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Mental stress negatively affects the cardiovascular system, inducing a wide range of impairments in vascular function. In fact, exposure to even a single-episode stressor, such as a natural disaster or other traumatic situation, can trigger an acute cardiovascular event. Findings from a new study suggest that consuming cocoa can protect vascular function during a stressful event.

Cocoa is derived from the cacao tree and is the principal component of chocolate. It is rich in flavanols, a class of bioactive compounds found not only in cocoa but also in apples, berries, grapes, and tea. Flavanols are potent antioxidants that exert cardioprotective effects in humans.

The cross-over intervention study involved 30 healthy young males between the ages of 19 and 36 years. After an overnight (12-hour) fast, the participants consumed a cocoa beverage prepared with 8.3 grams of either high- or low-flavanol cocoa powder dissolved in 300 milliliters of low-nitrate water. The high-flavanol cocoa provided approximately 681 milligrams of flavanols, while the low-flavanol cocoa provided approximately 4 milligrams of flavanols. Then they took an eight-minute Paced Auditory Serial Addition Test, a measure of attention and vigilance. At various timepoints surrounding the test, the authors of the study measured aspects of the participants' vascular function, including heart rate, blood pressure, flow-mediated dilation, forearm blood flow, and heart rate variability. Participants repeated the test one week later with the opposite form of the beverage consumed in the first intervention.

The authors found that several measures of vascular function were improved when participants consumed the high-flavanol beverage. Flow-mediated dilation was impaired 30 minutes after the stressor in both groups of participants, but to a lesser degree among those who consumed the high-flavanol beverage. This difference was maintained even at 90 minutes after the stressor. Consuming high-flavanol cocoa improved forearm blood flow before and during the stressor. Stress-induced increases in heart rate, heart rate variability, and blood pressure were similar with both high- and low-flavanol cocoa beverages.

These findings suggest that cocoa, a flavanol-rich food, modulates the cardiovascular responses to stress. Check out this recipe for a flavanol-rich smoothie.

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