When the goal of psychiatric treatment is full remission of depression and other mood disorders, we must be open to the idea of using complementary and alternative medicine, as long as there is scientific evidence that they work.
Omega-3 fatty acids, the active ingredients of those large, translucent fish oil capsules available in all drugstores, are an option that have been subjected to scientific scrutiny, and passed the test in some circumstances.
Fish oil contains 2 types of omega-3 fatty acids: Eico-sa-penta-enoic Acid (EPA) and Doco-sa-hexa-enoic Acid (DHA). When scientifically conducted studies of omega-3's are reviewed, the findings are mixed, but tend to show low-dose EPA (1000 mg/day is considered low dose when we are talking omega-3's) working for mood disorders. Studies of combinations of EPA and DHA tend to show favorable results for the combination when EPA dose in the combination is higher than DHA, with no benefit over sugar pill when DHA is higher than EPA.
Also, when low doses have been compared with high doses (EPA up to 4000 mg/day), it is the lower doses that have shown greatest improvement over sugar pills. Doses up to 9000 mg/day of omega-3s have been studied, with most of the evidence in favor of lower doses.
Most studies of omega-3's have tried to answer the question,"Do omega-3 fatty acids help antidepressants work better?" That is, they try to understand the potential of omega-3's as add-ons to antidepressants. However, there has been at least one study in which EPA alone (1000 mg/day) was compared with Prozac (20 mg/day) in the treatment of Major Depression and found to work just as well, with the combination of the Prozac and EPA working better than either one alone.
Potential benefits of using omega-3's in depression is that they have relatively few side-effects. There is a theoretical increased risk of bleeding, making caution necessary when a person taking them must undergo even minor operations (e.g. tooth extraction) or when that person must take blood thinners for other reasons.
One significant weakness of the studies of omega-3's as compared to those of prescription antidepressant medications is that these studies involve fewer patients - and generally speaking, confidence in the findings of a scientific study increases as the number of enrolled patients increases.
So what is a reasonable role of omega-3 fatty acids in the treatment of depression? Those who suffer from treatment-resistant depression should discuss the pros and cons of adding EPA 1000 mg/day to their medication regimen with their treating physician, and make sure that if they take a combination EPA/DHA pill, it has more EPA than DHA.