Increased intake of omega-3 fatty acids have been shown to alleviate symptoms of depression. The optimum omega-6 to omega-3 ratio is 1:1. But because omega-6 is abundant in processed foods (while the primary dietary source of omega-3 is fish) the omega-6 to omega-3 ratio of a typical American diet is by some estimates more like 20:1; a ratio that’s been linked to a wide range of chronic health problems.
A Dutch research team out of Rotterdam recruited more than 260 subjects with symptoms of depression, and about 460 randomly selected control subjects. A blood sample was taken from each subject. In their analysis of the samples, researchers found what they called a “direct effect of fatty acid composition on mood.” Subjects with depressive disorders had a significantly higher ratio of omega-6 to omega-3 fatty acids compared to subjects who were not depressed.
Walnuts and flaxseed contain alpha-linolenic acid, which is converted to omega-3 in the body. But only fish contains both omega-3s – eicosapentaenoic acid (EPA) and docohexaenoic acid (DHA). Salmon, tuna, swordfish, lake trout, herring, mackerel, and sardines are all good sources of EPA and DHA . The drawback with fish is the potential for mercury contamination when dark-meat fish (such as tuna and swordfish) is eaten several times each week.
In my opinion, supplements of fish oil (EPA-DHA 720 by Metagenics) provide an easy way to ensure a good intake of omega-3 fatty acids. Mercury content: zero. I recommend at least 2-3 grams per day for depression. When clients are under my direct supervision I add other specific supplements for individual needs.