Written by Joyce Smith, BS. The study results showed that the brains of healthy adult participants recovered faster when drinking a flavanol-enriched cocoa beverage prior to a mild vascular challenge, and performed better on complex cognitive tests.
Flavanols are a sub-group of plant flavonoids that give fruits and vegetables their bright colors. They are present in cocoa, grapes, apples, tea, berries, and other foods and are known to benefit vascular function 1-3. Studies have found that, because of their ability to rapidly dilate peripheral arteries within 1-2 hours, flavanols could improve endothelial function in humans 4. This improved endothelial function has been linked to increased nitric oxide (NO) bioavailability 5 which, when compromised, has been shown to contribute to heart disease 6. However, the flavanol effect on brain health and cognitive function is not well understood. While existing evidence suggests that cocoa flavanols may increase NO bioavailability, new evidence suggests a protective role of plant flavanols in cognitive decline 6,7.
In a randomized double-blind placebo controlled study 8 of healthy young adults, researchers investigated whether flavanols in cocoa would increase circulatory levels of NO to benefit the brain vasculature, and positively impact cognitive performance in humans by providing faster and greater brain oxygenation during hypercapnia (high blood levels of carbon-dioxide [CO2]).
Eighteen healthy nonsmoking males, aged 18–40 years, underwent a carbon-dioxide (CO2) challenge. By breathing 5% carbon-dioxide (which is 100 times the normal air concentration) they were able to increase their CO2 blood levels and induce hypercapnia. The CO2 challenge is a standard method for challenging brain vasculature to determine how well it responds to elevated brain CO2 levels. Typically the body responds by increasing oxygenated blood flow to the brain, thus allowing the brain to release excess carbon dioxide. In this study, non-invasive near-infrared spectroscopy, a technique that uses light to capture changes in blood oxygenation levels, was used to track the increases in brain oxygenation in the frontal cortex in response to the CO2 challenge, allowing researchers to measure the brain’s resilience to excess carbon dioxide. Each participant underwent the test before and after drinking a cocoa drink on two separate occasions. On one of those occasions, the drink was enriched with flavanols. Following the carbon dioxide test, the participants were also asked to complete a number of progressively complex cognitive tests.
When participants drank the flavanol-enriched cacao they reached a significantly higher blood oxygenation response to hypercapnia, with oxygenation levels that were achieved faster and were up to three times higher than when they drank the non-flavanol-enriched drink (F(1,16) = 6.08, p = 0.025). High-flavanol cocoa consumption provided maximal oxygenation levels that were more than three times higher than the low-flavanol cocoa (t(16) = − 2.37, p = 0.030) and that reached 90% maximal oxygenation about one minute faster (F(1, 16) = 13.61, p = 0.002). The flavanol-enriched drink also allowed participants to perform cognitive tasks significantly faster (an average of 11% faster) and with greater accuracy. However, the flavanol benefits were evident only for the more difficult tests.
Researchers suggest that the mechanism involved in achieving greater efficient tissue oxygenation after flavanol intake might be similar to the mechanism of NO2 release detected in the peripheral vasculature, where, in this study, hypercapnia induced increases in NO release from the vessel endothelium in the cerebral arteries 9.
Dietary strategies utilizing plant-derived flavanols for improving blood oxygenation and cognitive performance may be of benefit to higher risk populations (e.g., smokers; hypertensives; diabetics; older adults) or those with brain disease or injuries. Future research should definitely focus on identifying the populations that could benefit most from these interventions.
Source: Gratton, Gabriele, Samuel R. Weaver, Claire V. Burley, Kathy A. Low, Edward L. Maclin, Paul W. Johns, Quang S. Pham, Samuel JE Lucas, Monica Fabiani, and Catarina Rendeiro. “Dietary flavanols improve cerebral cortical oxygenation and cognition in healthy adults.” Scientific reports 10, no. 1 (2020): 1-13.
© The Author(s) 2020. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License http://creativecommons.org/licenses/by/4.0/
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Posted December 21, 2020.
Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.
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