Mediterranean Diet May Improve Brain Function

The Mediterranean diet has been associated with lower heart disease risk and delaying diabetes, and now new research says that it may also improve brain function.

According to researchers, supplementing the plant-based Mediterranean diet with antioxidant-rich extra virgin olive oil or mixed nuts was associated with improved cognitive performance in a study of older adults in Spain. However, the team is quick to point out that more research is needed to confirm this relationship.

The concept that dietary habits are linked to cognitive performance is nothing new. Oxidative stress - that is, the body's inability to appropriately detoxify itself - has long been considered to play a major role in cognitive decline. Previous research suggests following a Mediterranean diet may relate to better cognitive function and a lower risk of dementia.

But these studies had observational limitations, so this time around researchers compared a Mediterranean diet supplemented with olive oil or nuts with a low-fat control diet.

As described in the journal JAMA Internal Medicine, they conducted a randomized clinical trial including 447 cognitively healthy volunteers who were at high cardiovascular risk and were enrolled in the Prevencion con Dieta Mediterranea nutrition intervention.

Of the participants, 155 individuals were assigned to supplement a Mediterranean diet with one liter of extra virgin olive oil per week; 147 were assigned to supplement a Mediterranean diet with 30 grams per day of a mix of walnuts, hazelnuts and almonds; and 145 individuals were assigned to follow a low-fat control diet.

Using neuropsychological tests that measured memory, frontal (attention and executive function) and global cognition, the researchers determined how participants' cognitive function changed over time.

After an average of four years, follow-up tests showed 37 cases of mild cognitive impairment: 17 (13.4 percent) in the Mediterranean diet plus olive oil group; eight (7.1 percent) in the Mediterranean diet plus nuts group; and 12 (12.6 percent) in the low-fat control group. No dementia cases were documented in patients who completed study follow-up.

Those on the low-fat diet showed a significant decrease in brain function. On the other hand, memory function improved significantly in the Mediterranean diet plus nuts group, while frontal and global cognition improved in the Mediterranean diet plus olive oil group.

"Our results suggest that in an older population a Mediterranean diet supplemented with olive oil or nuts may counter-act age-related cognitive decline," the authors concluded. "The lack of effective treatments for cognitive decline and dementia points to the need of preventive strategies to delay the onset and/or minimize the effects of these devastating conditions. The present results with the Mediterranean diet are encouraging but further investigation is warranted."

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