Antidepressant effect of omega-3 fat appears to depend on the specific type of omega-3 fat used

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Fish is sometimes described as ‘brain food’ – why? Well, at least part of the explanation may rest in the fact the certain types of fish are rich in so-called omega-3 fats that appear to have benefits for the brain. There is some evidence, for instance, which suggests that omega-3 fats can normalise brain function and protect against certain mental disorders including psychotic illness (see here for more about this) and depression.

There are two principle omega-3 fats found in fish: eicospentaenoic acid (EPA) and docosahexaenoic acid (DHA). Recently, scientists have attempted to unpick which, if any, of these two major fats gets the nod in terms of antidepressant action. Researchers based in Cambridge recently reviewed 28 placebo-controlled studies (the gold standard of studies for determining if a treatment works of not) in which omega-3 fats were used in the treatment of depression [1].

Some of the findings from this review include the facts that, generally speaking, omega-3 supplements were more effective when:

• treating major depression and bipolar depression over milder forms of depression

• the omega-3 supplements were used as an adjunct to other treatments rather than being the sole treatment

• the omega-3 was used to treat depression, rather than prevent it

Additionally, a major focus of this study was whether which, if any, of EPA or DHA appears to have the most potential as an antidepressant.

The results of this analysis showed that when EPA was the sole or main omega-3 fat used there was evidence of significant anti-depressant action. The same, however, was not true for DHA: in studies where DHA was the sole or main omega-3 supplement, no significant antidepressant action was found.

The authors of this review call for larger, well-designed studies of sufficient length to be performed, but at this stage the results suggest that if it’s mood enhancement we’re looking for, EPA gives more bang for our buck.


1. Martins JG, et al. EPA but not DHA appears to be responsible for the efficacy of omega-3 long chain polyunsaturated fatty acid supplementation in depression: evidence from a meta-analysis of randomized controlled trials. J Am Coll Nutr 2009;28(5):525-42

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