Study under review: Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults
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. 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 in teas, beans, fruits, berries, and red wine. They have antioxidant and vasodilating 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 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, 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.
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.
Other Articles in Issue #02 (December 2014)
- Interview: Bojan Kostevski, MD
Resveratrol and high-intensity interval training
Resveratrol supplementation does not augment performance adaptations or fibre-type–specific responses to high-intensity interval training in humans.
Diet: The whole is greater than the sum of its parts
Discussing the benefits of food (not just supplements) and diet on health, while examining our diet as a whole.
Of mice and guts (and exercise performance)
Effects of intestinal microbiota on exercise performance in mice.
Quantifying the effect of water intake on mood
Effect of changes in water intake on mood of high and lower water drinkers.
Effects of omega-3s on brain function from infancy to old age
Effect of n-3 PUFA supplementation on cognitive function throughout the lifespan from infancy to old age: a systematic review and meta-analysis of randomized controlled trials.
Gut bugs and fiber: A novel way to keep dyslipidemia at bay?
A systematic review and meta-analysis of the prebiotics and synbiotics effects on glycaemia, insulin concentrations and lipid parameters in adult patients with overweight or obesity.
Vitamin C and E supplementation may hinder strength training
Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training.
Whey and guar gum: unlikely heroes for people with diabetes
Effect of a lose dose whey/guar preload on glycemic control in people with type 2 diabetes- a randomized controlled trial.
Interview: Shou-Ching Jaminet, Ph.D., Cancer Researcher
Shou-Ching is a molecular biologist and cancer researcher at Beth Israel Deaconess Medical Center and Harvard Medical School, and Director of BIDMC’s Multi-Gene Transcriptional Profiling Core.