SHEFFIELD, UNITED KINGDOM. There is considerable evidence that fish oils help in combating depression and other mental illnesses. What is not quite clear is whether it is eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) that is the most active component.
The standard medical therapy for depression involves the use of tricyclic antidepressants or selective serotonin reuptake inhibitors (SSRIs). These drugs, however, are not terribly effective. Prozac, for example, produces a 50% improvement in symptoms in only 38% of patients starting treatment. This is not much better than the placebo effect, which provides 50% improvement in about 25% of patients.
Other studies have examined whether supplementing with fish oils will raise EPA levels and improve symptoms of depression. A team of British and Scottish researchers has just completed a study aimed at determining if the ethyl ester of EPA, ethyl-eicosapentaenoate (EEP), would be effective in strengthening the beneficial effect of standard antidepressants. The study involved 60 patients who were already being treated with SSRIs or tricyclic antidepressants. Fourteen patients received a placebo while the remaining 46 received either 1, 2 or 4 grams/day of EEP. All participants were evaluated for depression using several different scales at the beginning of the experiment and after 12 weeks. At the end of the study it was clear that the 1gram/day dosage of EEP was highly effective in reducing depression and associated conditions such as sadness, pessimism, inability to work, sleep disturbances, and diminished sex drive. In most cases, 60- 70% of patients receiving 1 gram/day of EEP showed an improvement of 50% or better. This compares to only 25% of the patients on the placebo showing a 50% improvement. The degree of improvement was substantially less in the 2 grams/day and 4 grams/day groups. The researchers speculate that this could be due to the depletion of the omega-6 fatty acid, arachidonic acid, by an excess of omega-3 fatty acid (EPA), indicating that the balance between omega-3 and omega-6 is important when it comes to depression.
The researchers conclude that concurrent treatment with 1 gram/day of EEP is effective in reducing depression in patients who are still depressed despite treatment with standard medications. They are now planning on evaluating EEP on its own as a treatment for depression.
Peet, M. and Horrobin, DF. A dose-ranging study of the effects of ethyl-eicosapentaenoate in patients with ongoing depression despite apparently adequate treatment with standard drugs. Archives of General Psychiatry, Vol. 59, October 2002, pp. 913-19