Sticking to a Mediterranean diet may not just be good for your heart, it may be good for your brain as well, according to a new study.

Researchers in Spain followed more than 1,000 people for six and a half years, and found that participants who were on a Mediterranean diet and supplemented that diet with extra nuts or olive oil performed better on cognitive tests at the end of the study period than the control group, which followed a lower-fat diet. The study was published Monday in the Journal of Neurology, Neurosurgery and Psychiatry.

"We found that a Mediterranean diet with olive oil was able to reduce low-grade inflammation associated with a high risk of vascular disease and cognitive impairments," said Dr. Miguel Martinez-Gonzalez, the chairman of preventive medicine at the University of Navarra in Spain and a study author.

The Mediterranean diet is devoid of processed foods and bad fats, and high in whole grains, nuts, fruits and vegetables, legumes, fish and even red wine - all things that are high in antioxidant and anti-inflammatory compounds. These types of foods are known to help reduce vascular (circulatory) damage, inflammation and oxidative (free radical) damage in the brain.

But there are limitations to the study.

Dr. Dean Ornish, a well-known proponent of a very low-fat, largely plant-based diet says while the Mediterranean diet is good, it's unfair to compare it to a "low fat diet" in this particular study.

"It's erroneous to say (the Mediterranean diet in this study is) better than a low fat diet, when in fact they weren't following a low-fat diet," said Ornish. "If they said the Mediterranean diet improves cognition compared to standard American diet or standard Spanish diet, I would agree, but clearly, a 37% fat diet is not a low-fat diet."

Ornish, who recommends a diet that includes only 10% fat says in his studies, says he has seen similar effects - improved cognition, improved heart health and reduced depression.

"Good shouldn't be confused with optimal," when referring to the Mediterranean diet, he says.

Dr. Melina Jampolis, a physician-nutrition specialist, says the study findings are encouraging.

"The Mediterranean diet is high in antioxidants, it's anti-inflammatory, and it has a lot of vascular protective elements, so I don't think this is a stretch," said Jampolis. "In a high-risk vascular population, this could be beneficial, and it's worth evaluating further."

But she cautions that the Mediterranean diet should be stacked up against the typical American diet to get a true picture of how much it helps cognition.

While Dr. Martinez-Gonzalez agrees that the study isn't perfect, he says there is clear evidence that the Mediterranean diet is beneficial.

"The quantity of the difference between the groups was small from a clinical point of view, but it was statistically significant," he said. "The harmony, the combination of all of the micronutrients, when they are combined in traditional Mediterranean cuisine, is very important for the functioning of the central nervous system."

And he added that this is not only a healthy diet, it's a sustainable diet.

"The Mediterranean people enjoy this kind of diet every day," he said. "It is pleasant, it is healthy, it is sustainable, and it is not very expensive."