Despite hopes that a Mediterranean-style diet would be as good for the head as it is for the heart, a new study among French men and women found little benefit to aging brains.
The research, published in the American Journal of Clinical Nutrition, looked at the participants' dietary patterns in middle age and measured their cognitive performance at around age 65, but found no connection between Mediterranean eating and mental performance.
"They did as careful of a job as possible to find something, but they didn't find anything," said Teresa Fung, a professor of nutrition at Simmons College in Boston who was not involved in the study.
But, Fung said, the results don't definitively answer the question of whether a Mediterranean diet — rich in fruit, vegetables, whole grains, nuts, wine and olive oil — is linked to better brain health.
It's been suggested that the "good" fats in the Mediterranean diet might benefit the brain directly, or that low saturated fats and high fiber in the diet could help stave off cognitive decline indirectly by keeping blood vessels healthy.
And previous research has seemed to uphold that promise. One large study in the Midwest, for example, found that people in their 60s and older who ate a mostly Mediterranean diet were less prone to mental decline as they aged.
In another study of older Americans, this time living in northern Manhattan, researchers linked Mediterranean-style diets to a 40 percent reduced risk of Alzheimer's disease.
Other studies, however, have not found a connection between Mediterranean eating patterns and cognitive decline with age.
In the new study, led by Emmanuelle Kesse-Guyot at the nutritional epidemiology research center of the French national health research agency INSERM, the investigators used data on 3,083 people who were followed from the mid-1990s, when they were at least 45 years old.
At the beginning of the study period, participants recorded what they ate over one 24-hour period every two months, for a total of six dietary record samples per year.
Then, between 2007 and 2009 when the participants were about 65 years old, their memory and other mental abilities were measured.
Some of the mental tests included asking participants to remember words from a list and asking them to name as many animals as possible in two minutes.
The researchers then separated participants into three categories depending on how closely they adhered to a Mediterranean-style diet, and compared their mental ability test scores.
Overall, the researchers found the people who ate a diet closest to the Mediterranean ideal performed about the same as those who ate a non-restricted diet.
"Our study does not support the hypothesis of a significant neuroprotective effect of a (Mediterranean diet) on cognitive function," wrote the researchers, who did not respond to a request for comment.
Nikos Scarmeas, M.D., who was not involved with the study but has researched the effects of food on brain health, said it's important to note that the new study had some limitations.
For instance, researchers only tested the participants' mental abilities once, making it impossible to track whether they got better or worse over time, said Dr. Scarmeas, an associate professor at New York's Columbia University Medical Center.
"This study will add to the evidence, but we still can't make a conclusion based on this study," Fung.
Dr. Scarmeas agreed it's still too early to recommend a Mediterranean diet to improve or protect brain health.
"We don't have the strong evidence to go and tell people, 'Listen, if you follow this diet, it will improve cognition,'" he said.
Still, neither recommended against it. Both Fung and Dr. Scarmeas said that a Mediterranean diet is tied to better heart health, which some people may find appealing.
© 2023 Thomson/Reuters. All rights reserved.