Green Tea Could Help Combat Effects Of Stress And High-Fat Foods, Study Suggests

Cocoa or green tea could counter the negative effects of high-fat food which tend to worsen during times of stress, a new study has found. Researchers said that food choices made while feeling stressed can influence how stress impacts heart health. The team from the University of Birmingham, UK, found that while high-fat foods can negatively affect the function of blood vessels and oxygen reaching the brain, flavanol-rich cocoa and green tea can protect vascular function (vessels) during periods of everyday stress.

"We took a group of young healthy adults and gave them two butter croissants with 10 grams salted butter, 1.5 slices of cheddar cheese and 250 millilitres whole milk as breakfast and either a high-flavanol cocoa or a low-flavanol cocoa drink," first author Rosalind Baynham, University of Birmingham, explained. "Following (an eight-minute-long) rest period, 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," Baynham said.

During the resting period and the maths test, blood flow in the forearm, cardiovascular activity and oxygen reaching the brain's prefrontal cortex were measured. "We also measured vascular function using Brachial Flow-mediated dilatation (FMD), which is a prognostic measure for future risk of cardiovascular disease. This stress task induced significant increases in heart rate and blood pressure, similar to the stress you may encounter in daily life," Baynham said.

The team found that consuming fatty foods with the low-flavanol drink when mentally stressed reduced vascular function and lasted up to 90 minutes after the stressful event was over. The findings also showed that the high-in-flavanols cocoa drink was effective at preventing the decline in vascular function following stress and fat consumption. The researchers had previously found that high-fat foods weakened the delivery of oxygen to the brain, during stress.

However, cocoa flavanols did not improve oxygen levels in the brain or impact one's mood, the researchers said. "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 author Catarina Rendeiro, an assistant professor of nutritional sciences at the University of Birmingham.