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Flaxseed and Flaxseed oil

 

Natural Standard Monograph, Copyright © 2014 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified health care professional before making decisions about therapies and/or health conditions.

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

 

Uses based on scientific evidence 

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 professional.

Grade* 

Constipation 

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 

Attention-deficit hyperactivity disorder (ADHD) 

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 

Bipolar disorder 

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 

Breast cancer 

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 

Breast pain 

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 

Clogged arteries 

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 

Diabetes 

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

C 

Dry eye syndrome 

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 

Enlarged prostate 

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 

Heart disease 

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 

High blood pressure 

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 

High cholesterol 

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 

HIV/AIDS (weight gain) 

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 

Irritable bowel 

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 

Lupus nephritis 

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 

Menopausal symptoms 

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 

Metabolic syndrome 

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 

Obesity 

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 

Pneumonia (community acquired) 

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 

Polycystic ovarian syndrome (hormonal disorder)  

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 

Premature infants 

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 

Pressure ulcers 

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

C 

Prostate cancer 

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 

Skin conditions (sensitivity) 

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 

Antioxidant 

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 

Exercise performance enhancement 

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 

Osteoporosis 

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 against this use (it may not work);
F: Strong scientific evidence against this use (it likely does not work).

For full grading rationale, click here.

Uses based on tradition or theory 

The below uses are based on tradition or scientific theories. 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 health care professional

Acne, acute respiratory distress syndrome (ARDS), allergic reactions, bladder inflammation, blood thinner, boils, bronchial irritation, burns (poultice), catarrh (inflammation of mucous membranes), colon cancer, common cold / upper respiratory tract infection, cough suppressant, diabetic nephropathy (kidney disease), diarrhea, diverticulitis (growths in colon), dysentery (severe diarrhea), enteritis (small intestine inflammation), expectorant, gastritis (stomach inflammation), gonorrhea, headache, infections, inflammation, inflammatory bowel disease (ulcerative colitis), kidney disorders, laxative-induced colon damage, liver protection, malaria, menstrual luteal phase disorders, multiple sclerosis, ovarian disorders, psoriasis (skin disorder), rheumatoid arthritis, skin cancer, skin infections, skin inflammation, sore throat, stomach pain, stomach upset, stroke, urinary tract infection, vaginitis (vaginal inflammation), vision improvement.


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 professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.

Allergies

  • Avoid with known allergy or sensitivity to flaxseed, flaxseed oil, its parts, or any other members of the Linaceae plant family.
  • Allergic reactions to flaxseed and flaxseed powder have been reported. Itchy palms, hives, itchy eyes and weeping, nausea, and vomiting after consuming flaxseed oil was reported in one case. In another case, a man experienced 5-6 episodes of intestinal and stomach pain, vomiting, diarrhea, hives, shortness of breath, watery discharge, sneezing, stuffy nose, itching, and generally felt unwell after eating bread containing flaxseed.
  • Anaphylaxis (severe allergic reaction) has also been reported.

Side Effects and Warnings

  • Both flaxseed and flaxseed oil are likely safe when taken by mouth in suggested doses for under four months by healthy people. A part of flaxseed, alpha-linolenic acid (ALA), has been well tolerated for up to five years as part of the Mediterranean diet. Flaxseed should be ingested with adequate fluid intake (1:10 seed: liquid is suggested). Application to the skin of the seed form or poultice is generally well tolerated.
  • Flaxseed or flaxseed oil is possibly safe when used for more than four months. Flaxseed or flaxseed oil is possibly safe when used in pregnant or lactating women in amounts normally consumed in food or under guidance of a practitioner.
  • Flaxseed may lower blood sugar levels. Caution is advised in people with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
  • Flaxseed may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
  • Flaxseed may cause low blood pressure. Caution is advised in people taking drugs or herbs and supplements that lower blood pressure.
  • Use cautiously in people with prostate cancer, high triglycerides, or hypothyroidism (underactive thyroid).
  • Use cautiously in women with hormone-sensitive conditions or women taking estrogens. Use cautiously pregnant or lactating women. Use cautiously in people taking laxatives, furosemide, or ketoprofen.
  • Avoid in people with known allergy or sensitivity to flaxseed, flaxseed oil, its constituents, or any other members of the Linaceae plant family.
  • Avoid in people with acute or chronic diarrhea, diverticulitis (colon disorder), or inflammatory bowel disease. Avoid use in open wounds or scraped surfaces. Avoid flaxseed (not flaxseed oil) in people with narrowing of the esophagus/stomach/intestines or bowel obstruction.
  • Intestinal obstruction may occur when large amounts of flaxseed are ingested, or when taken without enough water or liquid (1:10 seed: liquid is suggested). Immature flaxseed seedpods may be poisonous and should not be consumed.
  • Flax may also cause abdominal pain and bloating, altered estrogen activity, bowel obstruction, cell damage, change in bowel habits, decreased absorption of drugs, vitamins or minerals, diarrhea, eye itching and weeping, gas, headache, higher or lower cholesterol, hives, increase in total red blood cell count, increased bleeding time, increased blood cyanide levels, increased prostate cancer risk, indigestion, itching, loose stools, malaise (feeling unwell), mania or hypomania, nausea, paralysis, prolonged luteal phase, rapid breathing, seizures, shortness of breath, sneezing, unstable gait, vomiting, watery discharge, weakness, weight gain or loss.

