• Robert Preidt
• Posted December 22, 2021

Fish Oil Has No Effect on Depression, Study Finds

They may have other proven health benefits, but new research shows that fish oil supplements don't prevent depression or improve mood.

Some experts recommend omega-3 fish oil supplements to help prevent depression in high-risk patients, but studies have yielded mixed results and there are no guidelines on using fish oil for that purpose in the general population.

To learn more, researchers studied over 18,000 depression-free adults, 50 and older, who took vitamin D and/or omega-3 supplements or placebos for between 5 and 7 years, on average.

The investigators found no evidence that omega-3 supplements warded off depression or boosted mood, according to the report published Dec. 21 in the Journal of the American Medical Association.

"There are still health reasons for some people, under the guidance of their health care providers, to take omega-3 fish oil supplements," said senior author Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital and a professor of medicine at Harvard Medical School, in Boston.

Manson noted that these supplements have increasingly been found to have benefits for heart health and treatment of inflammatory conditions, in addition to being used to manage existing depressive disorders in high-risk patients.

"However," she added, "our findings indicate there is no reason for adults without depression in the general population to take fish oil supplements solely for the purpose of preventing depression or for maintaining a positive mood."

The study was the largest clinical trial of its kind and represents a "significant step," according to lead author Dr. Olivia Okereke. She is director of geriatric psychiatry at Massachusetts General Hospital (MGH) and an associate professor of psychiatry at Harvard Medical School.

"It requires many thousands of people to conduct this type of study of preventing depression in adults -- something we call universal prevention -- and the participants were taking randomized study pills for between 5 to 7 years on average," Okereke pointed out in an MGH news release. "So, it is rare to see a long-term randomized trial of this kind."

More information

The U.S. National Institute of Mental Health has more on depression.

SOURCE: Massachusetts General Hospital, news release, Dec. 21, 2021