4% and 5.6%, respectively, compared with a control oil lower in monounsaturated fats and higher in saturated fats (101821). However, in these studies, taking the high oleic acid canola oil is no more effective than regular canola oil, also a source of oleic acid (98564,101821). Any effect of oleic acid itself is unclear.
• Pancreatic cancer. The association between dietary oleic acid and pancreatic cancer risk is unclear. Most population research shows no association between dietary oleic acid and pancreatic cancer risk. However, one large population study has found that the highest intake of oleic acid, at least 23.7 grams daily, is associated with a 71% decreased risk of pancreatic cancer when compared with the lowest intake. The benefit is only observed in overweight or obese individuals. (101833). The effect of oleic acid supplementation on pancreatic cancer risk is unknown.
• Short bowel syndrome. A small preliminary clinical trial in patients with surgical short bowel syndrome of at least 2 years shows that taking oleic acid 3.2 mL in 50 mL of a beverage daily for 3 months does not reduce intestinal transit time or diarrhea, or improve body weight, when compared with placebo. In addition, energy absorption was reduced by 14% (101843).
• Stroke. Population research has found that highest blood levels of oleic acid are associated with a 73% reduced risk of stroke when compared with lowest blood levels of oleic acid (101838). However, plasma oleic acid levels are only a weak indirect marker of dietary oleic acid. As a non-essential fatty acid, oleic acid is endogenously synthesized in the liver from saturated fats (101832,101834,101838). The effect of oleic acid supplementation on stroke risk is unknown.
• Ulcerative colitis. Although some contradictory evidence exists, a large population study has found that, after adjusting for dietary intake of omega-3 fatty acids, highest dietary intake of oleic acid is associated with a 97% reduced odds of developing ulcerative colitis when compared with the lowest intake (101846). The effect of oleic acid supplementation on ulcerative colitis risk is unknown.

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LIKELY SAFE ...when used orally in amounts typically found in foods (7141,7142,7144). There is insufficient reliable information available about the safety of alpha-linolenic acid when used in larger, medicinal amounts.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts typically found in foods (7141,7142,7145). There is insufficient reliable information available about the safety of alpha-linolenic acid during pregnancy and lactation when used in larger, medicinal amounts; avoid using.

(Read more about ALPHA-LINOLENIC ACID (ALA))

LIKELY SAFE ...when used orally in amounts found in foods. CLA occurs naturally in milk fat, beef, and the meat of other ruminant animals (5924,5925,5932,5933).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts of up to 6. 8 grams daily, short-term (2819,2821,3153,4947,10410,11327,111056).

CHILDREN: LIKELY SAFE
when used orally in amounts found in foods. CLA occurs naturally in milk fat, beef, and the meat of other ruminant animals (5924,5925,5932,5933).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately in medicinal amounts. Some evidence suggests that CLA 3 grams daily can be taken safely for up to 7 months (45713).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts found in foods (5924,5932,5933). There is insufficient reliable information available about the safety of CLA when used in medicinal amounts during pregnancy or lactation; avoid using.

(Read more about CONJUGATED LINOLEIC ACID (CLA))

LIKELY SAFE ...when used orally and appropriately for medicinal purposes, short-term. Flaxseed oil has been used safely in doses up to 2 grams daily for up to 6 months. Higher doses of up to 24 grams daily has been safely used for up to 7 weeks (845,3912,5898,14443,16789,16791,16794,16795,17523,101951,101952,101955).

POSSIBLY SAFE ...when used topically for medicinal purposes, short-term. Flaxseed oil has been used safely on the wrist for up to 4 weeks (25691). ...when used in eye drops twice daily for up to 90 days (101953).

CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term. Some evidence suggests that flaxseed oil, providing 200 mg of alpha-linolenic acid, can be safely used in children for up to 3 months (14443).

PREGNANCY: POSSIBLY SAFE
when used orally and appropriately for medicinal purposes, short-term. Although flaxseed oil has been used with apparent safety in clinical research in doses of 1-2 grams daily for up to 6 weeks (96432,101957), some population research has found that consuming flaxseed oil during the second and third trimesters of pregnancy is associated with a four-fold increased risk of premature birth (16797).

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about FLAXSEED OIL)

LIKELY SAFE ...when used orally in food amounts. Edible oils containing high amounts of oleic acid are commonly used in foods (26466,90681,94452,101821,101824,101828,101830,101838). There is insufficient reliable information available about the safety of oleic acid when used as medicine.

