Mediterranean Diet Seen to Protect Aging Brains, But for Reasons That Baffle

A Mediterranean diet may protect against the loss of brain volume associated with aging, researchers report. But eating more fish and less meat was not seen to be related to such beneficial changes, which suggests that other components of the Mediterranean diet — or the sum of all its parts — may be what works to protect the aging brain.

The study, “Mediterranean-Type Diet And Brain Structural Change From 73 To 76 Years In A Scottish Cohort” and published in the journal Neurology, was conducted by researchers at the University of Edinburgh, Scotland.

“As we age, the brain shrinks and we lose brain cells which can affect learning and memory,” Michelle Luciano, PhD, and the study’s first author, said in a news release. “This study adds to the body of evidence that suggests the Mediterranean diet has a positive impact on brain health.”

People who follow a Mediterranean diet usually eat large amounts of fruits and vegetables, olive oil, beans and cereal grains (wheat and rice, for example), as well as moderate amounts of fish, dairy products and wine, but low quantities of red meat and poultry.

Researchers asked 967 people, all around 70 years of age with no symptoms of dementia, to complete a questionnaire on their eating habits and diet. Of this group, 562 underwent an MRI scan over the next three years to assess overall brain volume, gray matter volume, and thickness of the cortex (the outer layer of the brain).

Three years later, 401 people in the group, now 76 years old, underwent a new MRI brain scan. Scan results were then compared between people who had followed the Mediterranean diet for the past three years and those who had not.

Analysis indicated that people not adhering to the Mediterranean diet had a greater increase in brain shrinkage/atrophy than who had followed the diet more closely. Importantly, the effect of diet on brain volume variation was half  that induced by normal aging — and these results were not affected differences in education, diabetes, or high blood pressure, all factors thought to affect brain changes.

Changes in gray matter volume or cortex thickness, however, were not influenced by the Mediterranean diet, the researchers said. Eating more fish and less meat also did not influence brain atrophy, contrary to what has been reported in previous studies. This suggests that other components of the Mediterranean diet, or perhaps the combination of all of its components, may be responsible for a beneficial effect on the brain.

“Lower adherence to the MeDi [Mediterranean diet] in an older Scottish cohort is predictive of total brain atrophy over a 3-year interval,” the researchers wrote. But “[f]ish and meat consumption does not drive this change.”

“In our study, eating habits were measured before brain volume was, which suggests that the diet may be able to provide long-term protection to the brain,” Luciano said in the release. “Still, larger studies are needed to confirm these results.”