Flaxseed oil improves blood omega-3 fatty acid concentrations.

Flaxseed oil is known to be a source of alpha-linolenic acid, an omega-3 fatty acid that can be converted to another omega-3 fatty acid called eicosapentaenoic acid (EPA) and that may reduce the risk of death from heart disease. Questions have been raised about how efficiently this conversion occurs and whether people who do not eat fish (a good source of EPA) can rely on flaxseed oil and other sources of alpha-linolenic acid being converted to EPA. A recent study gave 49 African-American subjects either capsules containing 3 grams of alpha-linolenic acid from flaxseed oil or capsules containing olive oil. After 12 weeks, blood levels of EPA increased by 60 percent in the group receiving flaxseed oil but did not increase in the group receiving olive oil. This study suggests that a significant increase in blood EPA levels can occur with a relatively low dose of flaxseed oil. The researchers conclude that it is very possible to get 3 grams of alpha-linolenic acid from diet without having to use dietary supplements. Flaxseeds, canola oil, soybean oil, and walnuts are other good sources of alpha-linolenic acid.

Harper CR, Edwards MJ, DeFilipis AP, Jacobson TA. 2006. Flaxseed oil increases the plasma concentrations of cardioprotective (n-3) fatty acids in humans. J Nutr 136:83-87.