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using in amounts greater than those commonly found in foods.

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(Read more about ALPHA-LINOLENIC ACID (ALA))

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, CLA may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Some clinical evidence suggests that intake of CLA reduces platelet aggregation by approximately 10% (45607). The clinical significance of this effect is unclear.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = A Theoretically, taking CLA with antihypertensive drugs might increase the risk of hypotension.  Details Animal research suggests that a particular form of CLA reduces systolic blood pressure (45081). Also, some clinical research shows that CLA enhances the blood pressure-lowering effects of ramipril, an antihypertensive drug (45569).

RAMIPRIL (ALTACE) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = A Theoretically, taking black seed with ramipril might increase the risk of hypotension.  Details Some clinical research shows that CLA enhances the blood pressure-lowering effects of ramipril (45569).

(Read more about CONJUGATED LINOLEIC ACID (CLA))

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, using flaxseed oil in combination with anticoagulant or antiplatelet drugs might have additive effects and increase the risk of bleeding.  Details Small clinical studies show that consuming flaxseed oil might decrease platelet aggregation and increase bleeding time (5898,21912).

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, combining flaxseed oil with other antihypertensive drugs might have additive effects and increase the risk of hypotension.  Details Some clinical evidence suggests that long-term consumption of flaxseed oil can modestly lower systolic and diastolic blood pressure, while other clinical research shows no effect (16793,96426,101941,101954,111063,111067).

EZETIMIBE (Zetia) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Concomitant use of flaxseed oil and ezetimibe reduces the absorption of alpha-linolenic acid from flaxseed oil.  Details In one clinical study, concomitant consumption of ezetimibe 10 mg daily with flaxseed oil 2 grams providing 1 gram of alpha-linolenic acid daily blocked the absorption of alpha-linolenic acid, resulting in an overall reduction in alpha-linolenic plasma levels from baseline (96433).

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(Read more about OLEIC ACID)

General ...Orally, alpha-linolenic acid from dietary sources is well tolerated when used in the diet as a replacement for other sources of fat, such as saturated fats.
Serious Adverse Effects (Rare):
Orally: There is some concern that high dietary intake of alpha-linolenic acid might increase the risk for prostate cancer, although research is conflicting.

Oncologic ...Epidemiologic research suggests that high dietary intake of alpha-linolenic acid might increase risk for prostate cancer (1337,2558,7823,7147,12978). Other research suggests high intake or serum levels of alpha-linolenic acid does not increase the overall risk of prostate cancer (12961,15736); however, it might increase the risk of advanced prostate cancer (12961). Association with prostate cancer appears to depend on the sources of alpha-linolenic acid. Dairy and meat sources has been positively associated with prostate cancer, whereas plant sources, such as flaxseed, don't seem to affect prostate cancer risk (12909). According to a clinical trial, intake of alpha-linolenic acid does not appear to increase levels of prostate specific antigen (PSA) (91402). Also, longer-chain omega-3 fatty acids in fish oils are associated with a decreased risk of total and advanced prostate cancer (12961).

Other ...Alpha-linolenic acid is a type of fat, containing 9 kilocalories/gram, and may result in weight gain if consumed in excess. Patients should be advised that it's best to substitute alpha-linolenic acid in the diet for other sources of fat, such as saturated fats.

(Read more about ALPHA-LINOLENIC ACID (ALA))

General ...Orally, CLA is well tolerated when found in foods. When taken in medicinal amounts, CLA seems to be well tolerated.
Most Common Adverse Effects:
Orally: Diarrhea, dyspepsia, flatulence, loose stools, and nausea.
Serious Adverse Effects (Rare) :
Orally: Cases of hepatotoxicity have been reported.

Cardiovascular ...Some preliminary clinical research suggests that the t10,c12 isomer of CLA can decrease high-density lipoprotein (HDL) cholesterol levels (2821). This isomer of CLA, as well as a mixture of CLA isomers, seems to increase plasma triglyceride levels, the ratio of low-density lipoprotein (LDL) cholesterol to HDL cholesterol, and the ratio of total cholesterol to HDL cholesterol (45148,45468), although not all research has identified these effects (107475).
A meta-analysis of 6 randomized, controlled trials shows that administration of CLA in individuals who are overweight or obese significantly increases lipoprotein (a) levels, a value associated with increased risk of cardiovascular disease. Subgroup analyses suggest this increase is more prominent in trials that are longer than 6 months in duration and with CLA doses of at least 3.5 grams daily (107475).

