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- Although studies report conflicting results, the omega-3 fatty acids in flaxseed and flaxseed oil may increase blood sugar, reducing the effects of diabetes treatments, including insulin and glucose-lowering medications taken by mouth.<a href="#hdng0">(More...)</a>
<a name="hdng0"></a>
Although studies report conflicting results, the omega-3 fatty acids in flaxseed and flaxseed oil may increase blood sugar, reducing the effects of diabetes treatments, including insulin and glucose-lowering medications taken by mouth. <a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> People with diabetes should use caution if taking flaxseed products by mouth, as the omega-3 fatty acids in flaxseed and flaxseed oil may increase blood sugar levels.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Flaxseed and flaxseed oil may increase the risk of bleeding, based on early studies that show decreased clotting of blood.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Theoretically, flaxseed ( not flaxseed oil) may increase the risk of cell damage from a reaction called oxidative stress. Studies report conflicting results in this area.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Flaxseed and flaxseed oil supplements do appear to be well tolerated in the available research, and there is long-standing historical use of flaxseed products without many reports of side effects.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Not enough information is available to advise use of flaxseed or flaxseed oil in children.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Flaxseed oil is available in liquid and capsule form, flaxseed powder, flour, and soluble fiber. 10 to 250 grams have been taken by mouth.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Consumption of flaxseed ( not flaxseed oil) may reduce the absorption of vitamins or supplements taken by mouth at the same time. Therefore, vitamins and supplements should be taken an hour before or two hours after a dose of flaxseed to prevent decreased absorption.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Based on one study, flaxseed or flaxseed oil taken by mouth may cause mania or hypomania in people with bipolar disorder.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Taking flaxseed ( not flaxseed oil) by mouth may reduce the absorption of other medications.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Individuals with high blood triglycerides should avoid flaxseed and flaxseed oil due to unclear effects on triglyceride levels in animal research.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Early studies in humans show that flaxseed and flaxseed oil theoretically may increase the risk of bleeding.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Flaxseed and flaxseed oil can lower cholesterol levels in animals, but studies in humans show mixed results.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> In laboratory and animal studies, flaxseed and flaxseed oil are reported to lower blood cholesterol levels.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Some studies use doses of soluble flaxseed mucilage/fiber as high as 60 to 80 grams per kilogram (1 kilogram equals 2.2 pounds) of the person's weight. These liquid forms of flaxseed should not be confused with preparations of flaxseed oil.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> The use of flaxseed or flaxseed oil during pregnancy and breastfeeding is not recommended.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Use caution when combining flaxseed ( not flaxseed oil) with supplements believed to have estrogen-like properties.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> People with known allergy to flaxseed, flaxseed oil, or any other members of the Linaceae plant family or Linum genus should avoid flaxseed products.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> People with narrowing of the esophagus or intestine, ileus, or bowel obstruction should avoid flaxseed ( not flaxseed oil).<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> In theory, the laxative effects of flaxseed ( not flaxseed oil) may cause diarrhea, increased number of bowel movements, and abdominal discomfort.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Flaxseed oil contains only the alpha-linolenic acid component of flaxseed, and not the fiber or lignan components. Therefore, flaxseed oil may share the purported lipid-lowering properties of flaxseed, but not the proposed laxative or anti-cancer abilities.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> There is not sufficient human evidence to make a recommendation. As a source of fiber mucilage, oral flaxseed (not flaxseed oil) may possess laxative properties, although only one human trial has been conducted for this indication.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> The lignan constituents of flaxseed (not flaxseed oil) possesses in vitro anti-oxidant and possible estrogen receptor agonist/antagonist properties, prompting theories of efficacy for the treatment of breast cancer.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
Flaxseed oil is used for different conditions than flaxseed, including arthritis. Both flaxseed and flaxseed oil have been used for high cholesterol levels and in an effort to prevent cancer.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Includes flowers, leaves, bark, fruit, seeds, stems, and roots. or dietary supplement A product that contains vitamins, minerals, herbs or other botanicals, amino acids, enzymes, and/or other ingredients intended to supplement the diet. The U.S. Food and Drug Administration has special labeling requirements for dietary supplements and treats them as foods, not drugs. you are using, including flaxseed or flaxseed oil. This helps to ensure safe and coordinated care.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Some studies suggest that alpha-linolenic acid (a substance found in flaxseed and flaxseed oil) may benefit people with heart disease.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Flaxseed contains lignans (phytoestrogens, or plant estrogens), while flaxseed oil preparations lack lignans.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a>
