Flaxseeds contain omega-3 fatty acids -- specifically, alpha-linolenic acid -- which, in combination with dietary fiber and plant lignans, may help lower your cholesterol and your risk for heart disease, according to an article published in "Applied Physiology, Nutrition, and Metabolism" in October 2009. Flaxseeds are one of the best sources for this type of omega-3 fat, but they don't provide significant amounts of the important omega-3 fats EPA and DHA.
ALA Versus EPA and DHA
Your body must convert ALA to EPA and DHA before it can use it. This conversion isn't very efficient, so flaxseeds aren't as good a source of omega-3 fats as seafood, which contains EPA and DHA.
The Academy of Nutrition and Dietetics recommends getting between 1.3 grams and 2.7 grams of ALA each day for every 2,000 calories you consume. This is easy to do if you consume flaxseeds because just 1 tablespoon provides 2.4 grams of ALA. In comparison, a 3-ounce serving of salmon or herring contains about 1.8 grams of omega-3 fats in the form of EPA and DHA, which is more than three times the recommended minimum intake of 500 milligrams per day for EPA and DHA.