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Don’t forget the cocoa

Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults. Research shows that chocolate provides a variety of health benefits — many related to cardiovascular health.

Study under review: Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults

Introduction

Chocolate is no longer the bane of acne sufferers everywhere. Instead, research shows that chocolate provides a variety of health benefits, many related to cardiovascular health[1]. It’s thought that these benefits stem from the cacao plant’s flavanol content, varying amounts of which remain after cacao is processed in various ways in order to make chocolate products.

Flavanols are a subset of a larger category of plant compounds called flavonoids. Flavonoids actually used to be referred to as “vitamin P” in the first half of the 1900s, due to reducing the permeability of capillary membranes and thus limiting bleeding. This function was coincidentally uncovered by Albert Szent-Györgyi, who also discovered vitamin C.

While flavanols are commonly mentioned in association with cacao products, they are also found[2] in teas, beans, fruits, berries, and red wine. They have antioxidant and vasodilating[3] properties, both of which may contribute to the coronary benefits observed in previous studies. The higher the cacao content in chocolate, the more flavanols it contains. Cocoa powder and unsweetened baking chocolate rank highest for flavanol content (and are also the least palatable), followed by dark chocolate, and finally milk chocolate, with the lowest flavanol content. Cacao is the plant source with the highest concentrations[4] of one particular type of flavanol, (-)-epicatechin.

Flavanols, previously called vitamin P, are found in high concentrations in chocolate, tea, fruits, and red wine.

Because of the vasodilating properties of flavanols, it’s been hypothesized that flavanols may provide benefit for people suffering from other conditions related to blood flow, particularly in the brain. Alzheimer’s disease is characterized by a reduction of cerebral blood flow, brought on by neurodegeneration from amyloid beta and tau accumulation. Brain functions like memory and cognition also rely on blood flow to the brain. It’s hypothesized that increased blood flow, through either supplementation or aerobic exercise, may improve certain aspects of memory function.

The hippocampus is a critical brain region for short and long term memory formation. The hippocampus has different structural regions. One region to be aware of in the context of this study is the dentate gyrus. The dentate gyrus is where activity localizes during pattern separation[5], which is when the brain tries to determine if two images are the same, or different. This area is also hypothesized to be related to age-related memory loss. The nearby entorhinal cortex, by contrast, is responsible for delayed (in other words, after a period of time, rather than immediately) retention and recall. Deterioration of this region of the brain is connected to Alzheimer’s disease[6].

This study centered around distinguishing blood flow between these two areas of the hippocampus via functional MRI, or fMRI. An fMRI pairs magnetic resonance imaging with a particular task in order to determine what area of the brain is working to complete that task, by detecting changes in blood flow. The researchers then attempted to demonstrate that improving blood flow to the brain through flavanol supplementation and aerobic exercise would improve those particular functions.

Who and what was studied?

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The big picture

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Other Articles in Issue #02 (December 2014)