Herbs & Supplements

Who is this for?

Uses

Note: Only flax products that are packaged specifically for food or medical use should be taken by mouth. Flaxseed sold for planting and flaxseed oil sold for painting or other purposes are not suitable for human consumption. Products labeled as "linseed oil" should never be taken by mouth.

Today, one major use of flaxseed is as a laxative. Because flaxseeds are coated with mucilage, a natural gummy substance that does not dissolve in water, they form a thick, gooey mass when exposed to fluids. The body does not digest mucilage, so the resulting large soft mass moves through the intestines and also triggers intestinal muscle contractions. In addition, the mucilage forms a slick coating on the walls of the intestines. All of these effects help to prevent or relieve constipation. Flaxseed oil may also be taken by mouth for a mild laxative effect. Both flaxseeds and flaxseed oil may also be used to treat other gastrointestinal complaints such as irritable bowel syndrome.

Historically, however, flaxseed has been used to treat a number of conditions including heart disease. In the last 20 years or so, interest in the possible effects of flaxseed products on the heart has been renewed, somewhat. Research has been done to test the effectiveness of flaxseed and flaxseed oil in reducing high blood pressure and high cholesterol. In a 12-week long study of 59 men with high blood pressure, those taking 8 grams of flaxseed oil per day saw significant reductions in blood pressure compared to men who took safflower oil. Generally, in animal studies and small human studies, flaxseed produced at least modest reductions in total cholesterol, triglycerides, and/or low-density lipoproteins (LDL), the "bad" type of cholesterol. In some studies, though, decreases were not significant or blood levels of high-density lipoproteins (HDL), the "good" type of cholesterol also decreased. Separate animal studies showed a small decrease in blood pressure. However, these results have not been confirmed in larger human studies.

Flaxseed was thought to possess some anti-estrogenic effects, which have been studied for possible protection against certain types of breast cancer and prostate cancer. However, when these effects were tested in several laboratory studies and a few human studies, the results were inconclusive. In some of the studies, flaxseed products appeared to prevent or delay cancer, while in other research the incidence and/or progression of cancer seemed to be increased, suggesting that flaxseed may actually have estrogen-like effects. Other herbal products with estrogenic properties have been used by men to lessen benign prostate enlargement and by women to relieve menstrual cramps and symptoms of menopause. For example, when 30 postmenopausal women took 40 grams of crushed flaxseeds per day for 6 weeks, the incidence and severity of hot flashes decreased by about 50% in one study. Estrogenic herbals may also prevent or treat osteoporosis for both men and women. At least one study of laboratory animals has shown that flaxseed in the diet may reduce the amount of chromosome damage that may be caused by cancer, but not enough is known about the cause of chromosome damage or its prevention to recommend flaxseed for cancer prevention. Additional studies are underway to assess further the possible effects of flaxseed and flaxseed oil on breast and prostate cancers, menopausal symptoms, osteoporosis, and chromosome damage.

More recently, flaxseed has been studied for its potential to prevent kidney damage in individuals who have an autoimmune condition known as systemic lupus erythematosus (SLE). Some evidence from animal studies and human case reports supports the use for SLE, but more studies are needed before flaxseed can be recommended for this use.

Flaxseed oil can be applied topically to soften dry skin. Also for topical use, a poultice can be made by mixing whole or crushed flaxseed with about three times as much hot water as the amount of flaxseed and then letting the mixture stand until it makes a thick gel. A soft cloth is then covered with the gel, possibly heated, and applied to an aching or injured area of skin surface.