Close adherence to the Mediterenean diet is tied to higher cognitive function, and may play a role in slowing cognitive decline, according to a National Institutes of Health-funded study.

Among more than 7,700 participants, those who stuck closely to the diet had the lowest likelihood of cognitive impairment. In addition, some food categories had a greater effect than others. 

The Mediterrenean diet is heavy in whole fruits, vegetables, whole grains, nuts, legumes, fish, and olive oil, and contains little red meat and alcohol. In the study, high fish and vegetable consumption was found to have the greatest protective effect. At 10 years, participants who consumed the most fish had a significantly slower cognitive decline rate, reported Emily Y. Chew, M.D., from the National Eye Institute, and colleagues.

The diet had the same effect whether or not participants had a gene predisposing them to Alzheimer’s disease, said the investigators. The takeaway is that diet can play a role in reducing dementia risk even in those who are more susceptible.

The diet’s overall effects were too small for individuals to notice, the researchers noted. But on a population level the effects are clear, they concluded. 

The study, part of a larger project looking at eye health, was published in Alzheimer’s & Dementia.