Flaxseed and flaxseed oil (Linum usitatissimum)
Original Article: http://www.mayoclinic.com/health/flaxseed/NS_patient-flaxseed
Flaxseed and its derivative flaxseed oil (or linseed oil) are rich sources of the essential fatty acid alpha-linolenic acid (ALA), which is a biologic precursor to omega-3 fatty acids such as eicosapentaenoic acid. Although omega-3 fatty acids have been associated with improved cardiovascular outcomes, evidence from human trials is mixed regarding the efficacy of flaxseed products for coronary artery disease or hyperlipidemia (high lipid levels).
The lignans of flaxseed (not flaxseed oil) possess in vitro antioxidant and estrogen-like properties, prompting theories about their efficacy for the treatment of breast cancer. However, there is not sufficient human evidence to make a strong conclusion. As a source of fiber, flaxseed (not flaxseed oil) taken by mouth possesses laxative properties. In large doses, or when taken with inadequate water, flaxseed may cause bowel obstruction. The effects of flaxseed on blood glucose levels are not clear, although hyperglycemic (increased blood sugar) effects have been reported with omega-3 fatty acids in general.
Flaxseed oil contains only the ALA component of flaxseed and not the fiber or lignan components. Therefore, flaxseed oil may share the purported lipid-lowering properties of flaxseed but not its proposed laxative or anticancer abilities.
Alashi, alpha-linolenic acid, Barlean's Flax Oil, Barlean's Vita-Flax, brazen, common flax, DHA, docosahexaenoic acid, eicosapentaenoic acid, EPA, Flachssamen (German), flax, gamma-linolenic acid, graine de lin (French), hu-ma-esze (Chinese), keten (Turkish), Leinsamen (German), Linaceae (family), 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).
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.
ConstipationIt has been suggested that flaxseed (not flaxseed oil) produces laxative effects. However, further evidence is needed to establish efficacy and dosing. Notably, in large doses, or when taken with inadequate water, flaxseed may precipitate bowel obstruction.
AtherosclerosisIt has been suggested that flaxseed and its lignans may exert a beneficial effect on atherosclerotic plaque formation or cardiovascular outcomes, based on their purported antioxidant and lipid-lowering properties. Despite this evidence, it remains unclear if flaxseed supplementation improves human cardiovascular endpoints, and dosing regimens are lacking.
Attention-deficit hyperactivity disorder (ADHD)Preliminary evidence supports the idea that deficiencies or imbalances in certain highly unsaturated fatty acids may contribute to attention-deficit hyperactivity disorder (ADHD). According to one trial, alpha-linolenic acid (ALA)-rich nutritional supplementation in the form of flax oil may improve symptoms of ADHD. More research is needed to confirm these results.
Benign prostatic hypertrophy (BPH)Limited research suggests that flaxseed lignan extract may alleviate lower urinary tract symptoms (LUTS) in patients with benign prostatic hyperplasia (BPH). Additional well-designed trials are needed before a conclusion can be drawn.
Breast cancerIt has been proposed that the lignan components of flaxseed may offer protection against hormone-sensitive cancers. Although organic flaxseed oil is used by many women to prevent breast cancer, and some herbal textbooks also support this claim, there is a lack of available research for or against the use of flaxseed oil, or organic flaxseed oil, for the prevention of cancer. Additional research is needed in this area.
Cyclic mastalgiaIt has been hypothesized that the hormonal effects of flaxseed may improve the symptoms of cyclic mastalgia, a condition characterized by breast pain and tenderness in women. Preliminary evidence suggests that flaxseed may reduce these symptoms. However, further research is warranted before a conclusion can be drawn.
HIV/AIDS (weight gain)Limited research suggests that ingestion of flax-derived alpha-linolenic acid (ALA), in combination with arginine and yeast RNA, was associated with weight gain in HIV patients. Further research is warranted before a conclusion may be drawn.
Hyperglycemia/diabetesPreliminary studies have reported mixed effects of oral flaxseed on serum glucose levels. Flaxseed cannot be suggested as a treatment for hyperglycemia (high blood sugar) or diabetes at this time. Further research is required before conclusions may be drawn.
