The cardiovascular benefits of dark chocolate supplementation during high-intensity resistance exercise in the early follicular and mid-luteal phases of the menstrual cycle

Abstract Background: Dark chocolate, rich in flavanols, may support vascular health by reducing arterial stiffness and blood pressure across menstrual phases. This study examined the effects of 85% dark chocolate on nitric oxide (NO) levels and vascular function during high-intensity resistance exercise in healthy women across the early follicular and mid-luteal phases. Methods: Thirty-one healthy women (aged 20–30 years) with regular menstrual cycles completed a randomized, crossover study. Participants consumed either 85% dark chocolate or milk chocolate (1g/kg body weight) before high-intensity resistance exercise during the early follicular (days 2–5) and mid-luteal (days 18–24) phases of two menstrual cycles. Finger-toe pulse wave velocity (ftPWV), arterial stiffness, blood pressure, and plasma NO levels were measured at rest, 2 hours after chocolate consumption (baseline), immediately post-exercise (T0), and at 60 (T60) and 120 (T120) minutes post-exercise. Results: Dark chocolate supplementation significantly increased NO levels and reduced systolic blood pressure (SBP), ftPWV, and arterial pressure volume index (API) (p < 0.05) compared to milk chocolate across both menstrual phases. During the early follicular phase, dark chocolate also attenuated exercise-induced increases in arterial stiffness and blood pressure (p < 0.05). Conclusion: 85% dark chocolate supplementation may reduce the negative vascular effects of high-intensity resistance exercise, particularly by lowering blood pressure, arterial stiffness, and API, especially in the early follicular phase. These findings suggest that dark chocolate could be a practical, non-pharmacological intervention for improving cardiovascular health in women.