Do omega-3 fatty acid supplements have cardiovascular benefits?

According to a new US review, supplementation with omega-3 fatty acids may not be associated with a lower risk of cardiovascular disease (CVD) and all-cause mortality in patients after all. Experts have criticized the review as flawed. It will not change the current health recommendations by authoritative bodies such as the World Health Organization, recommending an adequate consumption of omega-3 fatty acids in order to maintain health and prevent age-related chronic diseases.

The review and meta-analysis included 20 randomized controlled trials evaluating the effects of omega-3 fatty acid supplementation on CVD in 68,680 adult patients at increased cardiovascular risk (1). The analysis showed no statistically significant association between the intake of supplements containing omega-3 fatty acids and a lower risk of all-cause mortality, cardiac death, sudden death, myocardial infarction, or stroke.

The researchers concluded that these findings do not therefore justify the use of omega-3 fatty acids as a structured intervention in everyday clinical practice or guidelines supporting dietary omega-3 fatty acid administration. An individual patient data meta-analysis would, however, be more appropriate in order to refine possible associations linked, among others, to dose, adherence, baseline intake, and CVD risk group.

Experts have criticized that the meta-analysis combined studies that were not comparable in their design: studies on healthy individuals were combined with those targeting cardiovascular patients already undergoing treatment with one or more cardioprotective drugs (e.g., statins), which may mask the less potent and more long-term effects of omega-3 fatty acids. In addition, the researchers apparently did not examine whether participants were sufficient or insufficient in their dietary intake of omega-3 fatty acids within each individual study included in the meta-analysis. Since all-cause mortality can be affected by many lifestyle factors apart from nutrition, it cannot necessarily be expected to find that omega-3 fatty acids alone will have a significant preventive effect.

The scientists further commented that consumers should not be swayed by the results. The study will not change the current recommendations by authoritative bodies such as the World Health Organization, American Heart Association and the US National Academy of Sciences, who recommend an adequate consumption of omega-3 fatty acids. While people should ideally be eating a diet high in fatty fish containing these nutrients, the reality is that many people do not do this. For these people, supplements can serve as an affordable and safe way to add omega-3 fatty acids to the diet.

Two previously published meta-analyses have shown positive correlations between increased intake of eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) and reduced cardiovascular risk (2). Increased consumption of omega-3 fatty acids from fish or fish-oil supplements has been shown to reduce rates of all-cause mortality, cardiac and sudden death, and possibly stroke (3).

1. Rizos, E. C. et al. Association Between Omega-3 Fatty Acid Supplementation and Risk of Major Cardiovas-cular Disease Events. Journal of the American Medical Association. Published online September 2012.
   
   
2. Mozaffarian, D. and Rimm E. B. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA. 2006; 296(15):1885–1899.
   
   
3. Wang, C. et al. n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review. Am J Clin Nutr. 2006; 84(1):5–17.