Alpha-linolenic acid (ALA) is converted to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA is a precursor for the series-3 prostaglandins, the series-5 leukotrienes, and the series-3 thromboxanes.
EPA and DHA modify cell membrane fluidity and the products of EPA (prostaglandins, leukotrienes, and thromboxanes) have anti-inflammatory and anti-thrombotic activities.
The n-3 fatty acids are important for development of an infant’s brain and retina, and are thus essential during pregnancy and breastfeeding.
Lignan is metabolized by intestinal microflora to form enterolactone and enterodiol, which have phytoestrogenic activity.
Flaxseeds, ground flaxseed, crushed flaxseeds, and flaxseed oil are available. These different forms have slightly different activities, due to differences in bioavailability and content. Ground or crushed seeds have higher bioavailability than whole flaxseeds. Flaxseed oils have higher concentrations of lignans and alpha-linolenic acid, but do not contain fiber.
Patients taking anticoagulant agents, such as warfarin [Coumadinâ], may experience abnormal bleeding. Patients may benefit by starting the medication at a lower dose with concomitant ingestion of flaxseed oil, and those with a bleeding disorder should consult a physician or pharmacist before starting the therapy.
Information on the relationship between substances and disease is provided for general information, in order to convey a balanced review of the scientific literature. In many cases the relationship between a substance and a disease is tentative and additional research is needed to confirm such a relationship.
Flaxseed improves lipid profile without altering biomarkers of bone metabolism in postmenopausal women
To examine the effect of ground flaxseed on lipid metabolism and biomarkers of bone metabolism, thirty-six postmenopausal women consumed 40 grams of ground flaxseed or a placebo daily for three months along with 1000 mg calcium and 400 IU vitamin D. Women receiving hormone replacement therapy were excluded from the study. Flaxseed supplementation significantly decreased total and non HDL cholesterol concentrations by 6%. LDL and HDL cholesterol concentrations were reduced by 4.7% and reduced triglyceride concentrations by 12.8% although these reductions were not significant. These results indicate that flaxseed reduced risk factors for cardiovascular diseases, but did not alter biomarkers of bone metabolism.9
The effects of flaxseed dietary supplement on lipid profile, bone mineral density, and symptoms in menopausal women: a randomized, double-blind, placebo-controlled clinical trial
One-hundred-ninety-nine menopausal women participated in a double-blind clinical trial to assess the effects of ground flaxseed on blood lipid profiles, bone mineral density, and symptoms of menopause. Subjects consumed 40 grams/day of ground flaxseed or a placebo for 12 months. Total and HDL cholesterol decreased significantly in the ground flaxseed group compared to placebo. No changes in bone mineral density were detected. The authors concluded that ground flaxseed supplements improved blood lipid profiles, but not enough to be clinically significant.10
Flaxseed oil increases the plasma concentrations of cardioprotective (n-3) fatty acids in humans
Fifty-six chronically ill people were randomly assigned to receive either 3 grams/day of alpha-linolenic acid from flaxseed oil or an olive oil placebo for 12 weeks. Plasma concentrations of EPA increased by 60% and plasma concentrations of DPA increased by 25% after 12 weeks. No change in DHA was detected in either group. These data indicate that flaxseed oil may be a useful substitute for fish oil supplements for improving plasma concentrations of cardioprotective fatty acids.11
Topic: American Heart Association Scientific Statement
Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease
In 2002, the American Heart Association (AHA) updated its recommendations reguarding omega-3 fatty acids and cardiovascular disease. In this new statement, the benefits of omega-3 fatty acids are reviewed and flaxseeds as well as flaxseed oil are recommended to increase daily intake of alpha-linolenic acid. Thus, the AHA concluded that the current scientific data support including fish, fish oil, and omega-3 fatty acids from sources such as flaxseeds to reduce risk for cardiovascular disease.12
Supplementation with flaxseed oil versus sunflower seed oil in healthy young men consuming a low fat diet: effects on platelet composition and function
Eleven healthy young subjects were given either flaxseed oil (40 g/day) or sunflower seed oil for 23 days and platelet aggregation was measured. Platelets from the flaxseed oil group were rich in EPA, compared to the control group. Aggregation response induced by 0.75 and 2 mcg of collagen was decreased in the flaxseed oil-fed group. The authors suggested that ingesting flaxseed oil may protect against cardiovascular disease through decreased platelet aggregation.4
The effect on human tumor necrosis factor alpha and interleukin 1b production of diets enriched in n-3 fatty acids from vegetable oil or fish oil
Thirty healthy male subjects were given flaxseed oil (daily average intake 13.7 g) or sunflower oil (daily average intake 1.1 g) for 4 weeks and switched to fish oil (9 g/day) for a further 4 weeks. Tumor necrosis factor alpha and interleukin 1b production were reduced in mononuclear cells by approximately 30% in the flaxseed oil/fish oil group. Further intake of fish oil inhibited cytokine production by approximately 80%. Cytokine production was inversely related to the increase of EPA, an n-3 fatty acid derived from both flaxseed oil and fish oil. This result may indicate that feeding n-3 fatty acid, from flaxseed oil or fish oil, may reduce the risk of inflammatory disorders such as rheumatoid arthritis and atherosclerosis.5
Supplementing lactating women with flaxseed oil does not increase docosahexaenoic acid in their milk
Seven lactating mothers between the ages of 28 and 39 years old were given 20 g of flaxseed oil per day (10.7 g ALA) for a period of four weeks. ALA and DPA concentrations were found to significantly increase in breast milk, plasma, and erythrocytes. EPA concentrations were found to increase significantly in breast milk and plasma. No changes in DHA concentrations were detected. Flaxseed oil supplementation, while significantly increasing ALA, DPA, and EPA concentrations in breast milk, is not a way to increase DHA concentrations in breast milk.6
Supplementation with flaxseed alters estrogen metabolism in postmenopausal women to a greater extent than does supplementation with an equal amount of soy
Forty-six postmenopausal women were randomly assigned to receive either 25 grams ground flaxseed, 25 grams soy flour, or a placebo daily for 16 weeks to evaluate the effects of these supplements on estrogen metabolism. Flaxseed supplementation, but not soy flour or placebo, increased urinary excretion of 2-hydroxyestrone, a primary metabolite of estrogen. Excretion of 16 alpha-hydroxyestrone, another major metabolite of estrogen was not changed in any group. The ratio of 2-hydroxyestrone to 16 alpha-hydroxyestrone was positively correlated to the levels of urinary lignan. The authors cautiously suggest that ground flaxseed may have beneficial effects on estrogen metabolism for postmenopausal women.7
Dietary flaxseed alters tumor biological markers in postmenopausal breast cancer
Thirty-two postmenopausal women with diagnosed breast cancer participated in a study of the effects of dietary flaxseed on breast cancer. Subjects received either 25 grams/day of flaxseed (19 subjects) or a placebo (13 subjects) from the date of diagnosis to the date the tumor was surgically removed, approximately 35 days. Consumption of flaxseed increased tumor cell death (apoptosis) and decreased biomarkers of tumor cell growth. These results suggest that flaxseed may help reduce tumor growth in women with breast cancer.8
The dietary supplement information contained on this site has been compiled from published sources thought to be reliable, but it cannot be guaranteed. Efforts have been made to assure this information is accurate and current. However, some of this information may be purported or outdated due to ongoing research or discoveries. The authors, editors and publishers cannot accept responsibility for errors or omissions or for any consequences from applications of the information in this site and make no warranty, expressed or implied, with respect to the contents herein.
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