Journal of the American College of Nutrition, Vol 15, Issue 2 175-179, Copyright © 1996 by American College of Nutrition

JOURNAL ARTICLE

The bioactive peptide cyclo(His-Pro) may be absorbed following ingestion of nutritional supplements that contain it

H. Mizuma, B. Y. Legardeur, C. Prasad and C. W. Hilton
Department of Medicine, LSU Medical Center, New Orleans 70112, USA.

OBJECTIVE: Food contains a number of peptides with potential bioactivity. We previously found ng/mliter to mcg/mliter quantities of cyclo(His-Pro)-like immunoreactivity in a number of foods and nutritional supplements. A number of activities have been attributed to cyclo(His-Pro) (CHP), including appetite inhibition and inhibition of insulin secretion in vitro. We wondered whether the cyclo(His-Pro)-like immunoreactivity present in nutritional supplements might be absorbed and, if so, whether parameters of insulin secretion would be altered. METHODS: After performing a pilot study which suggested some common nutritional supplements contain CHP, a follow-up study was done to confirm and expand the findings of the pilot study. Eight fasting volunteers ingested approximately 250 mL of a CHP-containing supplement one day, and then an equienergetic CHP-free supplement the next. RESULTS: Blood drawn for CHP, insulin, glucose, and C-peptide a number of times on both days revealed that when volunteers ingested CHP-containing supplements, CHP levels at 120 minutes were significantly higher than baseline (7.69 +/- 0.50 pmol/mL vs. 9.18 +/- 0.48 pmol/mL; p = 0.011 in the CHP group and 7.90 +/- 0.85 pmol/mL vs. 7.22 +/- 0.73 pmol/mL, p > 0.3 in the CHP-free group) and significantly higher than levels achieved when they drank CHP-free supplements. Levels of glucose, insulin, and C-peptide were not different in the two groups. CONCLUSION: CHP in nutritional supplements may be absorbed when ingested orally and does not grossly affect glucose or parameters of insulin secretion.