The Effect of a Single Dose of Dark Chocolate on Cardiovascular Parameters and Their Reactivity to Mental Stress

Objective: This study investigated the effect of a single administration of dark or milk chocolate on blood pressure (BP), heart rate (HR), and double product (DP) in young healthy women at rest and during acute mental stress.Method: Measurements consisted of anthropometry, BP, and HR. Mean arterial BP (MAP) and DP were computed. The relative reactivity of individual variables was quantified as to their percentage change during the rest or test of mental arithmetic (MA) with respect to the respective baseline value. All subjects underwent two tests of MA-one before chocolate administration and the second one 2 hours after chocolate (1 mg/g of body weight) ingestion.Results: Two hours after ingestion at rest, dark chocolate administration resulted in a significant increase in relative values of systolic BP and DP by 5.1% ± 1.4% and 13.7% ± 3.2%, respectively, compared to the responses in the milk chocolate group (-2.4% ± 1.6% and 0.6% ± 3.4%, respectively, p < 0.04 for both comparisons) without changes in diastolic BP, HR, and MAP. During MA-induced acute stress, the relative magnitude of the reactivity of diastolic BP, HR, MAP, and DP decreased by about 10, 16, 8, and 23 percentage points, respectively, 2 hours after ingestion of dark chocolate compared to the relative reactivity determined before dark chocolate ingestion. Milk chocolate failed to affect any of the above-mentioned parameters at rest or during stress.Conclusions: The single oral intake of 85% dark chocolate increased relative values of systolic BP and DP at rest but buffered the reactivity of diastolic BP, HR, MAP, and DP during mental stress, which was not found after ingestion of milk chocolate. Thus, dark chocolate might have a beneficial effect during acute stress due to its ability to buffer cardiovascular reactivity in young healthy women.