Identification and comparison of bioactive peptides released from human milk vs. bovine milk-based test products across in vitro infant digestion

Background & Aims: Human milk (HM) is the preferred nutrition source for the developing infant; however, it is not always available and in many cases bovine milk-derived infant formula is fed. Though commercial infant formulas have been clinically proven to provide adequate nutrition compared with HM, the extent to which their digestion products, including bioactive peptides, remains understudied. The purpose of this study was to observe the differences between the release of bioactive peptides from HM and bovine milk-based test products (BMBTP) similar to infant formula across in vitro digestion. Methods: Two BMBTPs and HM from 4 donors were collected and digested using a static in vitro digestion designed to simulate term infants. Peptides were extracted from undigested feeds, gastric samples and intestinal samples and identified using LC-MS/MS and Proteome Discoverer. Identified peptides were examined for ≥80% homology with known bioactive peptides in the Milk Bioactive Peptide Database (MBPDB). Peptide numbers, relative abundances and functions were compared between HM and BMBTP across digestion. Results: BMBTPs produced different peptide profiles compared to HM samples; however, both sources shared many bioactive peptide functional groups, as well as three matched bioactive peptides. BMBTPs yielded higher bioactive peptide counts across all stages: 262 vs. 70 (undigested), 383 vs. 99 (gastric), and 267 vs. 31 (intestinal) stages. Though HM resulted in higher bioactive summed abundances in the undigested samples (1.6 x 108 in HM vs. 6.9 x 107 in BMBTPs) and the gastric phase (9.8 x 109 in HM vs. 4.3 x 109), BMBTPs produced greater summed abundance in the intestinal phase (1.9 x1010 in BMPTP vs. 7.5 x 108 in HM). HM had higher number and abundance of peptides with cellular growth functions, reaching an abundance of 1.6 x108 in the intestinal phase vs. 1.3 x 106 for BMBTPs. Additionally, BMBTPs exclusively produced peptides in 11 functional categories that were absent in HM across all digestive phases. Conclusions: These outcomes will provide insights on the extent to which BMBTPs reproduce the bioactive potential of HM in the infant gastrointestinal tract, which can guide developments in infant formula composition to better match the functionality of HM.