Absorption and Urinary Excretion of Peptides after Collagen Tripeptide Ingestion in Humans

Collagen tripeptide (CTP) is a collagen hydrolysate containing a high concentration of tripeptides with a Gly-X-Y sequence, such as Gly-Pro-Hyp. To test the effects of this preparation, we compared the absorption of peptides in humans after ingestion of a tripeptide fraction of CTP (CTP-100), a CTP preparation containing ca. 50% Gly-X-Y tripeptides (CTP-50), and a collagen peptide that did not contain tripeptides (CP). The postprandial levels of Gly-Pro-Hyp and Pro-Hyp in the plasma increased in those subjects who ingested CTP-100 and CTP-50, and were higher with greater Gly-Pro-Hyp ingestion. This demonstrated that collagen hydrolysates were efficiently absorbed when the collagen was ingested in the tripeptide form. Gly-Pro-Hyp and Pro-Hyp were also found in the urine after ingestion of CTP-100 or CTP-50. Similar to the results for the plasma concentration, the urinary excretion of Gly-Pro-Hyp and Pro-Hyp was also dependent on the amount of Gly-Pro-Hyp ingested. This indicates that ingested Gly-Pro-Hyp and generated Pro-Hyp were relatively stable in the body and were transported to the urine in the peptide form. The concentration of Hyp-Gly in the plasma was low after the ingestion of CP and CTP-100 but higher after the ingestion of CTP-50. Overall, our results suggest that tripeptides derived from collagen are absorbed efficiently by the body.