Peptides are a collection of amino acids strung together. Put two together, and you have a dipeptide; put three together, and you have a tripeptide. The science of peptides is getting quite interesting. If you go back a couple of decades, you’ll find evidence that peptide length influences absorption in the gut. In one study the influence of the peptide-chain length was analyzed in 12 human subjects. Three hydrolysates of egg white and an equivalent amino acid mixture were compared. Two hydrolysates contained mainly dipeptides and tripeptides; the third had tripeptides to pentapeptides. Nitrogen absorption was significantly slower with the higher-chain-length mixture than with either of the two short-chain mixtures. Several amino acid residues were absorbed less well from the higher-chain mixture. So the study suggests that not all peptides are aborbed easily.1
Another group of scientists tested the effect of chronic supplementation of cysteamine, a degradation product of cysteine, on serum insulinlike growth factor 1 concentrations and growth hormone receptors in pigs. I know, I know. Pigs? Well, pigs respond the way humans do. The results suggest that dietary cysteamine supplementation modulates the growth rate, serum IGF-I concentrations and gene expression of various growth factors.2
Other peptides have been developed to be used in the management of exercise-related disorders. Researchers who looked at a decapeptide isolated from pig spleen found that it had antifatigue effects on mice that had been put on an exhaustive swimming regimen and that it can also reduce the damage to heart and skeletal muscle caused by exercise.3
Another study compared the relative impact of carbohydrate alone and carbohydrate plus peptide glutamine—50 grams of maltodextrin plus 3.5 grams of peptide glutamine in 250 milliliters of water. The researchers found that the combination of carbs and glutamine peptide was better at improving exercise performance.4 Furthermore, in exercised mice, black soy peptides significantly decreased fat mass and bodyweight gain.5
I predict that peptides will become a robust, scientifically supported and dynamic category of supplements very soon. It is clear that not all peptides are created equal. Now we’ve got to figure out which are the most anabolic and which are best at burning fat—and whether any are good at both. IM
Editor’s note: Jose Antonio, Ph.D., is the CEO of the International Society of Sports Nutrition (www.theissn.org) and is a sports science consultant to VPX/Redline.
1 Grimble, G.K., et al. (1987). Effect of peptide chain length on absorption of egg protein hydrolysates in the normal human jejunum. Gastroenterology. 92:136-42.
2 Liu, G., et al. (2008). Effects of dietary supplementation with cysteamine on growth hormone receptor and insulinlike growth factor system in finishing pigs. J Agric Food Chem. 56 (13):5422–542.
3 Wang, L., et al. (2008). The decapeptide CMS001 enhances swimming endurance in mice. Peptides. 29:1176-82.
4 Favano, A., et al. (2008). Peptide glutamine supplementation for tolerance of intermittent exercise in soccer players. Clinics. 63:27-32.
5 Jang, E.H., et al. (2008). Novel black soy peptides with antiobesity effects: Activation of leptin-like signaling and AMP-activated protein kinase. Int J Obes. 32(7):1161-70.