Endocrine ...Orally, CLA has been shown to increase insulin resistance and glucose concentrations, as well as decrease insulin sensitivity in some patients, including obese individuals or patients with type 2 diabetes (2821,13026,45145,45152,45513). Some evidence suggests that this effect is isomer-specific and occurs with only the t10,c12 isomer (2821,13026), while other evidence shows that decreased insulin sensitivity may also occur with the c9,t11 isomer or with a 50:50 mixture of c9,t11 and t10,c12 isomers (45145,45152).

Gastrointestinal ...Orally, the most common adverse effect reported with CLA is gastrointestinal upset including diarrhea, constipation, nausea, loose stools, dyspepsia, bloating, and flatulence (3153,4947,45280,45705,45730,111056). Esophageal irritation was reported in one patient who bit open and swallowed a capsule containing CLA (45577).

Hepatic ...Orally, clinical research shows that CLA 3 grams daily for 12 weeks does not affect liver outcome measures (105809). However, there are at least two case reports of hepatotoxicity. Asthenia, jaundice, and pruritus were reported in a 46-year-old female who consumed CLA for two weeks. Abnormal liver enzyme levels returned to normal following discontinuation of CLA supplementation (45483). Hepatotoxicity, presenting as fulminant hepatitis and characterized by anorexia, nausea, jaundice, choluria, and hepatic encephalopathy requiring liver transplantation has also been reported in a 63-year-old female taking a CLA-containing weight-loss supplement for one month (91589).

Musculoskeletal ...Orally, CLA has been reported to cause back ache in one individual in one clinical trial (45787).

Neurologic/CNS ...Orally, CLA may cause headache or fatigue (3153,45787). In one case report, a 50-year-old female presented with headache and subarachnoid hemorrhage due to reversible cerebral vasoconstriction syndrome (RCVS) after taking a combination product containing green tea, L-carnitine, and CLA for one week. At 28 days after discontinuation of the combination product and surgery, angiography showed complete regression of vascular restrictions (97007). It is unclear if this adverse effect was due to CLA, another ingredient in the product, or a combination of ingredients.

Other ...Orally, CLA has been reported to cause halitosis in one patient in one clinical trial (45839).

(Read more about CONJUGATED LINOLEIC ACID (CLA))

General ...Orally, flaxseed oil is generally well tolerated. Topically, flaxseed oil seems to be well-tolerated.
Most Common Adverse Effects:
Topically: Itching, redness.
Serious Adverse Effects (Rare):
Orally: Severe allergic reactions such as anaphylaxis.

Endocrine ...Orally, flaxseed oil might cause gynecomastia. In a case report, a 70-year-old male developed gynecomastia after taking flaxseed oil daily for 3 months. Discontinuing flaxseed oil lead to resolution of gynecomastia (105478).

Gastrointestinal ...Orally, flaxseed oil may cause a change in bowel habits, dry mouth, and dyspepsia when taken at a dose of about 5 grams daily. However, these effects have been reported by only a small number of patients (approximately 3%) (16794). High doses of flaxseed oil (30 grams per day and higher) have been associated with loose stools and diarrhea (5898,11025).

Immunologic ...Severe allergic reactions such as anaphylaxis have been reported with flaxseed oil ingestion and also in workers processing flaxseed products (6809).

Ocular/Otic ...Topically, eye drops containing flaxseed oil may cause redness and itching (101953).

Oncologic ...Flaxseed oil has not been linked to increased prostate cancer risk. Although epidemiologic research has found that high dietary intake of alpha-linolenic acid (ALA) is associated with increased prostate cancer risk (1337,2558,7147,7823,12978), this risk does not seem to apply to ALA from plant sources, like flaxseed (12909).

(Read more about FLAXSEED OIL)

General ...Orally, oleic acid generally well tolerated when used as part of oils and fats in the diet (26466,90681,94452,101821,101824,101828,101830,101838). Temporary burning in the mouth or throat has occurred in some patients (101848).

Gastrointestinal ...Orally, oleic acid has caused temporary burning in the mouth or throat in some patients in one clinical study (101848).

(Read more about OLEIC ACID)