Pregnancy and Breastfeeding

  • Human evidence of medicinal use of flaxseed or flaxseed oil during pregnancy and lactation is limited.
  • A study reported that flaxseed oil supplementation led to a significant increase in ALA, eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA) in the breast milk. Fatty acid levels in breast milk returned to baseline one week after discontinuing supplementation.
  • In a survey, flax was reported to be one of the most frequently used herbal products by the pregnant women surveyed.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. 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 professional before starting a new therapy.

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.

Interactions with Herbs and Dietary Supplements

  • 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 herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
  • Flaxseed may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
  • 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 herbs or supplements that lower blood pressure.
  • Flaxseed may also interact with anti-inflammatories, antioxidants, cholesterol lowering herbs and supplements, herbs and supplements for cancer or obesity, herbs and supplements that increase urination, laxatives, phytoestrogens, psyllium, soy, or vitamin E.

Authors

Selected References

Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

  1. Cockerell, K. M., Watkins, A. S., Reeves, L. B., Goddard, L., and Lomer, M. C. Effects of linseeds on the symptoms of irritable bowel syndrome: a pilot randomised controlled trial. J Hum Nutr Diet. 2012;25(5):435-443.
  2. Colli, M. C., Bracht, A., Soares, A. A., de Oliveira, A. L., Boer, C. G., de Souza, C. G., and Peralta, R. M. Evaluation of the efficacy of flaxseed meal and flaxseed extract in reducing menopausal symptoms. J Med Food 2012;15(9):840-845.
  3. Dewell, A., Marvasti, F. F., Harris, W. S., Tsao, P., and Gardner, C. D. Low- and high-dose plant and marine (n-3) fatty acids do not affect plasma inflammatory markers in adults with metabolic syndrome. J Nutr 2011;141(12):2166-2171.
  4. Diesel, H. J. and Ercole, P. M. Soothability and growth in preterm infants. J Holist.Nurs. 2012;30(1):38-47.
  5. Geleijnse, J. M., Giltay, E. J., and Kromhout, D. Effects of n-3 fatty acids on cognitive decline: a randomized, double-blind, placebo-controlled trial in stable myocardial infarction patients. Alzheimers.Dement. 2012;8(4):278-287.
  6. Gillingham, L. G., Robinson, K. S., and Jones, P. J. Effect of high-oleic canola and flaxseed oils on energy expenditure and body composition in hypercholesterolemic subjects. Metabolism 2012;61(11):1598-1605.
  7. Haug, A., Nyquist, N. F., Mosti, T. J., Andersen, M., and Hostmark, A. T. Increased EPA levels in serum phospholipids of humans after four weeks daily ingestion of one portion chicken fed linseed and rapeseed oil. Lipids Health Dis 2012;11:104.
  8. Ibrugger, S., Kristensen, M., Mikkelsen, M. S., and Astrup, A. Flaxseed dietary fiber supplements for suppression of appetite and food intake. Appetite 2012;58(2):490-495.
  9. Intorre, F., Foddai, M. S., Azzini, E., Martin, B., Montel, M. C., Catasta, G., Toti, E., Finotti, E., Palomba, L., Venneria, E., Raguzzini, A., Fumagalli, A., Testa, M. F., Rossi, L., and Maiani, G. Differential effect of cheese fatty acid composition on blood lipid profile and redox status in normolipidemic volunteers: a pilot study. Int J Food Sci Nutr 2011;62(6):660-669.
  10. Mani, U. V., Mani, I., Biswas, M., and Kumar, S. N. An open-label study on the effect of flax seed powder (Linum usitatissimum) supplementation in the management of diabetes mellitus. J Diet.Suppl 2011;8(3):257-265.
  11. Pruthi, S., Qin, R., Terstreip, S. A., Liu, H., Loprinzi, C. L., Shah, T. R., Tucker, K. F., Dakhil, S. R., Bury, M. J., Carolla, R. L., Steen, P. D., Vuky, J., and Barton, D. L. A phase III, randomized, placebo-controlled, double-blind trial of flaxseed for the treatment of hot flashes: North Central Cancer Treatment Group N08C7. Menopause. 2012;19(1):48-53.
  12. Rhee, Y. and Brunt, A. Flaxseed supplementation improved insulin resistance in obese glucose intolerant people: a randomized crossover design. Nutr J 2011;10:44.
  13. Sarris, J., Mischoulon, D., and Schweitzer, I. Omega-3 for bipolar disorder: meta-analyses of use in mania and bipolar depression. J Clin Psychiatry 2012;73(1):81-86.
  14. Skorkowska-Telichowska, K., Kulma, A., Zuk, M., Czuj, T., and Szopa, J. The effects of newly developed linen dressings on decubitus ulcers. J Palliat.Med 2012;15(2):146-148.
  15. Sydenham, E., Dangour, A. D., and Lim, W. S. Omega 3 fatty acid for the prevention of cognitive decline and dementia. Cochrane Database Syst.Rev 2012;6:CD005379.
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