Health benefits and concerns

Cancer (Prostate)

Alpha-linolenic acid is a fatty acid found in many foods. Most, but not all, studies have found that high dietary or blood levels of alpha-linolenic acid correlate with an increased risk of prostate cancer. Concentrations of alpha-linolenic acid are high in almonds, Brazil nuts, cashews, flaxseeds, hazelnuts, macadamia nuts, peanuts, pecans, pine nuts, pistachios, and walnuts.

Constipation

Flaxseed is a bulk-forming laxative. It has a high fiber and mucilage content that expands when it comes in contact with water. As the volume in the bowel increases, a reflex muscular contraction occurs, stimulating a bowel movement. This mild laxative is best suited for long-term use in people with constipation.

High cholesterol

Flaxseed, like other good sources of soluble fiber, has been reported to lower cholesterol. A recent trial found that partially defatted flaxseed containing 20 grams of fiber per day significantly lowered LDL cholesterol, suggesting that at least one of the cholesterol-lowering components in flaxseed is likely to be the fiber in this product (as opposed to the oil removed from it). In a preliminary trial, young women who had normal cholesterol levels took 50g (approximately 1–3/4 oz.) of raw flaxseed per day for a month, either as flour or baked into bread, which resulted in a 9% decrease in total cholesterol and an 18% decrease in LDL (“bad”) cholesterol.

Doctors and researchers are interested in alpha-linolenic acid (ALA)–the special omega-3 fatty acid found in large amounts in flaxseeds and flaxseed oil. ALA is a precursor to EPA, a fatty acid (obtained in nature from fish oil) that is believed to protect against heart disease. To a limited extent, ALA converts to EPA in the body. However, unlike EPA, ALA does not lower triglyceride levels (a risk factor for heart disease). Preliminary research on the effects of ALA from flaxseed has produced conflicting results. For example, ALA has improved parameters of blood vessel health that should protect people from heart disease, yet ALA may cause damage to LDL cholesterol. Such damage is believed to be a precursor to heart disease.

Lupus

Foods high in omega-3 fatty acids, such flaxseed, may decrease lupus-induced inflammation. In one trial, nine people with kidney damage due to SLE were fed increasing amounts of flaxseed for a total of 12 weeks. After examining the results, researchers concluded that 30 grams per day was the optimal intake for improving kidney function, decreasing inflammation, and reducing development of atherosclerosis. Flaxseeds also contain antioxidants, potentially helpful to those with lupus.

Menopause

Soybeans contain compounds called phytoestrogens that are related in structure to estrogen, though the estrogenic activity of soy is quite weak according to some reports. Soy is known to affect the menstrual cycle in premenopausal women. Researchers have linked societies with high consumption of soy products to a low incidence of hot flashes during menopause. In one double-blind trial, 60 grams of soy protein caused a 33% decrease in the number of hot flashes after four weeks and a 45% reduction after 12 weeks. However, in further analysis of the data in this trial, researchers now believe constituents in soybeans other than phytoestrogens must have been responsible for the therapeutic effect. In one randomized trial, high intake of phytoestrogens from soy and flaxseed reduced both hot flashes and vaginal dryness, but much (though not all) of the benefit was also seen in the group not taking the supplements. As a result of these studies, doctors often recommend that women experiencing menopausal symptoms eat tofu, soy milk, tempeh, roasted soy nuts, and other soy-based sources of phytoestrogens. Soy sauce contains very little phytoestrogen, and many processed foods made from soybean concentrates have similarly low levels of phytoestrogens. Flaxseed (as opposed to flaxseed oil) is also a good source of phytoestrogens.

Health benefits and concerns for nuts and seeds
Many health benefits and concerns associated with this food are applicable to other nuts and seeds. Read about health benefits and concerns for nuts and seeds for a full description.