DHA Reaches the Brain but Brings No Edge in Thinking Tests
Graded Moderate — a random draw assigned 365 people to DHA or a dummy pill for two years; a single study site and a 38 percent dropout rate weaken the findings on thinking.
- Design
- Randomized controlled trial
- Participants
- 365
- Duration
- 2 years
- Funding
- National Institute on Aging (NIH); Alzheimer's Drug Discovery Foundation (ADDF)
Two grams of DHA a day reached the spinal fluid but brought no measurable gain on thinking tests over two years.
A daily two grams of the omega-3 fat DHA does reach the nervous system. Researchers saw it in spinal fluid, the liquid that surrounds the brain and spinal cord. After six months, the ratio of DHA to another fatty acid there had risen. Yet after two years, people scored no better on thinking tests than those on a dummy pill. Brain volume showed no clear difference either.
The trial ran at the University of Southern California with 365 people aged 55 to 80. None had dementia. All ate little DHA and had at least one dementia risk factor. They were chosen at random to take DHA capsules or look-alike capsules of corn and soybean oil. Almost half carried APOE ε4, a gene variant that raises Alzheimer's risk. In them, DHA reached the spinal fluid just as well.
The trial has limits. Some 38 percent dropped out, mostly because of COVID-19. Participants were also fairly young, well educated and mentally sharp, which may hide small effects. The authors conclude that research should now focus on how the brain handles DHA rather than on more supplement trials.
Conflict of Interest Disclosure: One author reports grants and consulting fees from drug companies such as Biogen, Eisai and Eli Lilly, outside this study.
Disclaimer: Research summaries are provided for informational purposes only and do not constitute medical advice. Always consult a qualified healthcare professional before making changes to your health routine.