A new study suggests that swallowing fish pills and snacking on nuts won’t prevent cognitive decline.

Omega-3s fatty acids, found in foods like salmon, walnuts and leafy greens as well as fish oil and other supplements, are associated with health benefits including reduced risk of stroke and heart disease. The fatty acids are needed for blood clotting, building cell membranes in the brain and other essential functions.

Previous studies also indicated a possible connection between omega-3s and memory. Researchers suggested that they may improve vascular function and boost memory in those with high levels of the fatty acids in their blood.

“There has been a lot of interest in omega-3s as a way to prevent or delay cognitive decline, but unfortunately our study did not find a protective effect in older women,” said study author Eric Ammann, a Ph.D. student at the University of Iowa.

The study, published online today in advance of print in the journal Neurology, evaluated the medical records of about 2,100 women aged 65-80. The women in the study were enrolled in the Women’s Health Initiative Study of Cognitive Aging and took cognitive function tests for six years on average. Participants also gave blood samples at the start of the study, which researchers used to establish levels of omega-3s.

When women with higher levels of omega-3s were compared to women with lower levels, there was no significant difference between the two groups on the tests. Women with both high and low levels of the fatty acids performed comparably in their cognitive function, including memory function, over the course of the study.

Omega-3s did not appear to slow cognitive decline, but people shouldn’t stop eating fatty fish and leafy greens, Ammann said.

“Researchers continue to study the relationship between omega-3s and the health of the heart, blood vessels and brain.” Ammann said. “We know that fish and nuts can be healthy alternatives to red meat and full-fat dairy products.”