A three-month course of the supplement appeared to be as effective as drugs, cutting the rate of psychotic illness like schizophrenia by a quarter. The researchers believe that it is the omega-3 fats found in fish oil that has beneficial effects in the brain.

"The finding that treatment with a natural substance may prevent, or at least delay, the onset of psychotic disorder gives hope that there may be alternatives to antipsychotic drugs," the study authors said.

Antipsychotic drugs are can have serious side effects, but fish oil supplements, on the other hand, are generally well tolerated and easy to take, say the scientists.

Study Details

Scientists tested the treatment in 81 people deemed to be at particularly high risk of developing psychosis. This was down to a strong family history of schizophrenia, or similar disorders, or them already showing mild symptoms of these conditions themselves.

For the test, half of the individuals took fish oil supplements (1.2 grams of omega-3 fatty acids) for 12 weeks, while the other half took only a dummy pill. Neither group knew which treatment they were receiving.

The team followed the groups for a year to see how many, if any, went on to develop illness.

Two in the fish oil group developed a psychotic disorder compared to 11 in the placebo group.

Based on the results, the investigators estimate that one high-risk adult could be protected from developing psychosis for every four treated over a year.

They believe the omega-3 fatty acids found in the supplements may alter brain signaling in the brain with beneficial effects.

Polyunsaturated fatty acids also significantly reduced symptoms and improved functioning compared with placebo, and adverse effects were minimal.

Omega-3 fats such as those found in fish oils have other important health benefits too. As well as brain health, they are necessary for overall health, including strengthening the immune system, protecting heart health and preventing against cancer.

Research Paper Details

Amminger GP, Schafer MR, Papageorgiou K, et al. Long-Chain omega-3 fatty acids for Indicated Prevention of Psychotic Disorders: A Randomized, Placebo-Controlled Trial. Arch Gen Psychiatry, 2010; 67 (2): 146-154.