Following a Mediterranean diet — rich in vegetables and fruits, olive oil, beans and legumes, lean sources of protein, and whole grains — has been linked to a number of health benefits, including reduced liver fat, a lower risk of depression, and better kidney health. Because it’s healthy, easy to follow, and satisfying, the Mediterranean diet is often named the best diet to follow for most people.
Recently, the Mediterranean diet has also been tied to improved cognitive performance in people with diabetes — demonstrating that it may help offset some of the increased risk of cognitive impairment linked to diabetes and elevated blood glucose levels. Now, a new study sheds light on what components of the Mediterranean diet may be most responsible for its cognitive benefits.
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Green leafy vegetables, low meat consumption most beneficial
The study, published in the journal Experimental Gerontology, is somewhat unique in that it compared dietary patterns with not just cognitive performance tests, but also neuroimaging tests — showing how the brain functions differently in people who follow different diets. It included 511 participants, all of them 79 years old, who completed a 130-item food frequency questionnaire administered by researchers at the University of Edinburgh in Scotland.
Participants were given a range of cognitive tests that measured processing speed, memory, verbal ability and visuospatial ability (how well you recognize relationships between objects in space). Some of them also had their brain volume and white matter analyzed in magnetic resonance imaging (MRI) scans.
The researchers used results from the questionnaire to assign certain participants to groups based on their eating patterns. In particular, they identified a Mediterranean-style eating pattern, as well as a processed food eating pattern. Based on these groupings, the researchers found that a Mediterranean-style eating pattern was linked to better verbal ability, but not the other measures of cognitive ability or overall (global) cognitive function. But the researchers did find that certain individual components of a Mediterranean diet — green leafy vegetable intake, and less consumption of red meat — were linked to better overall cognitive function.
In contrast, the researchers found that a processed food eating pattern was linked to lower cognitive scores, but that this link became weaker when they adjusted for participants’ cognitive ability during childhood. After this adjustment, a processed food eating pattern was only significantly linked to worse verbal ability. Neither dietary pattern was linked to differences in brain volume or the detailed structure of white matter in the brain.
“Eating more green leafy vegetables and cutting down on red meat might be two key food elements that contribute to the benefits of the Mediterranean-style diet,” wrote study coauthor Janie Corley, PhD, in a news release. But for now, it’s unclear how these dietary patterns might help the brain function better. “In our sample, the positive relationship between a Mediterranean diet and thinking skills is not accounted for by having a healthier brain structure, as one might expect,” Corley noted.
A window into why the Mediterranean diet works
The results of this study offer some clues about what elements of the Mediterranean diet are most important when it comes to cognitive health. Out of all the separate elements of a Mediterranean-style eating pattern, only a higher intake of green leafy vegetables and a lower intake of red meat were linked to overall cognitive function. The results also show that verbal abilities appear to be most affected — positively or negatively — by either a Mediterranean diet or a diet high in processed foods.
It’s important to note that this study looked only at older adults of a specific age. It’s possible that dietary components could have somewhat different effects at different ages.
It’s also worth keeping in mind that different aspects of the Mediterranean diet might have different health effects — for example, this study didn’t examine potential benefits like liver or kidney health, or cardiovascular health, which might be linked to specific elements of the Mediterranean diet. But when it comes to brain health, if you’re deciding what parts of the Mediterranean diet are most important to focus on, the answer appears to be more green leafy vegetables and less red meat.
Want to learn more about the Mediterranean diet? Read “Five Reasons to Try the Mediterranean Diet” and “Eating Patterns and Type 1 Diabetes: Mediterranean Diet,” then watch “What Is the Mediterranean Diet?”