Endogenous proteins in terminal ileal digesta of adult subjects fed a casein-based diet

High-protein diet modifies colonic microbiota and luminal environment but not colonocyte metabolism in the rat model: the increased luminal bulk connection

“…In fact, such diets have been shown to increase satiety, to modify lipid metabolism, and to facilitate short-and middle-term weight reduction (24,61,72). However, the consequences on gut microbiota composition, on microbial-derived metabolites in the large intestine luminal content, and on colonocyte epithelial cell metabolic capacities have been little studied.Increasing protein intake induces an increase in the proportion of nitrogenous compounds, mainly protein, peptides, and to a lesser extent amino acids, entering the large intestine (13,23,25,51,64). They are subjected to luminal proteolysis and subsequent metabolism by the large number of microorganisms of the large intestine microbiota (about 10 11 to 10 12 viable bacteria/g content) (29) leading to the production of numerous amino acid-derived metabolites (53), including phenols, indoles, amines, sulfide, ammonia, and monocarboxylic acids.…”

“…Increasing protein intake induces an increase in the proportion of nitrogenous compounds, mainly protein, peptides, and to a lesser extent amino acids, entering the large intestine (13,23,25,51,64). They are subjected to luminal proteolysis and subsequent metabolism by the large number of microorganisms of the large intestine microbiota (about 10 11 to 10 12 viable bacteria/g content) (29) leading to the production of numerous amino acid-derived metabolites (53), including phenols, indoles, amines, sulfide, ammonia, and monocarboxylic acids.…”

Dietary Protein Structure Affects Endogenous Ileal Amino Acids But Not True Ileal Amino Acid Digestibility in Growing Male Rats

“…Nondietary protein found as part of the digesta at the terminal ileum comprises endogenous proteins secreted into the gut lumen, sloughed gut epithelial cells, and microbial bodies (1)(2)(3)(4). This flow of material, often collectively referred to as the endogenous protein flow, is of fundamental interest because it reflects gut metabolism and is a measure used to adjust apparent estimates of ileal protein and amino acid digestibility.…”

Food-derived bioactive peptides – a new paradigm

“…In addition, a significant microbial population inhabits parts of the human digestive tract, and as such bacterial cells die and are lysed, they also offer a supply of proteins to the gut lumen. Characterisation of endogenous proteins present in the lumen of the small intestine of the adult human after ingesting a casein-based meal has recently been made (32) . A new paradigm is proposed whereby it is hypothesised that the gut endogenous proteins provide a consistent supply of protein to the digestive lumen, which upon digestion give a consistent supply of bioactive peptides that act to complement and buffer the less consistent supply of bioactive peptides from food proteins.…”

“…The model diet comprised of milk, wheat, soya, egg and meat and the bioactive peptides present, post-digestion, were predicted for the major proteins present in these foods. Similarly, bioactive peptides present in the gut, postdigestion, were also predicted based on the reported composition of gut endogenous proteins and the reported digestibility of these proteins (32) . It was estimated that a total of 2563 mg of bioactive peptides per d would be generated from dietary proteins, while 5396 mg of bioactive peptides per d would be generated from gut endogenous proteins.…”