HyperlipidemiaFlaxseed and flaxseed oil have been reported to possess lipid-lowering properties. Preliminary studies have examined the effects of flaxseed products on lipids, with mixed results. Additional research is needed at this time.
Hypertension (high blood pressure)Preliminary research suggests that two weeks of flaxseed supplementation may lower blood pressure. However, at this time there are insufficient data to recommend for or against this use of flaxseed.
Keratoconjunctivitis sicca (dry eye syndrome)Based on popular use, manufacturer studies, and case reports, flaxseed oil has been proposed as a possible treatment for 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.
Lupus nephritisLimited research suggests possible improvements in glomerular filtration rate (GFR) and serum creatinine levels in patients treated daily with flaxseed. Further research is warranted before a conclusion may be drawn.
Menopausal symptomsPreliminary research has examined the effects of flaxseed on menopausal symptoms, such as decreases in bone mineral density and cholesterol levels in menopausal women. Additional research is necessary before a clear conclusion may be drawn, and this remains an area of controversy.
ObesityThere is limited research on the effects of flaxseed flour in obese patients. Limited early research has not shown evidence of benefit for weight loss or the reduction of the body mass index of obese patients. However, there may be a role for flax in treating inflammation associated with obesity. Additional research is needed in this area.
PregnancyIt has been proposed that alpha-linolenic acid (ALA), provided as flax oil capsules, may delay the timing of spontaneous delivery, but evidence supporting this use is lacking.
Prostate cancerRecent research suggests that flax may be useful in the treatment of prostate cancer. Additional high-quality human research is needed in this area.
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)
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 healthcare provider.
Abdominal pain, acne, acute respiratory distress syndrome (ARDS), allergic reactions (delayed hypersensitivity reactions), anticoagulant (blood thinner), antioxidant, antiplatelet agent, bipolar disorder, bladder inflammation, boils, bowel irritation, bronchial irritation, burns (poultice), catarrh (inflammation of mucous membranes), colon cancer, cough suppressant, cystitis, depression, diabetic nephropathy, diarrhea, diverticulitis, dry skin, dysentery (severe diarrhea), eczema (skin rashes), enteritis (intestinal inflammation), expectorant, eye cleansing (debris in the eye), gastritis (stomach inflammation), glomerulonephritis (a type of kidney inflammation), gonorrhea, headache, infections, inflammation, interstitial nephritis (a type of kidney inflammation), irritable bowel syndrome, laxative-induced colon damage, liver protection, malaria, melanoma, menstrual luteal phase disorders, multiple sclerosis, ovarian disorders, pharyngitis, pimples, psoriasis, rheumatoid arthritis, skin infections, skin inflammation, skin irritation (emollient), sore throat, stomach pain, stomach upset, stroke, systemic lupus erythematosus (an autoimmune disorder), ulcerative colitis, upper respiratory tract infection, urinary tract infection, vaginitis (vaginal inflammation), vision improvement.
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
Adults (18 years and older)
Flaxseed oil is most often taken by mouth in a liquid form, which contains approximately seven grams of alpha-linolenic acid (ALA) and approximately 130 calories per 15-milliliter tablespoon.
Flaxseed oil capsules (one or two grams) have been taken by mouth daily for 180 days.
Flaxseed flour (30-100 grams) may be mixed with water to form a moist compress and applied to the skin three times daily.
A single whole flaxseed has been placed under the eyelid to allow a foreign body or mucus to adhere to it, thereby facilitating removal from the eye. This process may be unsafe, and it is suggested that a healthcare professional be consulted for removal of foreign bodies from the eye.
For benign prostatic hypertrophy (BPH), 300 and 600 milligrams of a flaxseed lignan extract have been taken by mouth daily for four months.
For breast cancer, 5-25 grams daily has been taken by mouth for up to four months.
For cyclic mastalgia, flax muffins or baked products, with flax contents of 25-50 grams, are commonly taken by mouth in clinical trials for up to six months.
For diabetes, flax muffins or baked products, with flax contents of 25-50 grams, are commonly taken by mouth in clinical trials for up to six months.
