A recent study by the Keck Center for Medicine at the University of Southern California showed that omega-3 supplements may have little effect in preventing cognitive decline or Alzheimer's disease in older adults.
The study included a two-year, strictly controlled clinical trial using a placebo, focusing on older adults at high risk of developing Alzheimer's disease. The researchers concluded that high doses of omega-3 fatty acids did not improve memory or cognitive function, nor did they reduce brain cell loss in areas associated with the disease.
The study included 365 participants aged between 55 and 80 years, who rarely ate fish, the primary natural source of omega-3 fatty acids, and about 47% of them carried the APOE4 gene, known to be the strongest genetic risk factor for developing late-onset Alzheimer's disease.
The researchers randomly divided the participants into two groups: one group received fish oil supplements daily, while the other received a placebo. The supplement contained 2000 mg of docosahexaenoic acid (DHA), one of the most important omega-3 fatty acids linked to brain function.
The results showed that DHA did indeed reach the brain, with its levels in cerebrospinal fluid increasing by 17% after six months. However, no differences in cognitive abilities were observed between those taking the supplement and those taking the placebo after two years of follow-up, nor did the tests show any slowing of hippocampal shrinkage, a brain region associated with memory and used as an indicator of Alzheimer's disease progression.
"We hope for a simple solution to prevent Alzheimer's, but our results suggest that fish oil supplements don't protect the brain as much as expected," said Dr. Hussein Nagi Yassin, director of the Center for Personalized Brain Health at the University of Southern California and lead researcher on the study. He added that while omega-3 fatty acids remain important for brain function, taking them as supplements doesn't appear sufficient to provide adequate protection.
Researchers are currently working to understand why omega-3 reaches the brain without producing a clear improvement, with the possibility that it is more effective when consumed as part of a Mediterranean diet rich in fish and natural foods, a dietary pattern that has been linked to a reduced risk of Alzheimer's.
Yassin pointed out that a generally healthy lifestyle remains a key factor in protecting the brain, explaining that regular exercise, good sleep, and a balanced diet can reduce the risk of cognitive decline. He said that brain health is like car maintenance; neglecting health aspects leads over time to a decline in functions, just as engines break down without maintenance.
