Cocoa and Green Tea May Help Prevent Negative Effects of Stress and Fatty Food

A new study by the University of Birmingham reveals that a flavanol-rich cocoa drink can protect vascular health from the negative effects of stress and high-fat foods. Flavanols, found in cocoa, tea, berries, and certain nuts, are known for their cardiovascular benefits, including regulating blood pressure and maintaining vascular function.

"We know that when people are stressed, they tend to gravitate towards high-fat foods. We have previously shown that fatty food can impair the body's vascular recovery from stress," said Catarina Rendeiro, PhD, assistant professor in nutritional sciences at the University of Birmingham in England. "In this study, we wanted to see if adding a high-flavanol food to the fatty meal would alleviate the negative impact of stress in the body."

For the investigation published in Food & Function, participants consumed a high-fat breakfast with either a high-flavanol or low-flavanol cocoa drink. Then, they had a short mental break followed by a stressful task.

"We asked the participants to complete a mental maths test which increased in speed for eight minutes, alerting them when they got an answer wrong," explained Rosalind Barynham, first author of the paper and PhD student. "During the eight-minute rest period and eight-minute mental maths test, we measured forearm blood flow, cardiovascular activity, and prefrontal cortex (PFC) tissue oxygenation. We also measured vascular function using Brachial Flow-mediated dilatation (FMD), which is a prognostic measure for future risk of cardiovascular disease."

Researchers found that high-flavanol cocoa significantly prevented the decline in vascular function caused by the combination of stress and fatty food. However, the results showed it did not improve cerebral oxygenation or mood.

The research highlights flavanol-rich foods, such as minimally processed cocoa, green tea, and berries, as practical dietary strategies to mitigate stress-related vascular damage. According to the study, nutritional guidelines recommend a daily intake of 400 to 600 milligrams (mg) of flavanols, achievable through tea, fruit, and high-quality cocoa, to support cardiovascular health during stressful periods.

"Modern life is stressful, and the impact of stress on our health and the economy has been well documented, so any changes we can make to protect ourselves from some of the symptoms of stress is positive," said Jet Veldhuijzen van Zanten, MSc, PhD, Professor of Biological Psychology at the University of Birmingham. "For those who tend to reach for a treat when stressed or depend on convenient food because they work high-pressure jobs or are time-poor, incorporating some of these small changes could make a real difference."