CVD is responsible for 48% of all deaths each year in Europe. Endothelial cell dysfunction is key in early stage development of atherosclerosis leading to CVD. Vascular reactivity and arterial stiffness measured in vivo can be used as markers for general vascular dysfunction. Epidemiological studies indicate that diets rich in fruits and vegetables (F&V) are associated with reduced risk of CVD. However, the relationship between the type and amount of F&V consumed and CVD risk reduction has not been established. Increasing evidence suggests that dietary flavonoids may explain some of the CVD benefits of increased F&V intake. However, this hypothesis had not previously been tested in an adequately powered, dose-response dietary intervention trial.