Omega 3 fatty acids that contain mostly eicosapentaenoic acid (EPA) are useful adjuncts to antidepressants in patients with depression, a large Australian study suggests.

The finding is the strongest from the review of 33 meta-analyses comparing various dietary supplements with placebo in patients with or at high risk of mental illness, researchers from Western Sydney University say.

Other supplements including high-dose methylfolate, N-acetyl cysteine and vitamin D may also be useful adjuncts in treatment of some psychiatric disorders, although more research is needed, they say.

Here are their key results: