Flaxseed and flaxseed oil

Related Terms

Alashi, alpha-linolenic acid, Barlean's Flax Oil, Barlean's Vita-Flax, brazen, common flax, DHA, docosahexaenoic acid, docosapentaenoic acid, DPA, eicosapentaenoic acid, EPA, Flachssamen (German), flax, gamma-linolenic acid, graine de lin (French), hu-ma-esze (Chinese), keten (Turkish), Leinsamen (German), Linaceae, linen flax, Lini semen, lino (Spanish, Italian), lino usuale (Italian), linseed, linseed oil, lint bells, linum, Linum catharticum, Linum humile seeds, omega-3 fatty acid, phytoestrogen, prebiotic bread, sufulsi, tesi-mosina, Type I Flaxseed/Flaxseed (51-55% alpha-linolenic acid), Type II Flaxseed/CDC-flaxseed (2-3% alpha-linolenic acid), Winterlien (German).

Background

Flaxseed and flaxseed oil (or linseed oil) are rich sources of the essential fatty acid alpha-linolenic acid (ALA). In the body, some ALA is converted to omega-3 fatty acids.
Lignans are a type of plant hormone similar to estrogen. The lignan components of flaxseed (not flaxseed oil) may possess antioxidant properties and alter estrogen activity.
As a source of fiber, flaxseed (not flaxseed oil) has laxative properties. In large doses, or when taken without enough water, flaxseed may cause bowel obstruction. The effects of flaxseed on blood sugar levels are unclear.
Flaxseed oil contains only the ALA component of flaxseed and not the fiber or lignan components. Therefore, flaxseed oil may share the potential cholesterol-lowering properties of flaxseed, but not the proposed laxative or anticancer abilities.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *


Good evidence suggests that flaxseed (not flaxseed oil) produces laxative effects. Loose stools have been seen in people taking flaxseed. Further research is needed to establish efficacy and dosing. Flaxseed in large doses, or when taken without enough water, may cause bowel obstruction.

 B


Good evidence suggests that flaxseed (not flaxseed oil) produces laxative effects. Loose stools have been seen in people taking flaxseed. Further research is needed to establish efficacy and dosing. Flaxseed in large doses, or when taken without enough water, may cause bowel obstruction.

 B


Early evidence suggests that low levels or imbalances in certain highly unsaturated fatty acids may contribute ADHD. ALA-rich nutritional supplementation in the form of flax oil may improve symptoms of ADHD. More research is needed to confirm these results.

 C


Early evidence suggests that low levels or imbalances in certain highly unsaturated fatty acids may contribute ADHD. ALA-rich nutritional supplementation in the form of flax oil may improve symptoms of ADHD. More research is needed to confirm these results.

 C


The effect of flaxseed oil in children with bipolar disorder has been examined. However, a significant effect was not reported. Further research is needed.

 C


The effect of flaxseed oil in children with bipolar disorder has been examined. However, a significant effect was not reported. Further research is needed.

 C


It has been proposed that the lignan components of flaxseed may protect against hormone-sensitive cancers. Early evidence suggests that flaxseed supplementation may benefit the prevention or treatment of breast cancer. Additional research is needed in this area.

 C


It has been proposed that the lignan components of flaxseed may protect against hormone-sensitive cancers. Early evidence suggests that flaxseed supplementation may benefit the prevention or treatment of breast cancer. Additional research is needed in this area.

 C


Flaxseed (not flaxseed oil) contains lignans that may alter estrogen activity. The hormonal effects of flaxseed may improve symptoms of breast pain. However, further research is needed before a conclusion may be drawn.

 C


Flaxseed (not flaxseed oil) contains lignans that may alter estrogen activity. The hormonal effects of flaxseed may improve symptoms of breast pain. However, further research is needed before a conclusion may be drawn.

 C


Flaxseed may improve clogged arteries or cardiovascular outcomes, based on antioxidant and lipid-lowering properties. n-3 polyunsaturated fatty acids and ALA may benefit individuals with heart disease. Diets rich in ALA, such as the Mediterranean diet, have improved outcomes in people with a previous heart attack. Additional research is needed in this area.

 C


Flaxseed may improve clogged arteries or cardiovascular outcomes, based on antioxidant and lipid-lowering properties. n-3 polyunsaturated fatty acids and ALA may benefit individuals with heart disease. Diets rich in ALA, such as the Mediterranean diet, have improved outcomes in people with a previous heart attack. Additional research is needed in this area.

 C


Flax has been studied for its effects on blood sugar, but reports are inconclusive. Further research is needed in this area.

 C


Flax has been studied for its effects on blood sugar, but reports are inconclusive. Further research is needed in this area.

