LOS ANGELES, June 30 — 365 older adults. Two years. Zero measurable brain benefit from fish oil supplements.
That is the bottom line from a new placebo-controlled, double-blinded trial out of Keck Medicine of the University of Southern California. The study followed adults aged 55 to 80 who rarely ate fish and were at elevated risk of developing Alzheimer’s disease.
Researchers found that high doses of omega-3s did not improve memory, cognitive performance, or prevent brain cell loss in regions associated with the disease. “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 Hussein Naji Yassine, MD, director of the USC Center for Personalized Brain Health and lead investigator of the study. Nearly half of participants — 47% — carried the APOE4 gene, the strongest known genetic risk factor for late-onset Alzheimer’s.
Participants were randomly assigned to receive either daily fish oil supplements or a placebo. The supplement contained 2,000 mg of docosahexaenoic acid (DHA), an omega-3 fatty acid linked to brain function.
Researchers first checked whether DHA from the supplement actually reached the brain. By measuring levels in cerebrospinal fluid, they confirmed the nutrients did arrive. Yet that delivery did not translate into cognitive protection.
“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,” Yassine said. The figure that matters for investors and consumers alike: a two-year, rigorous trial showing no effect, despite the nutrients reaching their target. The study recruited adults who rarely ate fish, a natural source of omega-3 fatty acids, and who were considered at increased risk of Alzheimer’s.
For the supplement industry, which has long marketed omega-3s for brain health, the data is sobering. For researchers, the next question is whether different doses, earlier intervention, or specific genetic subgroups might change the outcome.
Yassine’s team at USC plans to continue investigating personalized approaches to brain health. Consult your doctor for medical advice.
