Key Takeaway:
- Fish oil supplements did not improve memory or reduce Alzheimer’s risk in adults at elevated risk, despite increasing DHA levels in the brain.
- Researchers found no difference in cognitive performance or brain shrinkage between participants taking DHA supplements and those receiving a placebo.
- Healthy lifestyle habits and a Mediterranean-style diet remain the most evidence-based approaches for supporting long-term brain health.
A new study from the University of Southern California has found that fish oil supplements do not improve memory, cognitive function or brain health in adults at increased risk of Alzheimer’s disease, despite raising omega-3 levels in the brain.
Researchers Find No Cognitive Benefit From Supplements
Researchers at the Keck School of Medicine reported that fish oil supplements containing high doses of omega-3 fatty acids failed to slow cognitive decline or protect brain health in adults at elevated risk of Alzheimer’s disease.
The double-blind, placebo-controlled study followed 365 adults aged 55 to 80 over two years. Participants were randomly assigned to receive either a daily placebo or a supplement containing 2,000 milligrams of docosahexaenoic acid, or DHA, an omega-3 fatty acid linked to brain function.
“We all wish there was a silver bullet for preventing Alzheimer’s, but our findings showed that fish oil supplements do not appear to protect brain health,” said Dr. Hussein Naji Yassine, director of the USC Center for Personalized Brain Health and the study’s lead investigator.
Yassine said omega-3 fatty acids remain important for normal brain function, but the results do not support fish oil supplements as a preventive measure against Alzheimer’s disease.
DHA Reaches The Brain But Shows No Lasting Effect
Researchers first examined whether DHA from fish oil supplements reached the brain. After six months, participants taking the supplement showed a 17% increase in DHA levels in the cerebrospinal fluid surrounding the brain and spinal cord.
Despite that increase, cognitive testing found no meaningful difference between participants taking DHA and those receiving the placebo after two years. Memory and thinking abilities declined at similar rates in both groups.
Brain imaging produced similar findings. Researchers observed that the hippocampus, a brain region critical for memory and commonly monitored in Alzheimer’s research, shrank at comparable rates regardless of whether participants received the supplement or placebo.
The findings suggest that simply increasing DHA levels in the brain through fish oil supplements does not translate into measurable improvements in cognition or protection against brain aging associated with Alzheimer’s disease.
Researchers Shift Focus To Brain Health And Lifestyle
The research team said future studies will explore why the brain does not appear to use the additional DHA effectively. Investigators plan to examine whether factors such as age, genetics, overall health, and dietary patterns influence how the brain processes omega-3 fatty acids.
“We’re focused on better understanding how the brain processes omega-3s and whether factors, such as poor health, dietary pattern, genetic risk and age, may change the brain’s ability to effectively absorb and use omega-3s,” Yassine said. “We are working to develop medications that may help the brain better utilize these nutrients to preserve cognitive function.”
Researchers emphasized that the findings do not diminish the value of omega-3 fatty acids obtained through food. They said a Mediterranean-style diet, which includes fish and other nutrient-rich foods, remains one of the strongest dietary approaches for reducing Alzheimer’s risk.
The team also pointed to regular exercise, adequate sleep, and a balanced diet as the most effective strategies currently supported by evidence for maintaining long-term brain health and lowering the risk of cognitive decline.
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