There’s a reason fish oil capsules and other omega-3 supplements are so popular. “Omega-3 fatty acids are involved in many different fundamental [brain] processes,” says Simon Dyall, a principal academic and head of nutrition at Bournemouth University in the UK.

Omega-3 polyunsaturated fatty acids—namely EPA and DHA—and their metabolites influence gene expression, oxidative stress, cerebral blood flow, levels of neurotransmitters, and other brain-related processes such as the production of new neurons, Dyall explains. DHA in particular is an essential building block of the brain’s cell membranes. So at a molecular level—like a house without bricks or walls—the brain could not exist without omega-3 fatty acids.

There seems to no downside to eating more fish, with omega-3 fatty acids are uniquely high in fish, with a typical portion of salmon providing 2.5 to 3.5g. There is no official daily recommendation, but 250-500 mg is "recommended".

Before relying on supplements, it might be worth considering that something else in fish is also, or in combination [with omega-3’s], having some benefit.

If you want to double down on omega-3 and take a supplement along with your weekly portions of fish, the NIH states that the potential side-effects are mild. Just be sure to keep your supplement intake below 2 grams per day to avoid potential (though unlikely) health complications—including reduced immune function or increased bleeding, the NIH warns. (Ask your doctor first if you’re on prescription meds—especially blood thinners.)

So should you be taking an onega-3 supplement? Maybe, but look at your weekly fish consumption first.

See Time Magazine Article 20 Jun 2018