 C


Limited research suggests that flaxseed oil capsules daily may be useful in the treatment of dry eye syndrome. Additional research is needed in this area.

 C


Limited research suggests that flaxseed oil capsules daily may be useful in the treatment of dry eye syndrome. Additional research is needed in this area.

 C


A flaxseed lignan extract has been reported to improve urinary tract symptoms in people with benign prostatic hyperplasia (enlarged prostate). Additional well-designed trials are needed before a conclusion may be drawn.

 C


A flaxseed lignan extract has been reported to improve urinary tract symptoms in people with benign prostatic hyperplasia (enlarged prostate). Additional well-designed trials are needed before a conclusion may be drawn.

 C


Flaxseed may improve clogged arteries or cardiovascular outcomes, based on antioxidant and lipid-lowering properties. In humans, increased consumption of ALA may protect against stroke. However, evidence is mixed. Additional research is needed in this area.

C


Flaxseed may improve clogged arteries or cardiovascular outcomes, based on antioxidant and lipid-lowering properties. In humans, increased consumption of ALA may protect against stroke. However, evidence is mixed. Additional research is needed in this area.

C


Early evidence suggests that higher levels of ALA in fat tissues may be associated with lower blood pressure. Flaxseed-supplemented diets have lowered blood pressure in human studies. However, future research is needed in this area.

 C


Early evidence suggests that higher levels of ALA in fat tissues may be associated with lower blood pressure. Flaxseed-supplemented diets have lowered blood pressure in human studies. However, future research is needed in this area.

 C


Flaxseed and flaxseed oil have been reported to have lipid-lowering properties. Multiple human studies on flax had mixed results on cholesterol. Additional research is needed in this area.

 C


Flaxseed and flaxseed oil have been reported to have lipid-lowering properties. Multiple human studies on flax had mixed results on cholesterol. Additional research is needed in this area.

 C


Limited research suggests that ALA (derived from flax) with arginine and yeast RNA aided weight gain in people with HIV. Further research is needed before a conclusion may be drawn.

 C


Limited research suggests that ALA (derived from flax) with arginine and yeast RNA aided weight gain in people with HIV. Further research is needed before a conclusion may be drawn.

 C


It has been suggested that flaxseed (not flaxseed oil) produces laxative effects. Loose stools have been observed in people taking flaxseed. Further research is needed to establish efficacy and dosing. In large doses, or when taken without enough water, flaxseed may cause bowel obstruction.

 C


It has been suggested that flaxseed (not flaxseed oil) produces laxative effects. Loose stools have been observed in people taking flaxseed. Further research is needed to establish efficacy and dosing. In large doses, or when taken without enough water, flaxseed may cause bowel obstruction.

 C


Limited research suggests flaxseed may improve kidney function in people with lupus nephritis (inflamed kidney). Further research is needed before a conclusion may be drawn.

 C


Limited research suggests flaxseed may improve kidney function in people with lupus nephritis (inflamed kidney). Further research is needed before a conclusion may be drawn.

 C


Early research suggests that flaxseed may improve menopausal symptoms, such as bone mineral density and cholesterol. However, the effects of flaxseed on menopausal symptoms are mixed. Additional research is needed.

 C


Early research suggests that flaxseed may improve menopausal symptoms, such as bone mineral density and cholesterol. However, the effects of flaxseed on menopausal symptoms are mixed. Additional research is needed.

 C


Flaxseed has been studied for disorders of metabolic syndrome (high blood pressure, cholesterol, and diabetes) with mixed results. Trials on people with metabolic syndrome are also inconclusive. Further research is needed.

 C


Flaxseed has been studied for disorders of metabolic syndrome (high blood pressure, cholesterol, and diabetes) with mixed results. Trials on people with metabolic syndrome are also inconclusive. Further research is needed.

 C


Limited research exists on the effects of flaxseed in obese patients. Early research has lacked evidence of benefit in weight loss. Flaxseed has caused a reduction in hunger and an increase in fullness. Further research is needed.

 C


Limited research exists on the effects of flaxseed in obese patients. Early research has lacked evidence of benefit in weight loss. Flaxseed has caused a reduction in hunger and an increase in fullness. Further research is needed.

 C


Limited data exists on flaxseed use for community-acquired pneumonia. Seeds from the plant have historically been used for upper respiratory infections. Further well-controlled trials are needed to confirm this conclusion.

 C


Limited data exists on flaxseed use for community-acquired pneumonia. Seeds from the plant have historically been used for upper respiratory infections. Further well-controlled trials are needed to confirm this conclusion.

