Epidemiological studies suggest that certain foods rich in flavanols, including cocoa products, red wine, and tea, are associated with decreased cardiovascular mortality and morbidity. Dietary interventional studies have corroborated this finding and showed that flavanols can acutely and after sustained ingestion improve surrogate markers of cardiovascular risk including endothelial function. Endothelial dysfunction is the key event in the development and progression of cardiovascular disease. The aim of the study is to assess sex specific effects of cocoa flavanols on endothelial and vascular function in healthy subjects.