Survival of intact bovine whey proteins across in vivo and simulated static in vitro models of the adult gastrointestinal tract
While most whey proteins don't survive digestion intact, the few that do might be enough to provide health benefits. Understanding this process opens new possibilities for developing functional foods and therapeutic proteins that can survive the journey through our digestive system.
College of Health researcher(s)
College unit(s)
Highlights
- Intact protein and degradation patterns were compared via proteomics and SDS-PAGE.
- β-lactoglobulin survived intact at 1 % in vivo and 0.4 % in vitro digestion.
- In vitro and in vivo intestinal digesta had similar intact protein patterns.
Abstract
Bovine whey contains bioactive proteins that could benefit consumer health, but their intact bioactivity depends on their ability to survive the digestive process and remain intact to their sites of action. Our study assessed whey protein degradation in the adult human jejunum after whey protein isolate ingestion and during static in vitro gastric and intestinal digestions, using LC-MS/MS-based proteomics and SDS-PAGE. We found that 53 % of the protein counts identified in the gastric digesta, including β-lactoglobulin and lactoferrin were stable under simulated gastric conditions. However, most proteins were degraded during both in vitro and in vivo intestinal digestion. The intact protein survival profiles were closely aligned between in vitro and in vivo digestion samples. Understanding the survival of specific whey proteins during digestion will help determine their biological relevancy in their intact forms within the gastrointestinal tract and may inspire strategies to enhance their stability for specific functions.
Whey Protein Digestion FAQ
What is bovine whey and why is it important?
Bovine whey, a byproduct of cheese production, is a rich source of essential amino acids and bioactive proteins. These proteins exhibit various potential health benefits, including:
- Antimicrobial and antiviral properties: Inhibiting the growth and adhesion of harmful microorganisms.
- Anti-inflammatory and immunomodulatory effects: Supporting immune function and reducing inflammation.
- Anticancerogenic activity: Potentially suppressing the growth of cancer cells.
What happens to whey proteins during digestion?
Dietary proteins, including those from whey, undergo degradation throughout the digestive process. In the stomach, acidic pH and pepsin initiate protein breakdown. Subsequently, in the small intestine, pancreatic proteases like trypsin and chymotrypsin further digest proteins into smaller peptides and amino acids for absorption.
How does gastric digestion affect the stability of whey proteins?
Static in vitro gastric digestion, simulating stomach conditions, revealed that certain whey proteins exhibit resistance to degradation. Notably, β-lactoglobulin (BLG) remained largely intact, likely due to its tightly folded structure protecting susceptible peptide bonds from pepsin. Other proteins like α-lactalbumin (ALA) showed gradual degradation, while some minor proteins like lactoferrin (LF) and NPC2 displayed partial resistance.
What happens to whey proteins during intestinal digestion?
Intestinal digestion, simulated using the INFOGEST static model, resulted in extensive degradation of most whey proteins. SDS-PAGE analysis showed minimal intact protein bands. Proteomic analysis confirmed that the majority of whey proteins, including BLG and ALA, were nearly completely digested, although trace amounts were still detectable.
Are there any whey proteins that survive intestinal digestion?
While most whey proteins are extensively digested, some show slight resistance to intestinal enzymes. Bovine serum albumin (BSA) exhibited a relatively higher survival rate compared to others. Additionally, trace amounts of NPC2, LF, and PIGR remained detectable.
How does whey protein digestion in the human jejunum compare to in vitro models?
Proteomic analysis of jejunal fluid collected from adults after ingesting whey protein isolate (WPI) revealed a similar pattern of digestion observed in the in vitro model. BLG, although detected in the jejunum for at least an hour, showed low intact survival (around 1%), comparable to the in vitro results. This suggests that the static in vitro digestion model closely replicates the intestinal digestion process in humans.
What are the implications of the low intact survival of whey proteins?
Despite low intact survival, some whey proteins, like BLG, may still exert bioactivity within the gut. The estimated BLG concentration reaching the jejunum could be sufficient to exhibit antimicrobial effects. However, further research is needed to understand the potential health implications of whey protein digestion products.
How can the survival of whey proteins be improved?
The study suggests that heat treatments used in WPI processing might increase protein digestibility. Comparing the digestion of raw and processed whey proteins could provide insights into the impact of processing on protein stability. Additionally, encapsulation strategies might enhance the survival of bioactive whey proteins in the gastrointestinal tract.