Food and Behaviour Research

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Importance of the ratio of omega-6/omega-3 essential fatty acids: evolutionary aspects

Simopoulos, A.P. (2003) World Rev Nutr Diet.  92 1-22. 

Web URL: View the PubMed link for this article here


Review article - no abstract available.


This article provides a review of the scientific evidence linking changes in the dietary ratio of omega-3 to omega-6 fatty acids to variations in patterns of human health and disease. It provides an editorial and introduction to a whole issue of the World Review of Nutrition and Dietetics devoted to this important topic.

The available information suggests that human beings evolved on a diet containing roughly equal proportions of omega-3 and omega-6 fatty acids. By contrast, modern Western diets typically have an omega-6 to omega-3 ratio of more than 15 to 1.

Evidence suggests that this excess of omega-6 fatty acids relative to omega-3 is a risk factor for many physical diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases. Lower dietary ratios of omega-6 to omega-3 have been shown to exert protective effects, although the optimal ratio may vary for different diseases or conditions.

An omega-6 to omega-3 ratio of around 4:1 has been found particularly beneficial for brain-mediated functions in some studies. A similar ratio - achieved by modelling the traditional diet of Crete - was also associated with a 70% reduction in mortality in trials aimed at the secondary prevention of cardiovascular disease.

Other papers reviewed here concern the implications of dietary omega-6 / omega-3 balance for some forms of cancer and for inflammatory conditions such as rheumatoid arthritis.

This paper - together with the expert collection for which it forms an introduction - will provide an ideal reference point for anyone interested in the medical and other evidence for the crucial importance of omega-3 relative to omega-6 fatty acids in human health and disease.