Philip J. Goscienski, M.D.
August 2009
Omega-3 fatty acids are probably the most important nutrients that are lacking in the Western diet. They are critical for normal brain and eye development during infancy. All through life omega-3 fats maintain normal function in almost every cell of the body. They help to prevent abnormal rhythms during a heart attack and they limit the progression of osteoporosis as we age.
The best sources of omega-3 fats are coldwater fish. The smaller ones such as wild salmon and sardines have high yields without the risk of mercury and other toxins. That's not where Stone Agers got omega-3 fatty acids half a million years ago or where hunter-gatherers find them today. The former didn't know how to fish until about 150,000 years ago. The latter may not have access to fish but plants have always been around.
The best plant sources of omega-3 fats are the green leafy ones. Nutritionists point to flax as a good source because it has a fairly high amount of alpha linolenic acid (ALA, also known as LNA), a precursor of DHA and EPA (docosahexaenoic acid and eicosapentaenoic acid). Fish are better sources of DHA and EPA than flax and green leafy plants.
Americans, especially the youngest ones, are notorious for their avoidance of vegetables. About a quarter of adults rarely have anything but lettuce, tomatoes and French fries, whose omega-3 content is just about zero.
You can get your omega-3 fats from flaxseeds or flax oil but flax fans have to work at getting as much as they need. Whole seeds are edible but it takes grinding to make them digestible. Flax at high doses interferes with some prescription medications and persons who eat more than 3 or 4 tablespoons of raw seeds a day put themselves at risk of thyroid enlargement. Flax oil is convenient but it tends to get rancid fairly quickly. All flax products should be refrigerated.
Although the ALA in flaxseed is a valuable nutrient it faces a biochemical bottleneck in the human body. The enzyme that converts ALA to EPA and DHA is rate-limited, that is, it requires large amounts of flax oil to yield the DHA and EPA that we need. It is barely 10 percent for EPA and even less for DHA.
The bottom line is that flax oil, whether it comes from seeds or in a bottle, is an excellent nutrient but it needs to be augmented by fish oil.
Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.