Fish oil may counter schizophrenia

Taking fish oil capsules for just three months can stave off psychosis for years, a small study suggests. If confirmed in larger studies, the results suggest that the common dietary supplement may actually prevent schizophrenia.

Such enduring benefits would be extraordinary, if correct, says psychiatrist Jeffrey Lieberman of Columbia University Medical Center in New York City. “I don’t want to sound like a cynic or a skeptic, but it’s almost too good to be true.” Larger studies must confirm the results, he says. “I still want to see replication before I’m ready to say we have a new standard of care.”

In 2010, Paul Amminger of the University of Melbourne in Australia and colleagues reported a tantalizing result with fish oil: For a small group of young people at high risk of developing schizophrenia, three months of taking 1.2 grams a day of anti-inflammatory omega-3 fatty acids reduced the risk of psychotic disorders for a year. The researchers’ new study, published online August 11 in Nature Communications, suggests that for many of those people, protection lasts for nearly seven years.

On average, the participants were 16 years old when the study began. During the nearly seven-year follow-up, four of 41 participants who took fish oil developed psychosis, marked by more than a week of hallucinations, delusions and altered thinking. Over the same time period, 16 of the 40 participants who received a placebo became psychotic.

Schizophrenia often emerges in early adulthood — suggesting that treatments might be particularly effective just before that window. “The timing of the intervention is probably very important for its effect,” says Amminger, though studies on older people are needed. It’s not clear how the fish oil works, but Amminger thinks that the benefits may come from the omega-3s’ inflammation-fighting properties. Some studies have tied schizophrenia to inflammation, and scientists are testing whether other anti-inflammatory treatments might curb psychosis. 

Amminger and colleagues are now conducting a larger, international study of 304 people, and early results are mixed. After a year, there were no differences in the incidence of psychosis between people who took fish oil and those who took a placebo, though Amminger says that compliance may be to blame for those preliminary negative results. When the researchers factored in who had actually taken the drug, the results were positive, he says. A different clinical trial based in the United States and Canada is looking at omega-3s’ effect on psychosis on 127 young people, with results expected in 2016.

The promise of fish oil is huge, but tenuous, says psychiatrist William Carpenter of the University of Maryland School of Medicine in Baltimore. “This, if it works out, will probably be the most important advance that we’ve made in many, many decades,” he says. But seemingly promising advances in mental health have a history of disappointment, he adds. “In our field, we don’t really have much luck.”