Fish Oils
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What is it?
Fish contain a type of oil called omega-3. Fish oils are also available in capsule form as a dietary supplement.
How does it work?
Polyunsaturated fats are important for brain function. The body uses fish oils in a person's diet to make these polyunsaturated fats.
Is it effective?
Countries with a low consumption of fish have been reported to have a higher rate of depression. Furthermore, some studies have found that depressed patients have a reduced amount of omega-3 in their blood. The reduced omega-3 could be either a cause or an effect of the depression.
Several studies have investigated the effects of fish oils when taken with antidepressant medication. In general, taking omega-3 supplements had a positive effect on depressive symptoms compared to placebo (dummy pill and antidepressants) when added to antidepressants.
However, the one study that tested omega-3 supplements as a single treatment for depression found no effect.
Are there any disadvantages?
None are known.
Where do you get it?
Fish oil capsules are available from supermarkets and health food shops. Eating a variety of fish 3-5 times per week will also give you a sufficient amount of omega-3.
Recommendation
There is no good evidence at present that taking fish oil supplements alone helps depression.
Key references
2008 Annual evidence update on CAM in depression: Diet and nutrition. Complementary and Alternative Medicine Specialist Library. National Library for Health. Available: http://www.library.nhs.uk/cam/ViewResource.aspx?resID=295244 [accessed 17 Nov 2008]
Appleton KM, Hayward RC, Gunnell D, Peters TJ, Rogers PJ, Kessler D. Effects on n-3 long-chain polyunsaturated fatty acids on depressed mood: systematic review of published trials 1-3. American Journal of Clinical Nutrition 2006; 84: 1308-1316.
Lin P-Y, Su K-P. A meta-analytic review of double-blind, placebo-controlled trials of antidepressant efficacy of omega-3 fatty acids. Journal of Clinical Psychiatry 2007; 68: 1056-1062.
Marangell LB, Martinez JM, Zboyan HA, Kertz B, et al. A double-blind, placebo-controlled study of the Omega-3 fatty acid docosahexaenoic acid in the treatment of major depression. The American Journal of Psychiatry 2003; 160: 996-999.
Williams AL, Katz D, Ali A, Girard C, Goodman J, Bell I. Do essential fatty acids have a role in the treatment of depression? Journal of Affective Disorders 2006; 93: 117-123.