The Cardiovascular Benefits of Dark Chocolate Supplementation before High-Intensity Resistance Exercise in the Early Follicular and Mid-Luteal Phases of the Menstrual Cycle
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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 (conducted at National Chung Cheng University, Sep–Dec 2023). Participants consumed either 85% dark chocolate or milk chocolate (1 g/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 h 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.
Trial Registration
ClinicalTrials.gov, NCT06908941. Registered 19 March 2025 — Retrospectively registered, https://clinicaltrials.gov/study/NCT06908941 .
