High-dose DHA (fish oil) supplements don't protect brain health or boost cognition, according to a new phase 2a randomized trial. Over 24 months, adults at risk for dementia who took 2g/day of DHA showed no difference in brain volume or cognitive performance compared to placebo. Researchers say fish oil is no silver bullet for Alzheimer's prevention.
Hope for a simple Alzheimer's prevention strategy takes a hit. A phase 2a randomized trial published in eBioMedicine found that high-dose docosahexaenoic acid (DHA) — the omega-3 fatty acid found in fish oil — did not improve brain volume or cognitive performance over 24 months. The study enrolled adults aged 55–80 with low dietary DHA intake and at least one dementia risk factor, randomizing them to 2g/day of DHA or placebo.
There was one early bright spot: at six months, DHA supplementation did raise cerebrospinal fluid DHA levels compared to placebo, suggesting the supplement does reach the brain. But that biological signal didn't translate into any measurable cognitive or structural brain benefit by the two-year mark.
Key Takeaways:
Why it matters: With millions of people taking fish oil supplements hoping to stave off cognitive decline, this trial delivers a clear message: omega-3 supplements are not a proven preventive strategy for Alzheimer's disease.
