In a meta-analysis of 15 randomized, double-blind, placebo-controlled studies, researchers from the University of Illinois at Chicago, led by John M. Davis, M.D., research professor at the University of Illinois at Chicago and ACNP member, found that patients taking omega-3 with either EPA or a combination of EPA and DHA experienced clear antidepressant benefits. However, across studies, patients taking the pure DHA form of omega-3 saw no antidepressant effect.
"Our analysis clarifies the precise type of omega-3 fatty acid that is effective for people with depression and explains why previous findings have been contradictory," said Davis. "The EPA predominant formulation is necessary for the therapeutic action to occur. The DHA predominant formulation does not have antidepressant efficacy."