Several randomized controlled trials have been performed utilizing omega-3 fatty acids as a monotherapy for depression, or as augmentation therapy (added to an antidepressant for major depressive disorder.)  Two recent meta-analyses aggregated these data, and found that there is evidence for an anti-depressant effect of omega-3 fatty acids when used in conjunction with anti-depressant medications for depression; however, there was evidence of publication bias in favor of positive studies.  That is, a normal distribution of the effect sizes showed an absence of small, negative studies that have been published.  The available evidence from randomized controlled trials is modest, but does support a role for omega-3 fatty acids as an augmentation therapy for depression.  However, randomized controlled trials do not at this time support a role for omega-3 fatty acids in monotherapy for major depressive disorder, nor for boosting “subclinical depression” (which is to say depressed mood that does not meet the criteria for major depressive disorder.)

Problem with Randomized Controlled Trials

All of these studies involve very short time courses (e.g. supplementation over the course of approximately twelve weeks.)  The epidemiological data suggests that it is the overall consumption of omega-3 fatty acids over years to a lifetime that has a protective effect.  None of our randomized controlled trials are done over a long enough time period to determine the full effect of omega-3 fatty acids on mood.

Conclusion: Omega-3 Fatty Acids Have a Protective Effect

It is important to aggregate the evidence across a range of different types of studies, including epidemiological, cellular and molecular in addition to randomized controlled trials.  When that is done, the potential effect of Omega-3 fatty acids on depression and other mood disorders looks to be far greater than the available evidence from randomized, controlled trials.  As the Committee on Research on Psychiatric Treatments of the American Psychiatric Association recently concluded, “The preponderance of epidemiologic and tissue compositional studies supports a protective effect of omega-3 EFA intake, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).”

Hints from Humans that Turmeric Protects Memory

One provocative report from the  American Journal of Epidemiology in 2006 suggests that increased curry consumption in human populations is associated with a lowered risk for developing cognitive impairment, including memory loss, as one ages. Although this was a retrospective study using a population from Singapore these results are exciting, in part since most curries in Singapore are yellow curries which contain turmeric. Therefore, there is evidence that consuming turmeric prevents memory loss. In fact, people who ate curry “often” (once a month or more) were nearly half as likely to have cognitive impairment than were people who ate curry “rarely” (once every 6 months). Though more research needs to be done, these are encouraging results.