(28-02-10) Increase Omega-3 Polyunsaturated Fatty Acids and Prevent Cardiovascular Disease

by Helmut Beierbeck,


Cardiovascular disease is a leading cause of death in the developed world. It is largely a lifestyle disease, and simple changes in diet and exercise can considerably lower the risk. One such simple change is an increase in the consumption of n-3 (omega-3) polyunsaturated fatty acids (PUFAs) (1). The authors of a 2009 article estimated that between 72,000 and 96,000 premature deaths could be prevented annually just in the U.S. alone by optimizing n-3 fatty acid levels (2). The importance of n-3 PUFAs in health and disease is readily acknowledged by mainstream health organizations. For example, the Nutrition Committee of the American Heart Association (AHA) has this to say about omega-3 fatty acids and cardiovascular disease (3): "Omega-3 fatty acids have been shown in epidemiological and clinical trials to reduce the incidence of cardiovascular disease. Large-scale epidemiological studies suggest that individuals at risk for coronary heart disease benefit from the consumption of plant- and marine-derived omega-3 fatty acids, although the ideal intakes presently are unclear. Evidence from prospective secondary prevention studies suggests that EPA + DHA supplementation ranging from 0.5 to 1.8 g/day (either as fatty fish or supplements) significantly reduces subsequent cardiac and all-cause mortality. For alpha-linolenic acid, total intakes of 1.5 to 3 g/day seem to be beneficial." One way in which n-3 fatty acids affect cardiovascular disease is by competing with n-6 fatty acids in the formation of a class of hormone-like substances collectively referred to as eicosanoids. These eicosanoids - prostaglandins, thromboxanes, and leukotrienes - mediate the body's response to injury such as free radical damage. Eicosanoids derived from the n-6 PUFA arachidonic acid (AA) initiate a much more virulent reaction than those synthesized from the n-3 PUFA eicosapentaenoic acid (EPA). It is the role of n-3 eicosanoids to prevent this healing response from getting out of hand and causing further tissue damage. This is clearly seen by looking at the EPA/AA content of cell membrane phospholipids, the immediate eicosanoid precursors. The lower the phospholipid-bound EPA/AA ratio in plasma cell membranes, i.e. the higher the AA content, the higher the death rate from coronary heart disease (4). Of course, we can make neither n-3 nor n-6 fatty acids; the most important dietary sources are the n-3 PUFA alpha-linolenic acid and the n-6 PUFA linoleic acid plus EPA and docosahexaenoic acid (DHA) from marine sources. Our dietary choices therefore determine the eicosanoid healing response and the risk of developing cardiovascular disease. Only small amounts of n-3 and n-6 PUFAs are needed for eicosanoid synthesis. Unfortunately, many of us carry large stores of n-6 fatty acids, and correspondingly larger amounts of n-3 fatty acids are required to balance the n-6 PUFA load. The large excess of n-6 PUFAs is mainly due to the excessive consumption of vegetable oils. Canola oil has the least unfavourable n-3/n-6 ratio at ~1 : 2. That ratio for soy oil is ~1 : 7; sunflower at ~1 : 20 and corn oil at ~1 : 80 are even worse. Peanut, coconut and safflower oils contain n-6 PUFAs but no n-3 PUFAs at all (5). The best way to balance n-3 and n-6 eicosanoids is to both minimize the consumption of vegetable oil and increase the intake of n-3 fatty acids, preferably through fish consumption or EPA/DHA supplements rather than relying on EPA synthesis from alpha-linolenic acid. It is an inexpensive and effective way to reduce the risk of cardiovascular disease.

Sources: Jung UJ, Torrjon C, Tighe AP, Deckelbaum RJ. n-3 Fatty acids and cardiovascular disease: mechanisms underlying beneficial effects. Am J Clin Nutr 2008;87(suppl):2003S-2009S. http://www.ajcn.org/cgi/reprint/87/6/2003S Danaei G, Ding EL, Mozaffarian D et al. The preventable causes of death in the United States: Comparative risk assessment of dietary, lifestyle, and metabolic risk factors. PLoS Medicine April 2009;6(4) http://dx.doi.org/10.1371/journal.pmed.1000058 Kris-Etherton PM, Harris WS, Appel LJ. Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Circulation 2002;106:2747-2457. http://atvb.ahajournals.org/cgi/reprint/23/2/e20 Lands WEM, Diets could prevent many diseases. Lipids 2003;38(4):317-321. http://www.springerlink.com/content/v2658751u8q11261/fulltext.pdf Essential fats in food oils. http://efaeducation.nih.gov/sig/esstable.html

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