Omega-3 fatty acids

What they are

Omega-3 fatty acids, found in fish oil, are long-chain fats built into the membranes of brain cells. They also dampen inflammation.¹ They were tested in young people at high risk of psychosis, who have mild or brief psychotic symptoms but not a full psychotic illness, to see whether they could prevent one.

How well they work

The first trial, in Vienna, was strikingly positive. Of 81 young people at high risk, those who took omega-3 for 12 weeks developed psychosis far less often within a year: 2 of 41, against 11 of 40 on placebo.¹ After almost seven years, the difference held: 4 of 41 against 16 of 40.²

Larger trials did not confirm it. In NEURAPRO, at 10 sites in Australia, Asia and Europe, 304 young people took omega-3 or a placebo for six months, alongside regular support from a case manager. After a year, about 11 in 100 in each group had developed psychosis.³ After three and a half years, there was still no difference.⁴

The European PURPOSE trial, led from Utrecht, included 135 young people aged 13 to 20 in eight European countries and Israel. Psychosis developed in 5 of 67 on omega-3 and 3 of 68 on placebo; the trial stopped early, mainly because the COVID-19 pandemic slowed recruitment.⁵ Across 24 trials with 3,236 people at high risk, no preventive treatment, omega-3 included, reliably lowered the number who went on to develop psychosis.⁶

Side effects

In the trials, side effects were no more common on omega-3 than on placebo.^1,5

Trials in Europe

The PsyCARE trial in France assigns omega-3 or N-acetylcysteine (opens in a new tab) to people with psychosis according to their biological profile.⁷

What we don’t know yet

• Why the Vienna trial found such a large effect and the larger trials none.
• Whether omega-3 helps a subgroup, for example people with low levels of these fats in their blood.