Fish oil for brain health: Are omega-3 supplements actually good?

Omega-3 fatty acid supplements, like fish oil, are theoretically beneficial for brain health, as these acids are essential for building brain cells and facilitating communication between neurons. Studies have indicated that individuals with higher omega-3 levels exhibit better cognitive function and healthier brain structures, along with a reduced risk of dementia. Conversely, those with Alzheimer's disease often show lower omega-3 levels.

However, a significant disconnect exists between these observations and the results of clinical trials. The vast majority of these trials have failed to demonstrate any substantial benefit from omega-3 supplements for cognition or dementia symptoms. Dr. Kristine Yaffe, a professor at the University of California, San Francisco, noted that while it intuitively makes sense for neurons to require fatty acids, the trial evidence largely does not support supplementation.

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It kind of intuitively makes sense” that neurons need fatty acids for their health, so you should take a fatty acid supplement. The problem is that most of the evidence, particularly the trial evidence, just doesn’t support it at all.

A recent clinical trial exemplified this issue. It involved older adults with low fish intake and increased genetic risk for Alzheimer's, groups expected to benefit most. Researchers even confirmed the supplement increased omega-3 levels in the brain. Yet, compared to a placebo, no cognitive or structural brain benefits were observed.

Scientists propose several hypotheses for this discrepancy, primarily linked to diet and lifestyle. One key theory suggests that most people already consume sufficient omega-3s. The body needs EPA and DHA (found in fish) and can convert ALA (from nuts and seeds) into these. Richard Bazinet, a professor at the University of Toronto, believes that dietary ALA intake is high enough for the liver to convert it into the small amount of DHA the brain uses daily, meaning supplementation is often redundant.

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We all eat a ton of” ALA. And if people’s DHA intake is low, the liver can convert the ALA to DHA and send it to the brain.