People who followed the diet closely over three years experienced less age-related brain shrinkage than those who did not, scientists found.
The Mediterranean diet is rich in vegetables, fruits, olive oil, beans and cereal grains and includes moderate amounts of fish, dairy products and wine while limiting consumption of red meat and poultry.
Scientists carried out brain scans on 401 people in their 70s who provided information about what they ate.
Those who adhered most closely to a Mediterranean diet retained significantly greater brain volume after three years than those with different eating habits.
Diet accounted for about half the variation in brain volume seen across all the study participants. Lead researcher Dr Michelle Luciano, from the University of Edinburgh, said: “As we age, the brain shrinks and we lose brain cells, which can affect learning and memory.
“This study adds to the body of evidence that suggests the Mediterranean diet has a positive impact on brain health.”
Eating more fish and less meat was not associated with differences between people’s brains, contrary to earlier findings.