Fish oil supplements may not reduce risk of Alzheimer’s disease, study finds

A clinical trial found that taking high-dose omega-3 supplements for 2 years did not improve memory or thinking skills in older adults at increased risk of Alzheimer’s disease.

Keck Medicine of USC researchers led the study, published in eBioMedicine. Participants took either a high-dose daily supplement of docosahexaenoic acid (DHA), an omega-3 fatty acid, or a placebo.

Fish oil is one of the best-known ways to get omega-3. However, the supplement in this clinical trial was not made from fish, Hussein Yassine, MD, director of the USC Center for Personalized Brain Health with Keck Medicine of USC and principal investigator of the study, told Healthline. This article uses the broader term omega-3 supplements.

The researchers found that taking the supplements increased omega-3 levels in the participants’ brains, but it did not change their memory, thinking skills, or brain structure.

Dung Trinh, MD, an internist at MemorialCare Medical Group and chief medical officer of the Healthy Brain Clinic in Irvine, California, who was not involved in the study, told Healthline that the findings challenge the common belief that omega-3 supplements, such as fish oil, can help prevent Alzheimer’s disease or improve memory.

Millions of older adults take omega-3 supplements. In a 2017-2018 federal survey, 21.8% of U.S. adults ages 60 and older reported taking an omega-3 fatty acid supplement in the past 30 days, according to the Centers for Disease Control and Prevention (CDC).