The Mediterranean diet comes with a variety of known benefits, but new research suggests it could also boost brain power if supplemented with nuts or olive oil.

While the supplemented diet appeared to improve cognitive function in older adults living in Spain, the researchers noted further investigation is needed to find a concrete link, the JAMA Network Journals reported.

To make their findings, a team of researchers looked at 447 cognitively healthy volunteers with an average age of 67 who had a high cardiovascular risk and were enrolled in the Prevencion con Dieta Mediterranea nutrition intervention. Out of the sample, 155 participants were assigned to follow the "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."

The researchers looked at cognitive change over time through different neuropsychological tests, specifically pinpointing changes in memory, frontal (attention and executive function) and global cognition.

At the end of a median follow up period of four years (available for 334 participants) the team observed 37 cases of mild cognitive impairment: 13.4 percent of which in the Mediterranean diet plus olive oil group; 7.1 percent in the Mediterranean diet plus nuts group; and 12.6 percent in the low-fat control 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 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," the study concluded.

The findings were published in a recent edition of the journal JAMA Internal Medicine.