Researchers have been studying the effects of omega-3 fatty acids on mental health for quite some time. As the Harvard Health Blog notes, this is because “depression appears less common in nations where people eat large amounts of fish,” which contains significant amounts of omega-3s.

After dozens of clinical trials and meta-analyses looking at the results of those studies, there are some promising — though not definitive — results. Per the blog:

• The most effective omega-3 preparations used in studies seem to have at least 60 percent eicosapentaenoic acid (EPA) relative to docosahexaenoic acid (DHA).
• DHA seems to be less effective for depression than EPA, but may help protect against suicidal thoughts.
• Depressed overweight people with elevated inflammation in particular may benefit from EPA treatment.
• People with bipolar depression should be careful using omega-3s, as they (like many antidepressant medications) can induce mania.
• There is not enough evidence to recommend using omega-3s to treat conditions such as “schizophrenia, borderline personality disorder, obsessive compulsive disorder, and attention deficit disorder.”

The bottom line, though, is that there are no clear answers yet about how to treat mental health issues with omega-3s: “Omega-3 fatty acids are promising natural treatments for mood disorders, but we need more research about how they work, how effective they really are, and their long-term safety before we can make conclusive recommendations for people managing mental health conditions or who wish to improve mood.”