Food contains the bioactive peptide, cyclo(His-Pro).

Cyclo(His-Pro) (CHP) is a cyclic dipeptide with numerous biological activities. As small di- and tripeptides may be absorbed intact when ingested orally, we were interested in examining several common foods for the presence of cyclo(His-Pro)-like immunoreactivity (CHP-LI). In all foods tested, CHP-LI was found at levels 5-1500 times those previously found in human plasma. This CHP-LI was identical to authentic CHP by immunoidentity and chromatographic behavior. We conclude that 1) CHP-LI is readily detectable in several common food sources; 2) this CHP-LI is indistinguishable from authentic CHP; and 3) it is likely the CHP-LI in foods is absorbed in quantities sufficient to cause elevations of CHP-LI in plasma to biologically significant levels.