The Secret Behind Cocoa's Brain-Boosting Ability

Megan Brooks

December 10, 2020

Increased consumption of cocoa flavanols may improve cognition by boosting brain oxygenation levels, new research suggests.

In a small study of healthy adult men, researchers observed increased brain oxygenation after the men drank a flavanol-enriched cocoa drink, which was associated with better performance on a challenging cognitive task.

"Our results showed a clear benefit for the participants taking the flavanol-enriched drink, [and] we can link this with our results on improved blood oxygenation," lead researcher Catarina Rendeiro, PhD, University of Birmingham, Birmingham, United Kingdom, said in a news release.

The study was published online November 24 in Scientific Reports.

Mechanistic Study

Cocoa flavanols, a subgroup of flavonoids that are also present in berries, grapes, apples, and tea, have been shown to improve endothelial function by enhancing the vasodilatory properties of peripheral arteries.

Emerging evidence also suggests that flavanol-rich diets protect against cognitive aging, but mechanisms remain unclear.

The researchers assessed the underlying acute physiologic actions of cocoa flavanols on cerebrovascular and cognitive function in 18 healthy men, aged 18 to 40 years. The study employed a double-blind, within-subject, placebo-controlled design.

Using noninvasive near-infrared spectroscopy, the investigators observed that for the men who drank the flavanol-enriched cocoa drink, tissue oxygenation in frontal areas of the brain was more efficient during a 5% CO2-breathing challenge (hypercapnia).

"This suggests that, similarly to peripheral vascular benefits, flavanols result in clinically relevant improvements in cerebrovascular reactivity in a healthy brain," they write.

Improved brain oxygenation observed with the flavanol-packed cocoa drink appeared to translate into improved cognitive performance on more complex cognitive tasks. The men performed higher-complexity tasks 11% faster on average after consuming the flavanol-enriched drink. There was no measurable difference in performance on easier tasks.

Of note, say the researchers, four of the men with high initial levels of brain oxygenation responses demonstrated no further gain in blood oxygenation or cognitive benefit from drinking enriched cocoa.

"This may indicate that some individuals that perhaps are already very fit have little room for further improvement," Rendeiro said.

The researchers believe the findings may have implications for the use of dietary strategies containing plant-derived flavanols to enhance blood oxygenation and cognitive performance in healthy populations and perhaps in helping people recover from brain injury and disease.

Durable Effect?

Weighing in on the study for Medscape Medical News, Yuko Hara, PhD, noted that the evidence regarding flavanols for brain health is somewhat "mixed," although some other studies have suggested improvements in certain cognitive functions.

As director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation, Hara and other staff neuroscientists review the potential brain benefits of supplements and foods, including cocoa.

This new study is "elegant and novel," Hara said, "in that it's the first time where they are demonstrating a relationship between the high flavanol content of cocoa with the hemodynamic response, as well as with cognitive benefits."

She cautioned that participants in the study were healthy young adults. "It would be interesting to know if these benefits are seen in older adults who may have impairments in cerebrovascular reactivity. That's still unanswered," said Hara.

Another caveat, Hara said, is that this was a single-dose study of mechanisms, and it's unclear how long the cerebrovascular and cognitive benefits last.

"Is it an acute effect on cognitive performance or are there lasting effects, and could it even prevent cognitive decline and dementia if people take it long term? These are really interesting questions that are unanswered," she said.

The research was funded by a Birmingham-Illinois Bridge Seed Grant and by the US National Institute of Aging. Rendeiro and Hara report no relevant financial relationships.

Sci Rep. Published online November 24, 2020. Full text

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