WASHINGTON, DC. On a worldwide basis more working days are lost to depression than to any other illness. The incidence of depression is growing with people born within the last 50 years being twice as likely to suffer from it than were their parents. Dr. Joseph Hibbeln of the National Institutes of Health believes that the reason for the increase in depression can be directly attributed to a major shift in dietary patterns, specifically fat intake. He points out that the vast increase in the use of soy, corn, palm and cottonseed oils in the last 100 years has totally changed the traditional ratio of omega-6 to omega-3 fatty acids in the diet. Soy oil consumption in the US, for example, has increased thousand-fold in the last 100 years helping to skew the omega-6 to omega-3 ratio from about 1:1 to today's 16:1. This, Dr. Hibbeln believes, spells trouble. The brain consists pretty well entirely of fat so clearly one's fat intake could affect one's brain composition, particularly the ion channels which channel signals in and out of the brain. There is also evidence that low levels of omega-3 fatty acids are associated with low levels of the mood hormone serotonin. Dr. Hibbeln's hypothesis is supported by the fact that the incidence of depression is considerably lower in countries with a high fish consumption.
Fish, particularly fatty ocean fish, is an excellent source of omega-3 fatty acids and its frequent consumption would help to nudge the ratio back towards the optimum 1:1. At least three clinical trials have observed a marked improvement in depressed patients given relatively high doses of fish oils. This has spurred other scientists to look closer at the potential benefits of fish oil supplementation. At the moment there are at least 10 clinical trials underway evaluating fish oils in the treatment of depression, attention deficit disorder, and schizophrenia.
Small, Meredith F. The happy fat. New Scientist, August 24, 2002, pp. 34-37