What to Eat to for Better Memory: A Mostly Plant-Based Diet, Says a Study

Eating a diet that's high in vegetables, whole grains and high-fiber foods, with a small amount of fish but minimal meat and dairy could be the answer to how to reduce your longterm risk of developing dementia, two new studies from the U.S. National Eye Institute (NEI) suggest.

"We need to explore how nutrition affects the brain and the eye," lead author Dr. Emily Chew said in an NEI news release. She is the director of the institute's division of epidemiology and clinical applications. The findings were a surprising outcome of a broad-based study designed to research aging and eye health.

The researchers analyzed data from the Age-Related Eye Disease Study (AREDS1) and its follow-up study  Age-Related Eye Disease Study 2, (AREDS2) which together included 8,000 people. Those were designed to explore age-related eye disease, macular degeneration. What they found has far-reaching implications for dementia and the connection to diet.

Participants' diets were assessed, before and during the course of the study, including their average consumption of specific Mediterranean diet components over the previous year. Besides vegetables, whole grains and fish, this type of meal plan is rich in whole fruits, nuts, legumes, and olive oil and is lower in the consumption of red meat and alcohol.

The study tested participants' mental, cognitive function at five years, and the follow-up study tested cognitive function at the start of that study and again two, four and 10 years later. Over the course of 15 years, those participants who most closely followed the Mediterranean diet had the lowest risk of mental impairment.

The highest levels of fish and vegetable consumption appeared to provide the greatest protection. And although cause and effect is not provable in this kind of research, at 10 years, those in the second study who ate the most fish had the slowest rate of mental decline. The findings were published April 14 in the journal Alzheimer's and Dementia.

The researchers also found that people with the APOE gene,  which puts them at higher risk for Alzheimer's disease, on average had lower cognitive function scores and greater mental decline than those without the gene. The benefits of closely following a Mediterranean diet were similar for people with and without the APOE gene. This means the effects of diet on mental function are independent of genetic risk for Alzheimer's disease, according to the researchers.