Urinary excretion of (Epi)catechins in rats fed different berries or berry products

(Epi)catechins are associated with many health benefits in humans. However, their bioavailability, excretory pattern, and extent of conjugation in animals fed different sources or levels in the diet are not well documented. Two experiments were conducted to investigate the urinary excretion of (epi)catechins after feeding of different types of berries or different levels of the same berry source to rats. Experiment 1 investigated the effects of feeding a commercially available concentrated cranberry powder (CCP) at three different levels, 3.3, 6.6, and 33 g/kg of diet, whereas experiment 2 investigated the effect of feeding freeze-dried whole cranberry (CB), blueberry (BB), or black raspberry (BRB) powder at 50 g/kg of diet. Both experiments had an AIN-93-based control and a high-fructose diet (53-65% of the diet) to which was added three levels of CCP in experiment 1 and CB, BB, and BRB in experiment 2. (Epi)catechins were excreted as free and conjugated in both intact and methylated forms. Excretion of conjugated (epi)catechins was as high as 60% of the total consumed in some cases. A majority of both catechins and epicatechins excreted in the urine was in a methylated form. Excretion of epicatechins, including their methylated forms, ranged from 30 to 47% of the ingested amount, whereas that of catechins, including their methylated forms, ranged from 9 to 31%. Urinary excretion of (epi)catechins was dose dependent and increased with the amount of (epi)catechins present in the diet. On the basis of the excretory pattern of (epi)catechins in the urine, data suggested that the bioavailability of epicatechins may be higher than that of catechins and that (epi)catechins may be more available from blueberries compared to cranberries.