We compared levels of (ϩ)-catechin, (Ϫ)-epicatechin, and their metabolites in rat plasma and urine after oral administration. Rats were divided into four groups and given (ϩ)-catechin (CA group), (Ϫ)-epicatechin (EC group), a mixture of the two (MIX group) or deionized water. Blood samples were collected before administration and at designated time intervals thereafter. Urine samples were collected 0 -24 h postadministration. (ϩ)-Catechin, (Ϫ)-epicatechin and their metabolites in plasma and urine were analyzed by HPLC-mass spectrometry after treatment with ␤-glucuronidase and/or sulfatase. After administration, absorbed (ϩ)-catechin and (Ϫ)-epicatechin were mainly present in plasma as metabolites, such as nonmethylated or 3Ј-O-methylated conjugates. In the CA and MIX groups, the primary metabolite of (ϩ)-catechin in plasma was glucuronide in the nonmethylated form. In the EC and MIX groups, in contrast, the primary metabolites of (Ϫ)-epicatechin in plasma were glucuronide and sulfoglucuronide in nonmethylated forms, and sulfate in the 3Ј-O-methylated forms. Urinary excretion of the total amount of (Ϫ)-epicatechin metabolites in the EC group was significantly higher than the amount of (ϩ)-catechin metabolites in the CA group. The sum of (ϩ)-catechin metabolites in the urine was significantly lower in the MIX group than in the CA group, and the sum of (Ϫ)-epicatechin metabolites in the MIX group was also significantly lower than in the EC group. These results suggest that the bioavailability of (Ϫ)-epicatechin is higher than that of (ϩ)-catechin in rats, and that, in combination, (ϩ)-catechin and (Ϫ)-epicatechin might be absorbed competitively in the gastrointestinal tract of rats.

We evaluated the levels of (-)-epicatechin (EC) and its metabolites in plasma and urine after intake of chocolate or cocoa by male volunteers. EC metabolites were analyzed by HPLC and LC/MS after glucuronidase and/or sulfatase treatment. The maximum levels of total EC metabolites in plasma were reached 2 hours after either chocolate or cocoa intake. Sulfate, glucuronide, and sulfoglucuronide (mixture of sulfate and glucuronide) conjugates of nonmethylated EC were the main metabolites present in plasma rather than methylated forms. Urinary excretion of total EC metabolites within 24 hours after chocolate or cocoa intake was 29.8+/-5.3%'; and 25.3+/-8.1% of total EC intake. EC in chocolate and cocoa was partly absorbed and was found to be present as a component of various conjugates in plasma, and these were rapidly excreted in urine.

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It is possible that increases in HDL-cholesterol concentrations may contribute to the suppression of LDL oxidation and that polyphenolic substances derived from cocoa powder may contribute to an elevation in HDL cholesterol.

The effect of protein fractionation on the bioavailability of amino acids and peptides and insulin response and whether the protein source influences these effects in humans are poorly understood. This study compared the effects of different sources and degrees of hydrolysis of dietary protein, independent of carbohydrate, on plasma amino acid and dipeptide levels and insulin responses in humans. Ten subjects were enrolled in the study, with five subjects participating in trials on either soy or whey protein and their hydrolysates. Protein hydrolysates were absorbed more rapidly as plasma amino acids compared to nonhydrolyzed protein. Whey protein also caused more rapid increases in indispensable amino acid and branched-chain amino acid concentrations than soy protein. In addition, protein hydrolysates caused significant increases in Val-Leu and Ile-Leu concentrations compared to nonhydrolyzed protein. Whey protein hydrolysates also induced significantly greater stimulation of insulin release than the other proteins. Taken together, these results demonstrate whey protein hydrolysates cause significantly greater increases in the plasma concentrations of amino acids, dipeptides, and insulin.

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SummaryWe investigated the effects of fructooligosaccharides (FO) feeding on the absorption of iron (Fe), calcium (Ca) and magnesium (Mg) and on the biochemical parameters in Fe-deficient anemic rats. Fe-deficient anemic rats were made by feeding an Fe-deficient diet for 3 weeks. Then these Fe-deficient rats were fed an experimental diet that contained one of two levels of Fe (15 or 30mg/kg diet), in the form of ferric pyrophosphate, and one of two levels of FO (0 or 50g/kg diet) for 2 weeks. After the rats were fed these experimental diets, FO-feeding increased the hematocrit ratio, the concentration of hemoglobin and the hemoglobin regeneration efficiency during the first week. Also, the apparent absorption of Fe was increased by FO-feeding. The levels of Fe in the diet did not affect the absorption of Ca and Mg. However, FO-feeding increased the absorption of Ca and Mg. FO-feeding lowered the pH and raised the solubility of Fe, Ca and Mg in the cecal contents, suggesting that those increasing effects of FO-feeding on absorption of these minerals is correlated with fermentation of FO in the large intestine, namely, the cecum and colon. We concluded that FO-feeding improved recovery from anemia and increased the absorption of Fe, Ca and Mg in Fe-deficient anemic rats.

We investigated the effects of fructooligosaccharides on the absorption of calcium, magnesium and water from the colon and rectum of rats fed a control diet or the control diet containing 50 g fructooligosaccharides/kg. Chromium-mordanted cellulose was used as an unabsorbable marker to calculate apparent absorption of calcium and magnesium. There was a positive correlation (r = 0.982, P < 0.001 in rats fed the control diet and r = 0.975, P < 0.001 in rats fed the fructooligosaccharides-containing diet) between the amount of chromium and the dry weight of each fecal pellet in the colon and rectum. Ratios of calcium to chromium and magnesium to chromium in fecal pellets in the colon and rectum were calibrated from the Ca:Cr and Mg:Cr ratios of cecal contents. In rats fed the fructooligosaccharides-containing diet, but not in rats fed the control diet, these ratios were correlated with the fractional length of transit along the colon and rectum, indicating linear disappearance of calcium and magnesium during the colorectal passage. Total apparent absorption of calcium and magnesium, predicted from regression equations with the Ca:Cr and Mg:Cr ratios of cecal contents, agreed well with those calculated from the Ca:Cr and Mg:Cr ratios of feces. The consumption of fructooligosaccharides did not affect net water absorption from the colon and rectum. These results indicated that fructooligosaccharides significantly increased calcium and magnesium absorption and that indigestible and fermentable carbohydrate facilitates colorectal absorption of calcium and magnesium.