Docosahexaenoic Acid Supplement Does Not Improve Cognitive Performance

MONDAY, July 6, 2026 (HealthDay News) — High-dose docosahexaenoic acid (DHA) supplementation does not yield a change in brain volume or cognitive performance over 24 months, according to a study published online June 18 in eBioMedicine.

Hussein N. Yassine, M.D., from the University of Southern California in Los Angeles, and colleagues conducted a phase 2a 24-month randomized trial involving adults aged 55 to 80 years without dementia with low dietary DHA intake and one or more dementia risk factors. Participants were stratified by cerebrospinal fluid (CSF) collection willingness into lumbar puncture (LP) or no-LP arms (181 and 184 participants, respectively). Participants were randomly assigned within each arm to receive 2 g/day DHA or placebo, with stratification by APOE ε4 status.

The researchers found that at six months, DHA supplementation increased CSF DHA-to-arachidonic acid ratio compared with placebo (0.17 versus −0.02), independent of APOE ε4 status. Thirty-eight percent of participants dropped out, mainly due to COVID-19. Over 24 months, no treatment differences were seen in brain volume or cognitive performance. The groups had comparable adverse events, with no serious adverse events due to treatment.

“We all wish there was a silver bullet for preventing Alzheimer [disease], but our findings showed that fish oil supplements do not appear to protect brain health,” Yassine said in a statement. “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.”

One author disclosed ties to the biopharmaceutical industry.

Abstract/Full Text