For gastritis or enteritis, one tablespoon of whole or bruised flaxseed mixed with 150 milliliters of liquid has been taken by mouth 2-3 times daily.
For hyperlipidemia, flax muffins or baked products, with flax contents of 25-50 grams, are commonly taken by mouth in clinical trials for up to six months.
As a laxative, 2-3 tablespoons of bulk flaxseed mixed in 10 times the amount of water have been taken by mouth; 45 grams daily has also been used.
For menopausal symptoms, 5-25 grams has been taken by mouth daily for up to four months; 40 grams of flaxseed has also been taken by mouth daily.
For lupus nephritis, 30 grams of flaxseed has been taken by mouth daily.
For obesity, 30 grams of flaxseed flour has been taken by mouth daily for two weeks.
Children (under 18 years old)
For attention-deficit hyperactivity disorder (ADHD), flax oil (200 milligrams of ALA content), along with 25 milligrams of vitamin C, has been taken by mouth twice daily for three months.
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.
Avoid with a known allergy or hypersensitivity to flaxseed ( Linum usitatissimum ), flaxseed oil, its constituents, or any other members of the Linaceae plant family. Hypersensitivity reactions to flaxseed following occupational exposure have been reported. Diarrhea; intestinal and abdominal pain; itching, including itchy palms and soles and itchy, weeping eyes; hives; malaise; nasal obstruction; nausea; shortness of breath; sneezing; vomiting; and watery discharge have been reported.
Side Effects and Warnings
Flaxseed may cause gastrointestinal symptoms, headache, "heart problems," hives, increased red blood cell counts, increased risk of prostate cancer, intestinal obstruction, mania or hypomania (in bipolar patients), prolonged luteal phases, rapid breathing, respiratory disease (in flax farmers), vomiting, and weight gain or weight loss. An overdose of flaxseed or flaxseed oil may result in weakness, unstable gait, paralysis, or seizures.
Raw flaxseed or flaxseed plant may increase blood levels of cyanide, a toxic chemical.
Flaxseed may cause low blood pressure. Caution is advised in patients with blood pressure disorders and those taking drugs, herbs, or supplements that affect blood pressure.
Based on the available evidence, flaxseed, which contains alpha-linolenic acid (ALA), should be avoided in patients with prostate cancer or those at risk for prostate cancer.
Use flaxseed and flaxseed oil cautiously in patients with elevated triglycerides, as these agents may raise or lower triglyceride levels.
Flaxseed may increase the risk of bleeding and bleeding time. Caution is advised in patients with bleeding disorders or those taking drugs, herbs, or supplements that may increase the risk of bleeding. Dosing adjustments may be necessary.
Flaxseed may lower blood sugar levels. Caution is advised in patients with diabetes or low blood sugar, 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. Medication adjustments may be necessary.
Use cautiously in patients using laxatives, as flaxseed, particularly at higher doses (more than 30 grams daily), caused loose stools; theoretically, concurrent use may increase the risk of diarrhea.
Use cautiously in patients using furosemide or ketoprofen, as flaxseed decreased the absorption of these drugs.
Because flaxseed contains estrogen-like chemicals, the effects of other agents believed to have estrogen-like properties may be altered.
Use flaxseed (not flaxseed oil) cautiously in women with hormone-sensitive conditions, due to its possible estrogenic properties.
Avoid consumption of immature flaxseed seedpods, as they may be poisonous.
Avoid topical flaxseed on open wounds or abraded surfaces.
Avoid flaxseed (not flaxseed oil) in patients with esophageal stricture, ileus, gastrointestinal stricture, or bowel obstruction. Ingestion of flaxseed without adequate fluids may precipitate bowel obstruction.
Avoid in patients with acute or chronic diarrhea, irritable bowel disease, diverticulitis (small, bulging sacs or pouches of the inner lining of the intestine that become inflamed or infected), or inflammatory bowel disease, due to the potential laxative effect of flaxseed.
Some natural medicine textbooks advise caution in patients with hypothyroidism, although scant clinical data exist in this area.
Avoid in pregnant or breastfeeding women, due to a lack of available scientific evidence and safety information.
