Q&A: Flavanols in cocoa may help improve brain function, cognition

Cocoa flavanols may help adults’ brains recover from mild vascular challenges quicker and help them perform better on cognitive tests, according to research published in Scientific Reports.

Researchers conducted a randomized, double-blind, within-participant, placebo-controlled study that included physiological and cognitive challenges to evaluate whether the physiological effects of cocoa flavanols impact cerebral and peripheral vascular function and cognition.

They measured cerebrovascular reactivity using a breathing challenge before and after 18 participants received either the high- or low-flavanol cocoa drinks at two visits that were at least 2 weeks apart. Participants then had a third visit where they had structural MRI brain scans. At the beginning of each visit, the researchers assessed participants’ diastolic and systolic BP, brachial artery flow-mediated dilation and frontal cortex oxygenation/deoxygenation at rest and during the breathing challenge.

In the breathing challenge, which took place 2 hours after cocoa consumption, participants breathed in air containing 5% CO₂, approximately 100 times more than normal air.

Researchers found that most participants had stronger, faster brain oxygenation responses after consuming high-flavanol cocoa compared with baseline or low-flavanol cocoa.

Additionally, researchers found that participants had better performance on the most challenging cognitive tests and solved problems 11% quicker than they did at baseline or after low-flavanol cocoa. The researchers did not identify a measurable difference on performance of easier tasks.

Healio Primary Care spoke with study coauthor Catarina Rendeiro, PhD, MSC, researcher and lecturer in nutritional sciences at the University of Birmingham in the U.K., to learn more about the findings and what PCPs should know about dietary flavanols.

Q: What led you to study the impact of cocoa flavanols specifically?

A: For the last 10 to 12 years, I have been interested in the health benefits of plant-derived flavonoids, particularly their effects on brain and cognitive function. We have known for many years that flavanols from cocoa, in particular, can improve vascular function in humans by improving vessel/arterial function. These benefits are apparent even after one single dose. However, the extent to which some of these benefits could translate into the brain vasculature were less clear. The goal of this study was to investigate whether benefits of cocoa flavanols could improve function of the cerebral vasculature and cognitive function.

Q: How do these findings compare with other studies on dietary flavanols?

There are only a handful of studies that looked at the beneficial effects of cocoa on brain function in humans by looking simultaneously at cognitive function and the underlying vascular physiology. Some previous studies show encouraging cognitive benefits, whilst others fail to do so. This variability might be related to the level of the difficulty of the cognitive test used. What we showed in our study is that only when the levels of cognitive challenge are substantially high do we see benefits of cocoa flavanols. This suggests that only when the oxygenation demands in the brain are high enough, a young healthy brain can actually benefit from the intake of flavanols. This is also the first study to show clearly the hemodynamics of brain blood oxygenation after intake of flavanols, leading us to find that flavanols help the brain react more efficiently when challenged with a carbon dioxide breathing test. Not only flavanols increase the total levels of blood oxygenation, but they lead to faster (1 minute faster) oxygenation compared to a low-flavanol placebo.

Q: Based on the findings, should physicians recommend increased cocoa flavanol intake for certain patients to improve brain function?

A: Recommending a diet rich in flavanols would be advisable, eg grapes, green tea, apples, berries, pulses and unprocessed cocoa powders. Many people tend to associate the benefits of cocoa with chocolate, but those are two very different things. The cocoas that contain flavanols are normally unprocessed; however, when you process cocoa beans to make chocolate (roasting, alkalization, etc.), the flavanol content declines. Unfortunately, it is difficult to know what the content of flavanols is in chocolate products as these are not disclaimed in labels. Producing chocolate in ways that retain the content of flavanols should be a goal, so we can obtain effective doses of flavanols from small amounts of chocolate (1-2 squares).

Q: What additional research is needed to determine the role of cocoa flavanols in brain oxygenation and cognition in adults?

A: In order to extrapolate these results to the whole population, we need to extend these studies to other portions of the population (other than young men), including women, middle-aged and older adults. We also only looked at levels of brain oxygenation in the frontal areas of the brain, and although the effects seem to be similar across this area, we do not know whether the same effects will be found in other areas of the brain.