Epidemiological data suggests that a diet high in polyphenol-rich foods, such as berries and dark chocolate, is associated with lower cardiovascular disease risk.1 ,2 However, it remains unclear if this association reflects a cause-and-effect or whether it is simply due to associated clinical factors. The aim of the Polyphenol Intervention Trial (PPhIT) was to determine if increasing overall polyphenol dietary intake results in improved microvascular function, measured by forearm blood flow (FBF) responses to acetylcholine (Ach), an endothelium-dependent vasodilator (see page 1371). Hypertensive patients (51 per group) were randomized to a high or low polyphenol diet for 8 weeks. The high polyphenol group consumed a daily diet with 6 portions of fruits and vegetables, including one serving of berries, and 50 g of dark chocolate; whereas the low-polyphenol group was asked to avoid these foods. The high polyphenol group had larger increases in plasma vitamin C, serum carotenoids, and plasma epicatechin levels which suggests participants were compliant with the study diet. Forearm blood flow (figure 1) showed a significantly greatly vasodilator response in the high polyphenol group after intervention both when compared to baseline and when compared to the low polyphenol group.⇓