Background: Reduction in functional capacity is one of the hallmarks of cardiovascular aging with increasing importance in an aging population worldwide. Flavanols have already demonstrated favorable effects on several cardiovascular health markers. We, therefore, investigated the effect of cocoa flavanols on cardiorespiratory fitness as a surrogate marker for functional status in healthy elderly.

Methods: In a randomized, double-masked, placebo-controlled, parallel-group dietary intervention trial, 68 apparently healthy elderly (55-79 years, 28 female) received either 410 mg of flavanol or a nutrient-matched placebo capsule BID for 30 days. The primary endpoint was defined as cardiorespiratory fitness measured as VO₂peak in a cardiopulmonary exercise test (CPET). Secondary endpoints were oxygen pulse (VO₂/HR), resting blood pressure (BP), exercise heart rate (HR), and resting vascular function measured as flow-mediated vasodilation (FMD).

Results: After 30 days of flavanol intake, VO₂peak rose by 190 ml/min (95% CI 1-371 ml/min) and VO₂peak/kg by 2.51 ml/(min*kg) (95% CI 0.30-4.27 ml/(min*kg)). O₂-pulse increased by 1.74 ml (95% CI 0.29-3.18 ml) and max exercise capacity by 9.6 W (95% CI 2.1-17.7 W). Flavanols decreased resting systolic and diastolic BP by 5.4 mmHg (95% CI (-)10.7-(-)0.1 mmHg) and 2.9 mmHg (95% CI (-)5.5-(-)0.4 mmHg), respectively. FMD increased by 1.28% (95% CI 0.76-1.79 %) in the flavanol group. No changes for primary and secondary endpoints were recorded in the placebo group.

Conclusion: Dietary flavanols improve markers of cardiorespiratory fitness in CPET, highlighting the potential of flavanols to maintain cardiovascular health and fitness in elderly individuals.