ABSTRACT
This study has examined the effects of type of dairy product (whole milk, skim milk, heavy cream) and chocolate matrix (baking, dark, dairy milk, white) on the oral absorption of the chocolate flavanols (+)-catechin and (-)-epicatechin in a small animal model. In the study, each flavanol compound, as a solution in water or a dairy product or as a chocolate dispersion in water, was administered intragastrically to male Sprague-Dawley rats in an amount equal to or equivalent to 350 mg/kg. In each instance, blood samples were collected over a 5 h period, and used to measure plasma total catechin concentrations by HPLC after enzymatic hydrolysis of flavanol conjugates. Pharmacokinetic data were evaluated using a one compartment approach. Whole milk and heavy cream, and to a much lesser extent skim milk, lowered the oral absorption of both (+)-catechin and (-)-epicatechin and altered the AUC, C(max), k(a), k(e) and t1/2 values in direct proportion to their fat, but not to their protein, content. In addition, the t(max) for solutions of (-)-epicatechin in water and skim milk occurred 2 h earlier than from solutions in whole milk and heavy cream. Similarly, dispersions of baking chocolate in water and in whole milk yielded plasma levels of monomeric catechins that were, respectively, about equal to and much lower than those from aqueous solutions of authentic flavanols. A determining role for a chocolate matrix (dark, dairy milk or white chocolate) on the oral absorption of its constitutive monomeric flavanols was suggested by the apparent variability in plasma total catechins levels that existed among them both before and after their spiking with equal amounts of exogenous (+)-catechin and (-)-epicatechin. Such a variability could reflect differences among different chocolates in terms of their physical properties, matrix components, and matrix characteristics imposed by the manufacturing process used for each type of chocolate. In all the experiments, (+)-catechin demonstrated a higher oral absorption than (-)-epicatechin.