If you're searching for ways to protect your heart, you've probably heard about the benefits of fish and fish oil supplements containing omega-3 fatty acids.
Alpha-linoleic acid (ALA), another omega-3 polyunsaturated fatty acid, is present in several plant sources including walnuts, flaxseed oil, and canola oil. Flaxseed oil is a popular supplement being sold to prevent heart disease. Does ALA have the same benefit as fish and fish oil supplements?
Fish and fish oil supplements contain two omega-3 fatty acids: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). People can convert ALA to DHA and EPA and thus help to prevent cardiovascular disease, according to some experts.
But the small quantities of DHA and EPA the human body can make from ALA are much less than can come from eating fatty fish like salmon, tuna (fresh only), sardines, and mackerel.
Does ALA provide cardiovascular benefits in other ways? Despite many studies, reports, and recommendations, we don't have a clear answer.
Several large studies have suggested that people who consume higher amounts of ALA in foods are better protected against heart attacks. This may be one reason for the proven heart benefits of the Mediterranean diet, which contains many foods rich in ALA. But this diet also has other heart-healthy features that may account for its benefits.
Other studies, however, found no beneficial effects when large amounts of ALA were added to the diet. Unlike fish oil supplements, ALA supplements don't lower triglyceride levels. And an analysis of 14 studies found no beneficial effects of ALA supplements on blood pressure, total cholesterol, or LDL cholesterol.
Another 2006 review of research on ALA concluded that increased consumption of omega-3 fatty acids from fish or fish oil supplements, but not of ALA, reduced the risk of death from heart attacks and possibly from stroke.
Flaxseed oil supplements are heavily advertised on the Internet and many people take them as a source of ALA. Though dietary recommendations from the American Heart Association in 2002 stated that ALA intakes of approximately 1.5 to 3 grams per day "seem to be beneficial," no mention of ALA was made in the group's more recent 2006 dietary recommendations.
Flaxseed oil supplements are undoubtedly safe. Nonetheless, I'm not enthusiastic about taking flaxseed oil to prevent heart attacks. But then I am generally opposed to taking any supplement that is not fully proven to deliver its advertised benefits.
