Just this month, a study came out finding that healthy diets help reduce the risk of cognitive decline. While that study only indicated an association between a healthy diet and brain function (and not a cause-and-effect relationship), a new controlled trial now provides evidence that a Mediterranean diet (one form of a healthy diet) may directly contribute to protecting the brain. 

Published in JAMA Internal Medicine, the trial divided 447 older men and women (average age of 66) into three groups: one group was placed on a Mediterranean diet emphasizing lots of fruits, vegetables, lean meats, and supplemental servings of extra-virgin olive oil (about 9 tablespoons per day) ; a second group was placed on the same diet but with a supplemental blend of walnuts, almonds, and hazelnuts (about 30 grams per day); and a third group was placed on a relatively low-fat diet. Although the participants were cognitively healthy, they all had a high risk for cardiovascular health problems. The researchers performed a variety of memory and cognitive tests at the beginning and end of the study, and after tracking the participants for about four years (334 participants completed the study), here is what they discovered:

• Compared with the low-fat diet group, those eating a Mediterranean diet plus extra servings of nuts had a statistically significant increase in their memory composite score. A composite score is one where you add the results from a few tests together.
• Compared with the low-fat diet group, those eating a Mediterranean diet plus supplemental servings of olive oil had a greater improvement in their front and global cognition composite scores.
• In fact, the low-fat diet group experienced a decrease in each cognitive composite area (memory, and frontal and global cognition).

Despite the beneficial effects of the Mediterranean diet, however, it appears that slightly more cases of mild cognitive impairment developed in the olive oil group, making the findings slightly more difficult to interpret. Further, it is difficult to pinpoint exactly what items in the Mediterranean diet may have had a protective effect on brain function. Researchers involved in the new study speculate that a variety of antioxidant and anti-inflammatory foods in the diet, including both olive oil and nuts, play an important role in protecting the brain.

Source: JAMA Internal Medicine