Abstract
Sir Ilya Arts and colleagues (Aug 7, p 488) report that chocolate and tea may contribute significantly to total dietary catechin intake (20% and 55%, respectively).
However, their methods only took into account the monomeric catechins and neglected the more abundant oligomers found in chocolate,2 which are present in only minor concentrations in tea.
Indeed, Arts and colleagues' method to determine catechin content illustrates a commonly encountered difficulty when trying to assess total dietary intake of flavonoids. The commonly used reverse-phase high-performance liquid chromatography techniques are superior for the separation of simple flavonoids, such as those found in tea. However, they are insufficient for analysis of larger oligomeric procyanidins, such as those found in cocoa and chocolate, and normal-phase chromatography is better suited.3 Adamson and colleagues have shown that the monomers (−)-epicatechin and (+)-catechin, are only a fraction of the total quantifiable procyanidins in cocoa and chocolate.4 Hence, the total concentrations of procyanidins in chocolate may have been substantially underestimated by Arts and colleagues.