 C


Flaxseed has been studied for several aspects of polycystic ovarian syndrome, including insulin resistance, obesity, and hormone changes, with mixed results. Further research is needed in this area.

 C


Flaxseed has been studied for several aspects of polycystic ovarian syndrome, including insulin resistance, obesity, and hormone changes, with mixed results. Further research is needed in this area.

 C


It has been proposed that ALA may delay the timing of spontaneous delivery, but the available evidence lacks support for this use. The use of a flaxseed pillow in premature infants has also been studied.

 C


It has been proposed that ALA may delay the timing of spontaneous delivery, but the available evidence lacks support for this use. The use of a flaxseed pillow in premature infants has also been studied.

 C


Flaxseed dressings on pressure ulcers have been studied. Future well-controlled trials are needed in this area.

 C


Flaxseed dressings on pressure ulcers have been studied. Future well-controlled trials are needed in this area.

 C


There are conflicting reports on ALA and prostate cancer. Several studies suggest benefit while other studies have associated ALA with an increased risk of prostate cancer. Additional high quality studies are needed.

 C


There are conflicting reports on ALA and prostate cancer. Several studies suggest benefit while other studies have associated ALA with an increased risk of prostate cancer. Additional high quality studies are needed.

 C


Seeds from the flax plant have historically been used for skin inflammation. Flaxseed oil has been applied to the skin as a salve or used for sore throat. Flaxseed oral supplementation has been studied in women with skin sensitivities. Further research is needed in this area.

 C


Seeds from the flax plant have historically been used for skin inflammation. Flaxseed oil has been applied to the skin as a salve or used for sore throat. Flaxseed oral supplementation has been studied in women with skin sensitivities. Further research is needed in this area.

 C


Flaxseed oil and its lignin have been found to possess antioxidant properties. Diets supplemented with flaxseed (not flaxseed oil) have been associated with an increase in cell damage. Additional research is needed.

 D


Flaxseed oil and its lignin have been found to possess antioxidant properties. Diets supplemented with flaxseed (not flaxseed oil) have been associated with an increase in cell damage. Additional research is needed.

 D


Limited research exists on the effects of flaxseed for improving resistance training. Taking flax oil lacked an effect on resistance training. Further research is needed.

 D


Limited research exists on the effects of flaxseed for improving resistance training. Taking flax oil lacked an effect on resistance training. Further research is needed.

 D


Phytoestrogens, like flaxseed, have been studied for their effects on the prevention and treatment of osteoporosis. Several studies have lacked a significant effect of flaxseed on osteoporosis risk or bone mineral density. Further study is needed in this area.

 D


Phytoestrogens, like flaxseed, have been studied for their effects on the prevention and treatment of osteoporosis. Several studies have lacked a significant effect of flaxseed on osteoporosis risk or bone mineral density. Further study is needed in this area.

