Daily intake of cocoa or chocolate could improve cognitive performance, especially in vulnerable populations such as the elderly, according to a recent review of literature on the topic.

The treat may have the power to improve cognitive ability, the authors said, because cocoa beans are full of flavanols, which have neuroprotective effects. Dark chocolate is higher in flavanols than milk chocolate.

In the studies examined in the review, flavanols were shown to improve attention, processing speed, working memory and verbal fluency when ingested daily anywhere from five days to three months. The effects were greatest when a person’s memory was beginning to decline or if the person had other mild cognitive impairments.

“This result suggests the potential of cocoa flavanols to protect cognition in vulnerable populations over time by improving cognitive performance,” wrote study authors in the review. “If you look at the underlying mechanism, the cocoa flavanols have beneficial effects for cardiovascular health and can increase cerebral blood volume in the dentate gyrus of the hippocampus. This structure is particularly affected by aging and therefore the potential source of age-related memory decline in humans.”

The beans also could improve working memory performance and visual information processing in the general population, according to the review. And they counteracted the cognitive function effects of a total night of sleep deprivation in women.

As to whether cocoa should become a dietary supplement to improve cognition, the authors said that “regular intake of cocoa and chocolate could indeed provide beneficial effects on cognitive functioning over time,” but they noted side effects such as extra calories and caffeine.

The review was published in Frontiers in Nutrition.