The stereochemical configuration of flavanols influences the level and metabolism of flavanols in humans and their biological activity in vivo.
Extensive epidemiological and clinical evidence associates diets high in flavanol-containing foods with cardiovascular health benefits in humans. Catechin and epicatechin, the most common flavanolsin foods, are present in the diet in different enantiomeric forms. This study investigated the influence of the stereochemical configuration of flavanols on their absorption, metabolism, and biologicalactivity. Healthy adult males were asked to consume equal amounts of the stereochemically pureflavanols (-)-epicatechin, (-)-catechin, (+)-catechin, and (+)-epicatechin (1.5mg/kg bw) in a well-defined cocoa-based, dairy-containing drink matrix, and flavanol levels were subsequently determined inplasma and 24-h urine. The results obtained show that the stereochemical configuration of flavanolshas a profound influence on their uptake and metabolism in humans. In addition, we assessed the vasodilatory activity of each flavanol stereoisomer in vivo and found (-)-epicatechin to be the single stereoisomer capable of mediating a significant arterial dilation response. Importantly, this effect was independent of the classic antioxidant properties of flavanols. Overall, these results indicate that the proposed beneficial health effects associated with the consumption of flavanol-containing foods will significantly depend on the stereochemical configuration of the flavanols ingested.