other flavanol-related changes, such as those in prostaglandin synthesis and thromboxane production (17), have all the biological potential to induce significant modifications of insulin sensitivity, the particular study design that we have adopted minimizes study bias due to confounding factors, including type II statistical error and the order effect. Therefore, whatever the mechanism underlying the observed positive effects exerted by dark chocolate bars on insulin sensitivity, our data are consistent with the fact that increased insulin sensitivity represents a novel potential benefit derived from cocoa. Although we cannot completely exclude the contribution of other substances present in dark but not in white chocolate bars to the positive effects of dark chocolate on insulin sensitivity and blood pressure, it seems extremely likely that flavanols were responsible for the above effects.