Effects of dietary fatty acids should have been most noted with diets supplemented with flaxseed or flaxseed oil and effects of phytoestrogens with flaxseed or flaxseed meal.<a href="
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=208616" TARGET="_blank"
[3]</a> Results indicate that dietary flaxseed or flaxseed oil increased the concentrations of polyunsaturated fatty acids in plasma and extraparenchymal mammary tissue.<a href="
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=208616" TARGET="_blank"
[3]</a>
Effects of diets that were supplemented with flaxseed, flaxseed oil, or flaxseed meal were evaluated and compared to effects of a control diet.<a href="
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=208616" TARGET="_blank"
[3]</a> Diets were: control without flax, CTL (n 14); 10% flaxseed supplementation, FS (n 13); 6.5% flaxseed meal supplementation, FSM (n 15); and 3.5% flaxseed oil supplementation, FSO (n 15).<a href="
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=208616" TARGET="_blank"
[3]</a>
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Section Contents:<a name="top"></a>
- Raw flaxseed or flaxseed plant may increase blood levels of cyanide, a toxic chemical (this effect has not been reported when flaxseed supplements are taken at recommended doses).<a href="#hdng1">(More...)</a>
- NCCAM is funding studies on flaxseed.<a href="#hdng2">(More...)</a>
<a name="hdng1"></a>
Raw flaxseed or flaxseed plant may increase blood levels of cyanide, a toxic chemical (this effect has not been reported when flaxseed supplements are taken at recommended doses). <a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> In theory, flaxseed may increase the effect of other medications that lower lipid (cholesterol and triglyceride) levels in the blood.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Human studies on the effect of flaxseed on blood sugar levels report mixed results. Flaxseed cannot be recommended as a treatment for diabetes at this time.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Several studies in humans report an increased risk of prostate cancer in men taking alpha-linolenic acid (which is present in flaxseed) by mouth.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> There is limited high quality research of the effects of flaxseed or alpha-linolenic acid (which is in flaxseed) on the risk of developing prostate cancer. This area remains controversial as there is some data reporting possible increased risk of prostate cancer with alpha linolenic acid.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Until more information is available, men with prostate cancer or at risk for prostate cancer should avoid flaxseed and alpha-linolenic acid supplements.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> One small study of men with prostate cancer reports that flaxseed supplements do not increase prostate specific antigen (PSA) levels.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Dietary flaxseed may increase the effects of tamoxifen, a medication used to treat cancer.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Goss PE, Li T, Theriault M, et al. Effects of dietary flaxseed in women with cyclical mastalgia.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> 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.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Lemay A, Dodin S, Kadri N, et al. Flaxseed dietary supplement versus hormone replacement therapy in hypercholesterolemic menopausal women.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
Early information from one study in women, the results of which have not been fully reported, suggests that flaxseed may reduce menstrual breast pain.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> The effects of flaxseed on blood glucose levels are not clear, although hyperglycemic effects have been reported in one case series.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Good studies that examine the effect of flaxseed on heart disease in humans are not available. It is unclear whether flaxseed supplementation alters the course of heart disease.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> There is a lack of information from human studies that flaxseed is effective in preventing or treating breast cancer.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> One study in humans suggests that flaxseed might lower blood pressure. The evidence in this area is not clear, and more research is needed before a recommendation can be made.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Use caution when combining flaxseed with other herbs or supplements that can lower blood pressure.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Individuals taking medications to lower blood pressure should use caution when taking flaxseed.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Drugs used by mouth should be taken one hour before or two hours after flaxseed to prevent decreased absorption. People taking mood stabilizers such as lithium should use caution.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Because of the laxative effects of flaxseed, caution should be used when it is taken with other supplements that have laxative effects.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Caution should be used when flaxseed products are taken with herbs and supplements that are believed to increase the risk of bleeding.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
In large doses, or when taken with inadequate water, flaxseed may precipitate bowel obstruction via a mass effect.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> 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.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Lignans are sometimes referred to as phytoestrogens and may possess estrogen-like properties. It is not known if flaxseed can alter the effects of birth control pills or hormone replacement therapies.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Flaxseed may stimulate menstruation or have other hormonal effects and could be harmful to pregnancy.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
