From The July 2004 Issue of Nutrition Science News
Much has been written about the cardiovascular, anticancer and immune-modulating effects of omega-3 oils found in cold-water fish. The main fatty acids in this family are alpha linolenic acid (ALA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). DHA and EPA, found predominantly in fish, appear to have most of the beneficial effects attributed to omega-3 oils, although the body can convert ALA to both DHA and EPA.
This conversion, however, is not always predictable or efficient. Even in the best circumstances, most ALA is used for energy and only a fraction is converted. Figures I've seen suggest that only 10 percent of ALA is converted to EPA and even less to DHA. Foods high in ALA are certainly still worthwhile, but fish oils have the advantage of containing preformed DHA and EPA. The only vegetarian source of preformed DHA I am aware of is extracted from marine mircroalgae.
A number of vegetable oils contain significant amounts of ALA. The most well-known is flaxseed, which contains approximately 55 percent ALA. Flaxseeds can be ground and put on cereal or in a shake. They contain more than 20 percent ALA by weight and are a good source of omega-3. Although flaxseed is increasingly found in breads and baked goods, I prefer to eat flaxseed ground and raw, since heating flaxseed may affect its ALA content.
A few common oils with relatively abundant levels of ALA are easily incorporated into salad dressings. Nonhydrogenated soybean oil contains 5 to 10 percent ALA, canola oil contains up to 14 percent, and walnut oil is about 14 percent. Oils with some of the highest levels of ALA are not generally available in the United States; perilla oil, derived from the seeds of the mint plant (Perilla ocimoid), contains 60 percent ALA and can be found in Asian specialty stores. 
I'm concerned by the trend in the oilseed industry to genetically engineer low-ALA vegetable oils to increase their stability. In my clinical practice, I saw many people who suffered from low omega-3 fatty acid levels. If low-ALA oils become the predominant oils in our diet, this will exacerbate what I think is already a significant problem.
Dan Lukaczer, N.D., is director of clinical services at the Functional Medicine Research Center, a division of HealthComm International Inc., in Gig Harbor, Wash
1. Haumann B. Alternative sources for n-3 fatty acids. Inform 1998;9(12):1108-19
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