Brains of healthy adults recuperated faster from a mild vascular challenge and performed better on difficult tests if the participants ingested cocoa flavanols beforehand, according to a new study. The findings of the new study are published in the journal Scientific Reports.
14 out of 18 participants saw these improvements after consuming the flavanols. Catarina Rendeiro, a researcher and lecturer in nutritional sciences at the University of Birmingham, stated, "Earlier studies have shown that having foods rich in flavanols can help vascular function, but this is the first to discover a positive effect on brain vascular function and cognitive performance in healthy young adults." She headed the research with the University of Illinois at Urbana-Champaign psychology professors Monica Fabiani and Gabriele Gratton.
"Flavanols are small molecules present in many fruits and vegetables, and cocoa, too," Rendeiro said. "They give fruits and vegetables their bright colors, and they are known to help vascular function. We wanted to know whether flavanols also profit the brain vasculature, and whether that could have a positive impact on cognitive function."
The team examined the 18 participants before their intake of cocoa flavanols and in two separate trials. The subjects received flavanol-rich cocoa and another during which they consumed processed cocoa with very low levels of flavanols.
Neither the participants nor researchers knew which type of cocoa was consumed in each of the trials. This double-blind study design prevents researchers' or participants' expectations from affecting the results.
About 2 hours after consuming the cocoa, participants breathed air with 5% carbon dioxide - about 100 times the air's average concentration. This is a conventional method for challenging brain vasculature to determine how well it responds, Gratton said.
The body typically responds by increasing blood flow to the brain, he said. "This brings in more oxygen and also lets the brain to discharge more carbon dioxide," he said.
With functional near-infrared spectroscopy, a technique that uses light to capture blood flow changes to the brain, the team measured oxygenation in the frontal cortex. This brain region plays a vital role in planning, regulating behavior decision-making.
"This allows you to measure how well the brain protects itself from the excess carbon dioxide," Fabiani said.
Researchers also challenged participants with complicated tasks that required them to manage sometimes conflicting or competing demands.
Most of the participants had a more robust and faster brain oxygenation response following exposure to cocoa flavanols than they did at baseline or after consuming cocoa lacking flavanols, the researchers found.
Rendeiro said, "The levels of maximal oxygenation were more than three times higher in the high-flavanol cocoa versus the low-flavanol cocoa, and the oxygenation response was about one minute faster."
After ingesting the cocoa flavanols, participants performed better on the most challenging cognitive tests, correctly solving problems 11% faster than they did at baseline or when they consumed cocoa with reduced flavanols. There was no measurable difference in performance on the more manageable tasks, however.
"This suggests that flavanols might only be useful during cognitive tasks that are more challenging," Rendeiro said.Participants differed in their responses to cocoa flavanols, the researchers found.
"Although most people profited from flavanol intake, there was a small group that did not," Rendeiro said. Four of the 18 study subjects had no significant differences in brain oxygenation response after consuming flavanols, nor did their performance on the tests develop.
"Because these four participants already had the highest oxygenation responses at baseline, this may mean that those who are already quite fit have limited room for development," Rendeiro said. "Overall, the findings suggest that the improvements in vascular activity after exposure to flavanols are connected to the improvement in cognitive function."