 D
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Dosing

Adults (18 years and older)
General: Flaxseed oil is most often used in a liquid form, which contains approximately 7 grams of ALA and approximately 130 calories per 15 milliliters or 1 tablespoon. Flaxseed oil is available in a capsule form, which often contains 500 milligrams of ALA per 1,000 milligrams capsule (10 calories).
Whole or bruised (not ground) flaxseed may be mixed with water or juice and ingested. Generally, one tablespoon in this form may be mixed with 6-12 ounces of liquid and taken up to three times daily. Some studies have used up to 60-80 grams per kilogram of soluble flaxseed mucilage or fiber. These forms of flaxseed should not be confused with preparations of flaxseed oil.
In several studies, adults have consumed up to 50 grams of ground raw flaxseeds daily for periods not exceeding four weeks. Generally, the higher the dose, the greater the risk of gastrointestinal side effects. A dose of 50 grams of flaxseeds daily may correlate with 250 grams of flaxseed flour. In large doses, or when taken without enough water, flaxseed may cause bowel obstruction. At high temperatures, such as cooking, flaxseed oil and powder or flour will degrade.
For breast cancer, 10-25 grams of flaxseed or 5-25 grams of ground flaxseed has been taken by mouth daily for up to 16 weeks.
For breast pain (mastalgia), a muffin containing 25 grams of flaxseed has been taken by mouth daily for six months.
For constipation, 2-3 tablespoons of bulk seed mixed in 10 times the amount of water or 45 grams of bulk seed daily has been taken by mouth. Up to 15 grams of fiber from a flax fiber supplement has been taken by mouth for two weeks.
For diabetes, three capsules containing lignan (0.6 grams per capsule, which provided a total of 360 milligrams of isolated flaxseed lignan) have been taken by mouth daily for 12 weeks. Additionally, 40-50 grams of flaxseed, 32 grams of milled flaxseed, 13 grams of flaxseed oil, or 10 grams of flaxseed powder has been taken by mouth for up to 12 weeks.
For dry eye syndrome, 1-2 grams of flaxseed oil capsules have been taken by mouth daily for 180 days.
For enlarged prostate (benign prostatic hypertrophy), 300 and 600 milligrams of a flaxseed lignan extract containing 33% secoisolariciresinol diglucoside (SDG) have been taken by mouth for four months.
For exercise performance enhancement, 30 milliliters of flaxseed oil has been taken by mouth daily for 12 weeks.
For heart disease, 10-30 milliliters of flaxseed oil (containing 4.5 -13.5 grams of ALA) has been taken by mouth daily for 10-12 months.
For high blood pressure, 15-60 milliliters of flaxseed oil or three tablets containing 550 milligrams of flax extract have been taken by mouth daily for up to six months.
For high cholesterol, 20-50 grams of flaxseed (whole, ground, or defatted), flaxseed oil containing 1-38 grams of ALA, 5.2-16 grams or 60 milliliters of flaxseed oil, 200-600 milligrams of flaxseed lignan, 10 grams of flaxseed powder, flaxseed oil extract, and flaxseed-containing muffins, breads, and margarine have been used taken by mouth daily for 2-52 weeks.
For irritable bowel syndrome, 24 grams (two tablespoons) of whole flaxseed or ground flaxseed has been taken by mouth daily for four weeks. One tablespoon of whole or bruised seed mixed with 150 milliliters of liquid has reportedly been taken by mouth 2-3 times daily.
For lupus, 30 grams of flaxseed has been taken by mouth daily for four weeks.
For menopausal symptoms, 5-45 grams of flaxseed, ground flaxseed, or two 500 milligram capsules have been taken by mouth daily for up to 12 months.
For metabolic syndrome, 3-12 capsules of flaxseed oil (550 milligrams of ALA per capsule), 30 grams of flaxseed or 550 milligrams of flax extract have been taken by mouth daily for up to six months.
For obesity, 30 grams of flaxseed flour (5 grams of ALA and omega-3), 60 grams of flaxseed, a 300 milliliter flax drink, or seven tablets with flax fiber extract have been taken by mouth for up to 12 weeks. A diet of animal products from animals fed 5% linseed, as well as plant products consisting of 5 grams of extruded linseed flour, and bread with 4% extruded linseed flour, has been consumed daily for 90 days.
For osteoporosis, 40 grams of flaxseed or ground flaxseed, 30 milliliters flaxseed oil, or 550 milligrams of flax extract have been taken by mouth daily for up to 12 months.
For polycystic ovarian syndrome, six capsules of flaxseed oil containing 545 milligrams of ALA (Barleans Organic Oils, Ferndale, WA) have been taken by mouth daily for six weeks.
For premature infants, 2.2 grams of ALA has been taken by mouth daily as flax oil from week 17-27 of gestation until delivery.
For pressure ulcers, FlaxAid dressings were applied daily to the skin for 12 weeks.
For prostate cancer, a diet supplemented with 30 grams of flaxseed has been taken by mouth for at least 21 days before surgery.
For skin conditions (sensitivity), two capsules of flaxseed oil were taken with breakfast and two with dinner daily for 12 weeks. Additionally, four capsules of flaxseed oil (555.32 milligrams per capsule) have been taken by mouth daily for 12 weeks. Additionally, 30-100 grams of flaxseed flour may be mixed with warm or hot water to form a moist compress up to three times daily.
Flaxseeds have been used for foreign body removal in the eye by placing a single whole flaxseed under the eyelid and allowing the foreign body or mucus to adhere to it. This process may be unsafe, and it is suggested that a healthcare professional be consulted for removal of foreign bodies from the eye.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Interactions

Interactions with Drugs
General: Consumption of flaxseed (not flaxseed oil) may decrease the absorption of other drugs, vitamins, or minerals. Oral agents should be taken one hour before or two hours after flaxseed to prevent decreased absorption.
Flaxseed may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
Flaxseed may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin?) or heparin, anti-platelet drugs such as clopidogrel (Plavix?), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin?, Advil?) or naproxen (Naprosyn?, Aleve?).
Because flaxseed contains estrogen like chemicals, the effects of other agents believed to have estrogen-like properties may be altered.
Flaxseed may cause low blood pressure. Caution is advised in people taking drugs that lower blood pressure.
Flaxseed may also interact with agents for cancer or obesity; anti-inflammatories; cholesterol lowering agents; estrogens; laxatives; or loop diuretics.

Attribution

This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

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