Americans invest over $1 billion annually in fish oil supplements, primarily due to claims that the omega-3 fatty acids they contain can enhance brain health. These nutrients are essential for forming and maintaining connections between brain cells, which are crucial for cognitive functions like thinking and memory.
However, new findings from Keck Medicine at USC indicate that increasing omega-3 levels through supplements may not deliver the brain benefits many hope for. A study published in eBioMedicine revealed that while omega-3s from fish oil did reach the brain, they didn’t enhance measures of brain health in older adults who are at higher risk for Alzheimer’s disease.
During a two-year, placebo-controlled clinical trial, researchers discovered that high doses of omega-3 supplements did not lead to improvements in memory, cognitive performance, or the loss of brain cells in regions associated with Alzheimer’s.
“It’s a common hope that there would be a straightforward solution for preventing Alzheimer’s, yet our results suggest that fish oil supplements do not seem to safeguard brain health,” noted Hussein Naji Yassine, MD, who leads the USC Center for Personalized Brain Health and the study. “While omega-3s are critical for forming brain cell connections essential for cognition, our findings do not back the use of fish oil supplements as a preventive measure against Alzheimer’s.”
Fish Oil Reached the Brain
The study involved 365 adults aged 55 to 80 who rarely ate fish, a primary source of omega-3 fatty acids. All participants were deemed to have an increased risk of Alzheimer’s, with nearly half (47%) carrying the APOE4 gene, known to elevate the risk of late-onset Alzheimer’s.
Participants were randomly assigned to daily doses of either a fish oil supplement or a placebo. Each supplement contained 2,000 mg of docosahexaenoic acid (DHA), an omega-3 fatty acid vital for brain function.
The research initially aimed to ascertain whether DHA from the supplements could actually reach the brain.
To investigate this, DHA levels were measured in the cerebrospinal fluid that encases the brain and spinal cord. After six months, DHA levels had risen by an average of 17%, confirming successful absorption into the brain.
No Improvement in Memory or Brain Aging
Even though DHA made it to the brain, it didn’t result in noticeable cognitive benefits.
Assessments of memory and cognitive abilities were performed at the beginning of the study and two years later. Those taking DHA supplements showed no improvement in cognitive tests compared to those who received the placebo.
Brain imaging results echoed these findings. The scans indicated that fish oil supplements did not slow down the shrinkage of the hippocampus, a crucial brain area for memory that also serves as a marker for brain aging and Alzheimer’s risk.
Why Didn’t Omega-3s Help?
This research has sparked an investigation into why omega-3s can enter the brain but fail to demonstrate clear benefits for brain health.
Drawing on previous research, Yassine and his team speculate that omega-3s might be more effective when consumed within a broader Mediterranean-style diet, rather than as isolated supplements. This diet is naturally high in omega-3s and is linked to a lower risk of Alzheimer’s disease.
“We aim to gain a better understanding of how the brain processes omega-3s and whether factors like overall health, diet, genetic predisposition, and age might influence the brain’s capacity to absorb and utilize omega-3s,” Yassine explained. “We’re also working on developing treatments that could enhance the brain’s ability to use these nutrients to maintain cognitive function.”
Healthy Living Still Matters Most
While the study didn’t directly examine lifestyle factors, the researchers stress that maintaining overall health is still one of the best ways to support brain function and lower the risk of Alzheimer’s.
“Staying healthy throughout life is our most effective strategy for reducing Alzheimer’s risk, including regular physical activity, restorative sleep, and a nutritious diet,” Yassine remarked. “Living a healthy lifestyle is akin to regularly taking care of a car; if you neglect maintenance, the engine can fail. In the same way, the brain is more prone to deterioration if health issues elsewhere in the body are not addressed.”
