No mental health benefit from fish oil

In spite of conventional wisdom that the omega-3 fatty acids found in fish can protect against depression, a large new study from Harvard School of Public Health (HSPH) found no such benefit.

Researchers examined the link between suicide and fatty acid intake among more than 205,000 participants in three long-term studies. Looking at data from biennial questionnaires administered to 42,290 men enrolled in the Health Professionals Follow-up Study (1988-2008), 72, 231 women in the Nurses’ Health Study (1986-2008), and 90,836 women in the Nurses’ Health Study II (1993-2007), they found no evidence that intake of fatty acids or fish lowered the risk of suicide.

“From a public health perspective, this is highly significant,” said Alexander Tsai, assistant professor of psychiatry at Harvard Medical School and the Massachusetts General Hospital and a research fellow at the Harvard Center for Population and Development Studies, who co-led the study with Michel Lucas, visiting scientist in the HSPH Department of Nutrition. “The vast majority of previous literature on whether there is a mental health benefit from fatty acid intake has been based on depression screening data. Our study represents one of the few times—and it is certainly the largest of its kind—that this relationship has been studied with hard data on suicide mortality.”

The study was published May 8, 2014 in the American Journal of Epidemiology. Other HSPH authors included senior author Walter Willett, chair of the HSPH Department of Nutrition; Olivia Okereke, assistant professor in the Department of Epidemiology; Eilis O’Reilly, research associate in the Department of Nutrition; Fariba Mirzaei, research fellow in the Neuroepidemiology Research Group; Ichiro Kawachi, professor of social epidemiology and chair of the Department of Social and Behavioral Sciences; and Alberto Ascherio, professor of epidemiology and nutrition.

Study abstract: Suicide Mortality in Relation to Dietary Intake of n-3 and n-6 Polyunsaturated Fatty Acids and Fish: Equivocal Findings From 3 Large US Cohort Studies

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Ask the Expert: Omega-3 Fatty Acids (HSPH Nutrition Source)