There’s plenty of evidence that the Mediterranean diet can contribute to a lower risk of heart attacks, stroke, childhood asthma and even cancer. In fact, in a recent study, researchers assessed about 200 traditional Greek Mediterranean foods and reported that taken together, the foods could make 1,024 relevant health claims.
And in May, a team of researchers at the University of Alabama at Birmingham and the University of Athens found that people around age 64 who primarily ate a Mediterranean diet had a lower risk of memory loss.
So perhaps it’s not that surprising that in the latest study, published in the Journal of Neurology, Neurosurgery and Psychiatry, researchers reported similar brain-boosting findings. Except this time, the results showed that the Mediterranean diet was significantly better than a low-fat diet in preserving brain function. The researchers, from the University of Navarra in Spain, studied 522 men and women between the ages of 55 and 80 who did not have heart disease, but were at a higher risk of having circulation-based events like a stroke because of diabetes or a combination of risk factors such as high blood pressure, a family history of stroke, or being overweight.
The participants were split into three diet groups: one consumed a Mediterranean diet with extra-virgin olive oil, another ate a Mediterranean diet supplemented with mixed nuts, and the control group was assigned a low-fat diet. The typical Mediterranean diet includes plenty of olive oil, fruits, vegetables, grains and fish, with moderate amounts of dairy and meat.
All of the participants agreed to complete extensive cognitive tests after about 6½ years, in which the researchers assessed their higher cognitive functions such as their language skills, their ability to orient themselves to time and place, their capacity for abstract thinking and their memory.
By the end of the study, 60 of the participants had developed mild cognitive impairments and 35 developed dementia. Among the participants with mild cognitive decline, 18 consumed the diet with added olive oil, 19 had eaten the diet with additional nuts, and 23 were assigned the low-fat diet. Among the dementia patients, 12 were on the diet with added olive oil, six on the version with added nuts, and 17 were on the low-fat diet.
The cognitive-function tests showed that on average, those consuming either version of the Mediterranean diet scored significantly higher than the low-fat dieters. Because the participants were Spanish men and women, it’s possible that other lifestyle or cultural factors played a role in the results. But even after adjusting for factors such as age, family history of cognitive problems and dementia, education and even depression, which can affect cognitive function, the beneficial effect of the Mediterranean diet remained.
Many studies have linked the diet to health improvements, and researchers are starting to pin down some of the factors that could be driving these effects. In this study, the researchers noted that the Mediterranean diet groups might have exploited the high levels of antioxidants and anti-inﬂammatory agents in the foods.
“Oxidative stress has been associated with neurodegeneration. The main components of the [Mediterranean-diet] intervention in the … trial, extra-virgin olive oil and nuts, have antioxidant properties and, together with other polyphenol-rich foods in the [Mediterranean diet], are suggested to relate to improved cognitive function,” the authors wrote in the study. They also suggested that the beneficial effects of the Mediterranean diet come from improvements in underlying risk factors that otherwise could contribute to strokes or other related health problems.
The study involved a small number of participants, and the volunteers were at higher risk of developing heart or vascular issues, but it did follow them for an extended period of time. So it’s not clear whether the same benefits would hold for the general population, but the researchers say the findings strengthen the link between diet and cognitive function. So far, other studies are also finding similar benefits among Americans favoring the Mediterranean diet, but more studies are needed to assess whether the effects of the diet are universal. If they support these results, however, olive oil and nuts could become useful weapons in holding off age-related cognitive decline.