Stress damages the heart and blood vessels, increasing the risk of cardiovascular events like heart attack or stroke. Stress can also drive people to make poor dietary choices, often leading to overeating or consuming high-fat, low-nutrient foods instead of healthier options like fruits and vegetables. A recent study found that cocoa flavanols help counteract the harmful effects of stress and unhealthy meals on the heart and blood vessels.

The study involved 23 healthy young adults. Each participant ate a high-fat meal (buttered croissants, cheese, and whole milk) paired with either a high-flavanol cocoa drink or a low-flavanol cocoa drink before completing an eight-minute stress task. Researchers measured their blood vessel function, brain oxygen levels, blood flow, blood pressure, and mood multiple times before and after the stress challenge.

Participants who drank the high-flavanol cocoa maintained better blood vessel function after stress than those who consumed the low-flavanol drink. Blood vessel function declined considerably within 30 minutes of the stress task in the low-flavanol group but was preserved with high flavanol intake. At 90 minutes, blood vessel function improved beyond pre-stress levels in the high-flavanol group. The two groups had similar stress-related changes in blood pressure, brain oxygenation, and mood.

The findings from this small study suggest that flavanol-rich foods help protect the cardiovascular system during stressful periods, even when accompanied by unhealthy meals. Flavanols are polyphenolic compounds in dark chocolate, berries, apples, and tea. Evidence suggests flavanols exert potent antioxidant and anti-inflammatory properties. Learn more about flavanols and other polyphenols in our overview article.