Omega-3 fatty acids may not help keep the aging brain sharp, at least in older women, new research suggests.
The study, published today (Sept. 25) in the journal Neurology, found that there were no differences in the cognitive skills of older women who had high blood levels of the fatty acids compared with those whose levels were lower.
"Our study of omega-3 blood levels and cognitive function did not find a protective association in older, postmenopausal women," study co-author Eric Ammann, a doctoral researcher in epidemiology at the University of Iowa, wrote in an email to LiveScience.
Along with randomized trials also showing no effect, the findings suggest that omega-3s may not be the brain booster they were once thought to be, Ammann said.
Early studies found that people who consumed more fish and nuts tended to have sharper minds and better memories than those who didn't. And other studies found that omega-3 fatty acids reduce inflammation, which is a risk factor for heart disease.
But a recent randomized trial found that people taking omega-3 supplements did not have a lower risk for cognitive decline or improvements in memory. [6 Foods That Are Good for Your Brain]
Ammann and his colleagues measured the blood levels of omega-3s in 2,157 women ages 65 and older. The women completed a series of cognitive tests over five years, aimed at measuring their working memory, verbal skills and spatial ability.
The team found no differences over the course of the study in the cognitive function or decline of older women with high versus low levels of the fatty acid. That suggests the omega-3s were not providing a brain boost for the women, the researchers said.
While past studies suggested that people who eat more omega-3 rich foods do tend to have better brain function, "this might not be cause-and-effect," Ammann said.
"People who eat lots of fish or nuts, or who take omega-3 supplements, tend to be more affluent and health-conscious than those who don't," he said. Women in the study with higher levels of blood omega-3s also tended to eat more fish.
"They are also less likely to smoke, more likely to exercise, and have a lower body mass index," all factors that are separately tied to better brain health and health overall, Ammann said.