The omega-6/omega-3 ratio and cardiovascular disease risk: uses and abuses.

The cardioprotective effects of omega-3 fatty acids (n-3 FAs) are well known, but the role that the n-6 FAs play in coronary heart disease is unclear. These two classes of essential FAs compete for a number of enzyme systems, and their metabolites can powerfully influence (often in different directions) inflammatory responses, vascular reactivity, and platelet aggregation. Accordingly, the n-6/n-3 FA ratio may be of value in interpreting biomarker data and in making nutritional recommendations. Although initially appealing, there are few human experimental and clinical trial data to support this view. This paper reviews a variety of studies that, in the aggregate, suggest that the ratio is, both on theoretical and evidential grounds, of little value. Metrics that include the n-3 FAs alone, especially eicosapentaenoic and docosahexaenoic acids, appear to hold the greatest promise.