New Review of DHA Omega-3 and Reduction of Cardiovascular Disease Risk Factors
Holub, BJ, Prostagl. Leuk. and EFAs, 81:199-204, 2009
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
The present publication represents a review of numerous population (epidemiological) and controlled clinical trials which have supported the beneficial effects of DHA omega-3 fatty acid from algal sources (devoid of EPA) as well as fish/ fish oils containing DHA as well as EPA. While numerous studies have indicated that higher intakes of DHA+EPA from fish and fish oils in long-term population studies are associated with a reduced risk of mortality due to cardiovascular disease, the resent review has focused upon the attenuating and beneficial effects of DHA supplementation on various risk factors associated with cardiovascular disease. A number of studies have shown that varying doses of algal DHA devoid of EPA can have significant beneficial effects on circulating levels of plasma lipids and lipoproteins. The blood triglyceride-lowering effect of DHA appears to be very similar to that of EPA or mixtures of DHA+EPA when compared at equivalent dosages and over similar durations of daily supplementation. Modest dosing with DHA (1000mg/day) over 8 weeks has been found to significantly decrease fasting triglyceride levels by an average of 22% in some reports. In the present review of the many studies published using algal DHA supplementation, the average dose (all studies combined) was 2092 mg DHA /day which provided an average lowering of fasting triglyceride levels of 17% along with a 6.4% rise in HDL-cholesterol levels. Recent studies have also shown the ability of DHA supplementation to lower postprandial triglyceride levels. Such a significant post – meal suppression in circulating triglyceride levels (which commonly surge at 4-6 hours following a meal containing simple carbohydrates + fat) is of interest in view of recent research indicating postprandial lipemia to be an important risk factor for cardiovascular disease. Other studies have indicated that higher levels of DHA (approaching 3-4 gm/day) can favorably attenuate other risk factors including resting heart rates and blood pressures to a moderate but significant degree.
Current daily intakes of DHA in the North American population approximate 80 mg/day along with an additional intake of long-chain omega-3 fatty acid as EPA approaching 30 mg/day. The American Dietetic Association in conjunction with the Dietitians of Canada have published a position paper (J. Am. Diet. Assoc., 107:1599-1611 (2007)) recommending a target daily intake of DHA+EPA of 500 mg/day for overall health and cardiovascular care for the general adult public. It is noted that the overall dietary ratio of DHA:EPA as consumed in mixed fish / seafood in a typical western diet is approximately 2.3:1.