Flavanol-rich cocoa could protect men from effects of stress

Life’s daily stress was turned up to 11 this past year, and consumers the world over have turned to whatever bits of indulgence they could for momentary escape. But what if that indulgence could help deal with stress on a physiological level? According to a recent study published in Nutrients, that may be the case when it comes to a popular sweet treat: flavanol-rich hot cocoa (2021;13[4]:1103).

Researchers at the University of Birmingham worked with 30 males, ages 18-45. These participants were all healthy males, meaning they did not smoke or overconsume alcohol, and were free of “acute illness or infection; history of cardiovascular, respiratory, metabolic, liver or inflammatory diseases; blood-clotting disorders, allergies or food intolerances; weight-reducing dietary regiment or dietary supplements; long-term medication or antibiotics in the prior three months.”

For the randomized, double-blind, placebo-controlled crossover study, “Participants reported to each laboratory session after a 12-hour fast, having refrained from alcohol, vigorous exercise, and polyphenol-containing foods and drink 24 hours before testing.” Examples of the items avoided included fruits such as oranges, grapefruit and berries; most vegetables, in particular onions, leeks, peppers, tomatoes and beetroot; as well as cocoa, nuts, olive oil, tea and coffee.

Participants were measured for baseline readings in brachial blood pressure (BP), flow-mediated dilatation (FMD) and forearm blood flow (FBF), in this order. After these assessments, participants consumed either a high-flavanol drink or low-flavanol drink. Ninety minutes later, “FBF was measured again during an 8-minute rest period (rest) and during an 8-minute mental stress task (stress). Beat-to-beat BP, heart rate (HR), heart rate variability (HRV) and pre-ejection period (PEP) were recorded throughout pre-intervention baseline, rest and mental stress, and data was analyzed for the minutes during which FBF was taken. Both FBF and cardiovascular variables were averaged across the 4 minutes of data collection to provide an overall pre-intervention baseline, rest and stress value. Brachial BP and brachial FMD were measured 30 (+30) and 90 (+90) minutes post-stress.”

The results showed the high-flavanol hot cocoa had a noticeable effect.

“Cocoa flavanols prevented the decline in brachial FMD 30-minutes post-stress, and FMD remained significantly higher following high-flavanol cocoa compared to low-flavanol cocoa 90-minutes post-stress,” the authors concluded. “Furthermore, high-flavanol cocoa increased FBF at rest and during stress in comparison to low-flavanol cocoa.”

In other words, the high-flavanol cocoa drink improved blood flow and vessel function during times of stress.

“We found that drinking flavanol-rich cocoa can be an effective dietary strategy to reduce temporary impairments in endothelial function following mental stress and also improve blood flow during stressful episodes,” said Catarina Rendeiro, Ph.D., one of the study’s lead authors. “Flavanols are extremely common in a wide range of fruit and vegetables. By utilizing the known cardiovascular benefits of these compounds during periods of acute vascular vulnerability (such as stress), we can offer improved guidance to people about how to make the most of their dietary choices during stressful periods.”

The male-only study does have its limitations, the authors cautioned, and further study on both males and females will be necessary. But for now, take heart knowing that stress-induced bite of chocolate or sip of cocoa might be good not just for the soul, but the body as well.