Whole or bruised (not ground) flaxseed can be mixed with liquid and taken by mouth. Generally, 1 tablespoon in this form is mixed with 6 to 12 ounces of liquid and taken by mouth up to three times a day.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Anecdotally, 30-100 grams of flaxseed flour can be mixed with warm or hot water to form a moist compress and applied to the skin up to three times a day. It is not clear how long a flaxseed poultice should be used.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
People who have had a heart attack are reported to benefit from diets rich in alpha-linolenic acid, which is found in flaxseed.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Laxative effects are reported in several studies of people taking flaxseed or omega-3 acids. People with diarrhea, irritable bowel syndrome, diverticulitis, or inflammatory bowel disease (Crohn's disease or ulcerative colitis) should avoid flaxseed due to its possible laxative effects. Nausea, vomiting, and abdominal pain are reported in two individuals shortly after taking flaxseed products by mouth; these reactions may have been caused by allergy.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
Laxatives and stool softeners may increase or enhance the laxative effects of flaxseed.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Based on animal studies, overdose of flaxseed may cause shortness of breath, rapid breathing, weakness, or difficulty walking, and may cause seizures or paralysis.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Brooks JD, Ward WE, Lewis JE, et al. Supplementation with flaxseed alters estrogen metabolism in postmenopausal women to a greater extent than does supplementation with an equal amount of soy.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Mandasescu S, Mocanu V, Dascalita AM, et al. Flaxseed supplementation in hyperlipidemic patients.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
Large amounts of flaxseed by mouth may cause the intestines to stop moving (ileus).<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Use caution if combining flaxseed with other mood-altering herbs, including St. John's wort ( Hypericum perforatum ), kava ( Piper methysticum ), or valerian ( Valeriana officinalis ).<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Use caution when combining flaxseed products with supplements that may raise blood sugar levels.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> 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.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
Flaxseed contains alpha-linolenic acid, which may theoretically lower blood pressure.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
It has been proposed that alpha-linolenic acid, provided as flax oil capsules, may delay the timing of spontaneous delivery, but the available evidence does not support this use.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Preliminary evidence supports the idea that deficiencies or imbalances in certain highly unsaturated fatty acids may contribute to attention deficit hyperactivity disorder (ADHD). Based on one trial, alpha linolenic acid-rich nutritional supplementation in the form of flax oil may improve symptoms of ADHD. More research is needed to confirm these results.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Young GS, Conquer JA, Thomas R. Effect of randomized supplementation with high dose olive, flax or fish oil on serum phospholipid fatty acid levels in adults with attention deficit hyperactivity disorder.<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a> Joshi K, Lad S, Kale M, et al. Supplementation with flax oil and vitamin C improves the outcome of Attention Deficit Hyperactivity Disorder (ADHD).<a href="
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-flaxseed.html" TARGET="_blank"
[1]</a>
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NCCAM is funding studies on flaxseed. Recent studies have looked at the effects of flaxseed on high cholesterol levels, as well as its possible role in preventing conditions such as heart disease and osteoporosis. <a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Studies of flaxseed preparations to lower cholesterol levels report mixed results.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a>
This fact sheet provides basic information about flaxseed and flaxseed oil--common names, uses, potential side effects, and resources for more information.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Flaxseed should not be taken at the same time as any conventional oral medications or other dietary supplements. Tell your health care providers about any herb A plant or part of a plant used for its flavor, scent, or potential therapeutic properties.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> The fiber in flaxseed may lower the body's ability to absorb medications that are taken by mouth.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Whole or crushed flaxseed can be mixed with water or juice and taken by mouth.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Flaxseed, like any supplemental fiber source, should be taken with plenty of water; otherwise, it could worsen constipation or, in rare cases, even cause intestinal blockage.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Flaxseed is the seed of the flax plant, which is believed to have originated in Egypt. It grows throughout Canada and the northwestern United States.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a> Not enough reliable data are available to determine whether flaxseed is effective for heart conditions.<a href="
http://nccam.nih.gov/health/flaxseed/index.htm" TARGET="_blank"
[2]</a>
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