Various studies in recent times have shown no relationship between depression and heart disease. An excellent explanation of these conflicting results is the difference in polyunsaturated fatty acid intake between the different groups. For instance, in one study conducted in Finland, lower serum cholesterol was associated with lower mortality due to accidents and violence in coastal, fish-eating residents, but not among inland residents. Coldwater fish are an excellent source of long-chain polyunsaturated fatty acids like docosahexaenoic acid (DHA).
Historically, post-evolutionary human beings consumed a diet that achieved a balance between omega-6 and omega-3 fatty acids. Today, however, the average individual consuming a Western diet is deficient in omega-3 fatty acids due to excessive intake of corn, sunflower, safflower, cottonseed, and soybean oils rich in omega-6 fatty acids and decreased consumption of omega-3 rich foods such as salmon and tuna.
Historically, post-evolutionary human beings consumed a diet that achieved a balance between omega-6 and omega-3 fatty acids. Today, however, the average individual consuming a Western diet is deficient in omega-3 fatty acids due to excessive intake of corn, sunflower, safflower, cottonseed, and soybean oils rich in omega-6 fatty acids and decreased consumption of omega-3 rich foods such as salmon and tuna.
During human evolution, ratios of n-6 to n-3 fatty acids were approximately 1:1, but are now estimated to be between 10:1 to 25:1.
