In Vitro Fermentation of Animal and Plant Protein Isolates by the Human Gut Microbiota Under High and Low Carbohydrate Conditions

• Published in: Molecular nutrition & food research 2024-07, Vol.68 (14), p.e2300555-n/a
• Main Authors: Behounek, Marissa, Cochran, Darcy, Motta‐Romero, Hollman A., Yang, Qinnan, Ding, Wensheng, Morton, Martha, Majumder, Kaustav, Powers, Robert, Rose, Devin J.
• Format: Article
• Language: English
• Subjects: Adult; Amino acid composition; Amino acids; Amino Acids - metabolism; Ammonia; Animals; butyrate; Carbohydrates; Chain branching; Dietary Carbohydrates - metabolism; dietary fiber; Dietary Proteins - metabolism; Digestive system; Fecal microflora; Feces - microbiology; Female; Fermentation; Gastrointestinal Microbiome - drug effects; Gastrointestinal Microbiome - physiology; Gastrointestinal tract; Humans; Intestinal microflora; Male; Metabolites; Microbiomes; Microbiota; Microorganisms; milk; Peptides; Protein composition; Proteins; Proteolysis; soy
• ISSN: 1613-4125; 1613-4133; 1613-4133
• DOI: 10.1002/mnfr.202300555

Scope There is a lack of research comparing how different protein isolates influence the microbiome, especially when carbohydrate (CHO) availability is varied. The objective is to determine changes in gut microbiota composition and function during fermentation of digested protein isolates under high and low CHO conditions. Methods and results Protein isolates from beef, egg white, milk, pea, and soy are subjected to in vitro digestion and fermentation with human fecal microbiota. Under low CHO conditions, the microbiota is primarily proteolytic with decreased concentrations of peptides and increased variance among microbial taxa and production of ammonia and branched chain fatty acids by the microbiota. Milk protein not only results in the highest production of butyrate and p‐hydroxyphenylacetate but also has high concentrations of deleterious fermentation metabolites. Amino acid composition of the protein isolates is significantly correlated with abundances of many microbial taxa and metabolites, but the correlations are stronger in the low CHO medium. Conclusion This study shows that low CHO conditions increase proteolytic fermentation and result in increased differences in microbiota response to protein isolates. It also showed that amino acid composition is highly associated with microbiota composition and function especially under low CHO conditions. High‐protein, low‐fiber diets are common, yet little is known about the effects of different proteins on the human gut microbiome. Varying amino acid compositions, molecular weights, and other unique properties of protein isolates induces exaggerated differential effect on microbiome composition and function under low versus high carbohydrate conditions. This suggests that under high‐protein, low‐fiber diets, the microbiome may be more influenced by protein than dietary fiber.