Researchers tried maxing out omega-3s for brain health—here’s what happened.

Reviewed by Dietitian Emily Lachtrupp, M.S., RD

Key Points

  • Docosahexaenoic acid (DHA), an omega-3 fatty acid, is often supplemented for brain health.
  • Researchers provided high-dose DHA supplements to adults at risk for Alzheimer’s disease.
  • DHA levels in the brain increased, but no changes in cognitive function occurred.

If you’ve spent any time on social media lately, you’ve likely come across the “maxxing” trend—a viral phenomenon centered around optimizing everyday habits. As a dietitian, I’m most familiar with “fibermaxxing,” or dramatically increasing fiber intake to support gut health. But nutrition maxxing doesn’t stop there.

In fact, researchers have been exploring the idea of pushing certain nutrients beyond typical intake levels for some time in order to better understand whether higher doses may influence micronutrient deficiencies and long-term health outcomes. However they’re not doing this using everyday supplements—in some cases, researchers test doses far beyond what you’d typically find over the counter.

Recently, researchers applied this idea to docosahexaenoic acid (DHA), an omega-3 fatty acid and key structural component of brain cell membranes. DHA plays an important role in brain health throughout life, but researchers have been especially interested in whether higher doses of it may benefit people at higher risk of developing Alzheimer’s disease–including those who carry genetic variants associated with differences in how the brain processes and uses DHA.

Related video: Creatine linked to cognitive boost in Alzheimer's patients (PsyPost)In this 24-month randomized controlled trial, researchers recruited 365 relatively healthy adults—with no cognitive impairments—between the ages of 55 and 80. Participants had relatively low dietary DHA intake (less than 200 milligrams per day) and at least one cardiovascular or dementia-related risk factor. Once the sample size was established, researchers tested participants for the apolipoprotein E4 gene variant—the strongest known genetic risk factor for Alzheimer’s disease—because one of the study’s goals was to understand whether possessing this gene influenced the response to DHA supplementation and DHA metabolism. Next, participants were randomly assigned to receive either high-dose DHA supplementation (2 grams per day) or a placebo for 24 months. Throughout the study, researchers measured whether DHA levels increased in the cerebrospinal fluid—the fluid surrounding the brain—to determine whether the supplement was actually reaching the central nervous system. Researchers assessed these levels after six months. They also evaluated changes in cognitive performance and markers of brain structure and health over the two year period.What Did the Study Find?Researchers found that high-dose DHA supplementation of 2 grams per day significantly increased DHA levels in the cerebrospinal fluid after six months, regardless of whether or not participants carried the APOE ε4 gene variant. This finding is notable because it confirms that increasing DHA delivery to the brain through supplementation is possible in adults with low dietary DHA intake. But while the high-dose supplementation successfully increased DHA levels in the brain, researchers did not observe improvements in cognitive performance or markers of brain structure over the 24-month study period. This finding was true for both APOE ε4 carriers as well as noncarriers. When considered overall, these findings suggest that simply increasing DHA levels in the brain may not be enough to preserve cognition in relatively healthy adults at higher risk for Alzheimer’s disease. That said, the study helps answer an important question that has remained unanswered from previous omega-3 research: Higher doses of DHA can reach the brain—they just may not be sufficient on their own in influencing cognitive outcomes.