While high-fat foods can negatively affect vascular function and oxygen delivery to the brain during periods of stress, flavanol compounds found in cocoa or green tea can help to protect vascular function during high-stress periods, concluded a new University of Birmingham study published in Food and Function.
 
“We know that when people are stressed, they tend to gravitate toward high-fat foods. We have previously shown that fatty food can impair the body’s vascular recovery from stress. In this study, we wanted to see if adding a high flavanol food to the fatty meal would alleviate the negative impact of stress on the body,” said Catarina Rendeiro, PhD, assistant professor in nutritional sciences at University of Birmingham, in a statement.
 
The researchers gave the 23 participants of the study a high-fat (56.5 grams) meal, with either a high- or low- flavanol cocoa drink, 90 minutes before they took part in an 8-minute mental stress task. During an 8-minute rest period and an 8-minute stress task, the researchers measured forearm blood flow, cardiovascular activity, and prefrontal cortex tissue oxygenation, along with vascular function via brachial flow-mediated dilation (FMD), which is a prognostic measure for future heart disease risk, according to lead author Rosalind Baynham. “The stress task induced significant increases in heart rate and blood pressure, similar to the stress you may encounter in daily life.”
 
The cocoa beverages were created by dissolving 12 grams of cocoa powder into 250 ml of whole milk. The low-flavanol powder was alkalinized, reducing the total flavanols to 5.6 mg, while the non-alkalinized cocoa powder contained 695 mg of total flavanols per serving.
 
Consuming fatty foods with the low-flavanol drink while mentally stressed reduced global measures of vascular function and FMD, and the declines lasted for up to 90 minutes after the stressful event was over. Meanwhile, vascular function remained consistent among the group of participants that had a high-flavanol beverage, and they also had significantly higher FMD. However, cocoa flavanols didn’t improve cerebral oxygenation, or impact mood.
 
“This research shows that drinking or eating a food high in flavanols can be used as a strategy to mitigate some of the impact of poorer food choices on the vascular system. This can help us make more informed decisions about what we eat and drink during stressful periods,” said Rendeiro.