Avoid with a known allergy or hypersensitivity to flaxseed ( Linum usitatissimum ), flaxseed oil, their constituents, or any other members of the Linaceae plant family. Hypersensitivity reactions to flaxseed following occupational exposure have been reported. Diarrhea; intense general malaise; intestinal and abdominal pain; itching, including itchy palms and soles and itchy, weeping eyes; hives; nasal obstruction; nausea; shortness of breath; sneezing; vomiting; and watery discharge have been reported.
Pregnancy and Breastfeeding
Avoid in pregnant or breastfeeding women, due to a lack of available scientific evidence and safety information.
This patient information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
- Barcelo-Coblijn G, Murphy EJ, Othman R, et al. Flaxseed oil and fish-oil capsule consumption alters human red blood cell n-3 fatty acid composition: a multiple-dosing trial comparing 2 sources of n-3 fatty acid. Am J Clin Nutr 2008;88(3):801-809.
- Barre DE, Mizier-Barre KA, Griscti O, et al. High dose flaxseed oil supplementation may affect fasting blood serum glucose management in human type 2 diabetics. J Oleo Sci 2008;57(5):269-273.
- Basch E, Bent S, Collins J, et al. Flax and flaxseed oil ( Linum usitatissimum ): a review by the Natural Standard Research Collaboration. J Soc Integr Oncol 2007;5(3):92-105.
- Bloedon LT, Balikai S, Chittams J, et al. Flaxseed and cardiovascular risk factors: results from a double blind, randomized, controlled clinical trial. J Am Coll Nutr 2008;27(1):65-74.
- Dodin S, Lemay A, Jacques H, et al. The effects of flaxseed dietary supplement on lipid profile, bone mineral density, and symptoms in menopausal women: a randomized, double-blind, wheat germ placebo-controlled clinical trial. J Clin Endocrinol Metab 2005;90(3):1390-1397.
- Harper CR, Edwards MJ, DeFilippis AP, et al. Flaxseed oil increases the plasma concentrations of cardioprotective (n-3) fatty acids in humans. J Nutr 2006;136(1):83-87.
- Jenkins DJ, Kendall CW, Vidgen E, et al. Health aspects of partially defatted flaxseed, including effects on serum lipids, oxidative measures, and ex vivo androgen and progestin activity: a controlled crossover trial. Am J Clin Nutr 1999;69(3):395-402.
- Kaul N, Kreml R, Austria JA, et al. A comparison of fish oil, flaxseed oil and hempseed oil supplementation on selected parameters of cardiovascular health in healthy volunteers. J Am Coll Nutr 2008;27(1):51-58.
- Knudsen VK, Hansen HS, Osterdal ML, et al. Fish oil in various doses or flax oil in pregnancy and timing of spontaneous delivery: a randomised controlled trial. BJOG 2006;113(5):536-543.
- Legrand P, Schmitt B, Mourot J, et al. The consumption of food products from linseed-fed animals maintains erythrocyte omega-3 fatty acids in obese humans. Lipids 2010;45(1):11-9.
- Lewis JE, Nickell LA, Thompson LU, et al. A randomized controlled trial of the effect of dietary soy and flaxseed muffins on quality of life and hot flashes during menopause. Menopause 2006;13(4):631-642.
- Makrides M, Neumann MA, Jeffrey B, et al. A randomized trial of different ratios of linoleic to alpha-linolenic acid in the diet of term infants: effects on visual function and growth. Am J Clin Nutr 2000;71(1):120-129.
- Nordstrom DC, Honkanen VE, Nasu Y, et al. Alpha-linolenic acid in the treatment of rheumatoid arthritis. A double- blind, placebo-controlled and randomized study: flaxseed vs. safflower seed. Rheumatol Int 1995;14(6):231-234.
- Stoll AL, Severus WE, Freeman MP, et al. Omega 3 fatty acids in bipolar disorder: a preliminary double-blind, placebo-controlled trial. Arch Gen Psychiatry 1999;56(5):407-412.
- Stuglin C, Prasad K. Effect of flaxseed consumption on blood pressure, serum lipids, hemopoietic system and liver and kidney enzymes in healthy humans. J Cardiovasc Pharmacol Ther 2005;10(1):23-27.