How Milk Proteins Break Down During Digestion and Which Bioactive Peptides Survive to Be Absorbed
Including intestinal brush border enzymes in digestion simulations better predicts which milk-derived peptides survive digestion, and the structure of peptide ends determines how well they're absorbed through the intestinal wall.
Quick Facts
What This Study Found
Adding brush border membrane (BBM) enzymes to the standard INFOGEST digestion protocol revealed additional peptide cleavage sites beyond pancreatic digestion alone. BBM enzymes (amino- and carboxy-peptidases) reduced total peptide numbers but increased free amino acid concentrations, better approximating real digestion.
Comparing the in vitro peptidome with peptides from actual human jejunal aspirates, BBM addition allowed identification of peptides found in vivo — though neither model reproduced the full peptide diversity seen in human digestion. For six beta-casein peptides including beta-casomorphin-7, transepithelial transport through Caco-2 cells showed that N- and C-terminal residue identity was a key determinant of absorption rate.
Key Numbers
How They Did This
Casein and whey proteins were digested using the standardized INFOGEST protocol with and without brush border membrane enzymes. Resulting peptides were analyzed by tandem mass spectrometry. The in vitro peptidome was compared with peptides previously identified in human jejunal aspirates after milk protein ingestion. Transepithelial transport of six beta-casein peptides was evaluated using Caco-2 cell monolayers (a standard model of intestinal absorption).
Why This Research Matters
Understanding which bioactive peptides survive digestion and get absorbed is critical for developing functional foods and nutraceuticals. This study improves the standard lab simulation of digestion, making it more predictive of what actually happens in the human gut. The finding that peptide end structure determines absorption rate provides practical guidance for designing peptides with better bioavailability.
The Bigger Picture
Food-derived bioactive peptides are a growing area of interest for health applications, but a major gap has been understanding which peptides actually survive digestion and reach the bloodstream. This study advances the methodology for predicting bioactive peptide bioavailability, which is essential for the entire field — from dairy-derived opioid peptides to antihypertensive sequences to immunomodulatory peptides found in various protein sources.
What This Study Doesn't Tell Us
The in vitro digestion model, even with BBM enzymes, could not reproduce the full diversity of peptides found in human intestinal fluid, suggesting additional factors are involved in vivo. Caco-2 cells are a simplified model of intestinal absorption that may not fully capture in vivo transport complexity. Only six beta-casein peptides were tested for transport. The study did not assess biological activity of the absorbed peptides.
Questions This Raises
- ?What additional factors in the human gut (microbiome, mucus layer, immune interactions) contribute to the peptide diversity not captured by in vitro models?
- ?Could the terminal residue findings be used to engineer food-derived peptides with improved intestinal absorption?
- ?Does beta-casomorphin-7 cross the intestinal barrier in sufficient quantities to exert opioid-like effects in humans?
Trust & Context
- Key Stat:
- Terminal residues control absorption The N- and C-terminal amino acids of milk-derived peptides determined how quickly they crossed the intestinal wall in transport studies, providing a design rule for improving peptide bioavailability.
- Evidence Grade:
- This is a methodological in vitro study that improves digestion simulation protocols and includes validation against human intestinal aspirate data. While rigorous in its approach, all absorption data come from Caco-2 cell models rather than human studies.
- Study Age:
- Published in 2022, this study uses the current INFOGEST standardized digestion protocol and provides timely methodological improvements for the growing field of food-derived bioactive peptides.
- Original Title:
- In vitro digestion of milk proteins including intestinal brush border membrane peptidases. Transepithelial transport of resistant casein domains.
- Published In:
- Food research international (Ottawa, Ont.), 157, 111238 (2022)
- Authors:
- Vivanco-Maroto, Santiaga María, Santos-Hernández, Marta, Sanchón, Javier, Picariello, Gianluca, Recio, Isidra, Miralles, Beatriz
- Database ID:
- RPEP-06567
Evidence Hierarchy
Frequently Asked Questions
Do bioactive peptides from milk survive digestion?
Some do. This study showed that certain casein-derived peptides, including beta-casomorphin-7, resist breakdown during digestion and can cross the intestinal wall. However, the full range of surviving peptides is more diverse in actual human digestion than current lab simulations can predict.
Why does it matter how peptides are structured at their ends?
The amino acids at the beginning and end of a peptide (N- and C-terminal residues) determine how efficiently it crosses the intestinal wall into the bloodstream. This finding could help scientists design food-derived peptides that are better absorbed, making functional foods more effective.
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Cite This Study
https://rethinkpeptides.com/research/RPEP-06567APA
Vivanco-Maroto, Santiaga María; Santos-Hernández, Marta; Sanchón, Javier; Picariello, Gianluca; Recio, Isidra; Miralles, Beatriz. (2022). In vitro digestion of milk proteins including intestinal brush border membrane peptidases. Transepithelial transport of resistant casein domains.. Food research international (Ottawa, Ont.), 157, 111238. https://doi.org/10.1016/j.foodres.2022.111238
MLA
Vivanco-Maroto, Santiaga María, et al. "In vitro digestion of milk proteins including intestinal brush border membrane peptidases. Transepithelial transport of resistant casein domains.." Food research international (Ottawa, 2022. https://doi.org/10.1016/j.foodres.2022.111238
RethinkPeptides
RethinkPeptides Research Database. "In vitro digestion of milk proteins including intestinal bru..." RPEP-06567. Retrieved from https://rethinkpeptides.com/research/vivanco-maroto-2022-in-vitro-digestion-of
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.