Eating walnuts may help slow cognitive decline in at-risk groups of the elderly population, according to a study conducted by researchers in California and Spain.

The Walnuts and Healthy Aging Study, published this month in The American Journal of Clinical Nutrition, found that walnut consumption by healthy, elderly adults had little effect on cognitive function over two years, but it had greater effect on elderly adults who had smoked more and had a lower baseline neuropsychological test scores.

The study examined nearly 640 free-living elders in Loma Linda, California, USA, and in Barcelona, Catalonia, Spain. For two years, the test group included walnuts in their daily diet, and the control group abstained from walnuts.

Walnuts contain omega-3 fatty acids and polyphenols, which have previously been found to counteract oxidative stress and inflammation, both of which are drivers of cognitive decline.

Joan Sabaté, MD, DrPH, professor of nutrition and epidemiology at Loma Linda University School of Public Health and the study’s principal investigator, said this was the largest and most well-controlled trial ever conducted on the effects of nuts on cognition.

“While this was a minor result, it could lead to better outcomes when conducted over longer periods of time,” Sabaté said. “Further investigation is definitely warranted based on our findings, especially for disadvantaged populations, who may have the most to gain from incorporating walnuts and other nuts into their diet.”

Sabaté and his research team at Loma Linda University were the first to discover the cholesterol-lowering effect of nut consumption — specifically walnuts — with lowering blood cholesterol. Findings were first published in the New England Journal of Medicine in 1993. Subsequently, findings from Loma Linda University researchers have linked nut consumption to lower risk of cardiovascular diseases.

The Walnuts and Healthy Aging Study was funded by a grant from the California Walnut Commission, which had no input in the study design, data collection, analyses, or writing and submission of the manuscript.