Letter to the editor: Caffeine and incident hypertension in women

Dr Winkelmayer and colleagues1 found an inverse U-shaped relationship between habitual caffeine consumption and incident hypertension in a prospective cohort study of US women followed up for 12 years in the Nurses' Health Studies. However, when examining classes of caffeinated beverages, coffee consumption was not linked to an increased risk of hypertension. In contrast, cola beverage consumption was associated with an increased risk, independent of whether it was sugared or diet cola. The authors speculated that the substance responsible for the increased risk of hypertension in the cola drinks is a compound other than caffeine. Caffeine may still be the cause of the hypertension. Coffee has higher caffeine content than cola, and the average US diet receives 71% of its caffeine intake from coffee, 16% from cola, and 12% from tea.2