Millions take but a new study found no benefit
Americans spend more than $1 billion each year on fish oil supplements, largely because of claims that the omega-3 fatty acids they contain can support brain health. These essential nutrients help build and maintain the connections between brain cells that are important for thinking and memory.
But new research from Keck Medicine of USC suggests that boosting omega-3 levels through supplements may not provide the brain benefits many people expect. The study, published in eBioMedicine, found that although omega-3s from fish oil successfully reached the brain, they did not improve measures of brain health in older adults at increased risk of Alzheimer’s disease.
Over the course of a two-year, placebo-controlled, double-blinded clinical trial, researchers found that high-dose omega-3 supplements failed to improve memory, cognitive performance or brain cell loss in regions associated with Alzheimer’s.
“We all wish there was a silver bullet for preventing Alzheimer’s, but our findings showed that fish oil supplements do not appear to protect brain health,” said physician Hussein Naji Yassine, director of the USC Center for Personalized Brain Health and lead investigator of the study. “While omega-3s play an important role in forming brain cell connections needed for cognition, our results do not support fish oil supplements as a preventive measure against Alzheimer’s.”
The study included 365 adults between the ages of 55 and 80 who rarely consumed fish, a major dietary source of omega-3 fatty acids. Researchers considered all participants to be at elevated risk for Alzheimer’s disease. Nearly half (47%) carried the APOE4 gene, the strongest known genetic risk factor for late-onset Alzheimer’s.
Participants were randomly assigned to receive either a daily fish oil supplement or a placebo. Each supplement contained 2,000 mg of docosahexaenoic acid (DHA), an omega-3 fatty acid that plays an important role in brain function.
One of the researchers’ first goals was to determine whether DHA from the supplements could actually make its way into the brain.
To answer that question, they measured DHA levels in cerebrospinal fluid, which surrounds the brain and spinal cord. After six months, DHA levels had increased by an average of 17%, confirming that the nutrient had successfully reached its intended destination.
The findings have prompted researchers to investigate why omega-3s can reach the brain without producing noticeable improvements in brain health.
Based on earlier research, Yassine and his colleagues suspect that omega-3s may be more effective when consumed as part of an overall Mediterranean-style eating pattern rather than as a standalone supplement. The Mediterranean diet is naturally rich in omega-3s and has been associated with a lower risk of Alzheimer’s disease.
“We’re focused on better understanding how the brain processes omega-3s and whether factors, such as poor health, dietary pattern, genetic risk and age, may change the brain’s ability to effectively absorb and use omega-3s,” said Yassine. “We are working to develop medications that may help the brain better utilize these nutrients to preserve cognitive function.”