Nutritional perspectives on benefits of fish consumption

Since early observations were made in the 1950's and cross-cultural comparisons reported in the 1970's, evidence has accumulated with regard to the beneficial role of fatty acids derived from fish (fin-fish and shell-fish) for a wide range of health outcomes. The one for which the most evidence has accumulated is cardiovascular diseases (CVD). In the case of CVD, the relationship is strongest for fish derived very long chain omega-3 fatty acids, eicosapentaenoic acid (EPA,20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), rather than plant derived omega-3 fatty acid, alpha linolenic acid (ALA, 18:3n-3). Potential mechanisms include inflammation, platelet aggregation, hypertension, lipoprotein profiles (triglyceride and high density lipoprotein cholesterol concentrations) and vasoconstriction/dilation. These effects are thought to be mediated through alternations in fatty acid composition of cell membrane phospholipid, gene expression, eicosanoid synthesis and lipoprotein production rates, although additional mechanisms may be involved. The majority of evidence suggests that dietary EPA and DHA are associated with reduced risk of coronary heart disease death but not sudden death. Nonetheless, there is considerable controversy in data interpretation. Discrepancies can be attributed to differences in study designs, participant characteristics, intervention and confounding variables such as background diet, and amount, duration and composition of omega-3 fatty acid supplements. Current recommendations are for individuals to consume at least two fish meals per week, preferably ‘oily' fish. In addition to the EPA and DHA content, fish can displace foods high in saturated fat from the diet (fats of animal origin) which can have an independent effect on CVD risk.