The omega-3 fatty acids found in deep-water fish oil, particularly DHA, are needed for normal nervous system function. It has been theorized that adequate long-chain PUFAs, especially DHA, may reduce the development of depression.

So important are essential acids in relations to depression that they even appear to decrease the risk of suicide. Investigators in one study found low levels of DHA and a high ratio of omega-6 fatty acids to omega-3 fatty acids predicted suicide risk in subjects with depression. According to the study's authors, "If confirmed, this finding would have implications for the neurobiology of suicide and reduction of suicide risk."

A number of studies have indicated that depressed people have lower omega-3 fatty acid levels than people who are not depressed. Moreover, low levels of EPA have correlated with increased severity of depression. Research has shown supplementation of EPA can be beneficial in the treatment of depression when administered alone.

A 2007 study at Haukeland University Hospital in Norway discovered that regular and long-term intake of omega-3 fatty acid-rich cod liver oil may protect people from symptoms of depression.205 The prevalence of depressive symptoms was 29% lower in regular cod liver oil users than the rest of the population.

Dietary sources of PUFAs, such as cold-water fish and flax seed are rich in essential fatty acids and can be protective against depression.

References
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