Flavanols are a class of molecules present in a wide variety of common fruits and vegetables, and most notably in the cocoa beans from which we get chocolate.



In a recent Nature Neuroscience research paper, Professor Scott Small of Columbia University and colleagues, present the results of their investigations into the effects of dietary cocoa supplements on cognitive function. These supplements are rich in flavanols. The researchers related this specifically to enhanced function of a region of the hippocampal formation (part of the cerebral cortex) called the dentate gyrus (DG).



The significance of focusing on the dentate gyrus is that the functional activity of this hippocampal region has been previously shown to be associated with cognitive function affected by age-related decline. Thus, it was hypothesized that interventions capable of enhancing dentate gyrus function, would also enhance cognitive function.



In a randomized double-masked (double-blind) trial, 50-69-year-old adults (n = 41) consumed, for 3 months, a diet that had either high or low cocoa-based flavanol content. The participants were subjected to fMRI scans, in conjunction with cognitive test tasks, to assess changes in the activity of their dentate gyrus.



The cognitive tasks employed involved novel object recognition, and were designed (and have been previously shown) to test age-related hippocampal dysfunction. This essentially involved viewing a complex object and, following a delay, shown the original object and one very similar to it, after which, they were tasked to identify the original.



Based on the results of the cognitive testing, and correlated fMRI imaging of the dentate gyrus, it was found that the participants who consumed the high-flavanol diet showed both enhanced dentate gyrus function, and improved cognition. The authors of the study were thus able to establish that DG dysfunction is an underlying driver of the cognitive decline associated with normal aging. The researchers, went on to suggest that non-pharmacological dietary interventions are capable of reducing (if not preventing) this decline.