Amino Acid and Peptide Absorption and Transport across the Intestine

Energy metabolism in the digestive tract and liver of cattle: influence of physiological state and nutrition

“…Net liver removal can account maximally for 70 to 80 % of urea N released (Huntington and Eisemann, 1988;Reynolds et al, 1988;Huntington, 1989). The capacity of a healthy liver to remove ammonia is not exceeded with normal diets (Symonds et aI, 1981;Orzechowski et al, 1987) (Webb, 1986 (Huntington et al, 1988). This may explain in part some of the metabolism behind greater efficiency of energy use by ruminants fed legumes compared to grasses (Rattray and Joyce, 1970;Tyrrell et al, 1982;Thompson et al, 1985;Varga et al, 1987 …”

Physiology, regulation and multifunctional activity of the gut wall: a rationale for multicompartmental modelling

“…Small peptides as well as free AA may be transported into cells (Webb & Bergman, 1991), but probably the main part of these peptides is hydrolysed by the GIW and enters metabolism or appears in portal blood as free AA. The dietary source of digestible protein influences the kinetics of protein digestion and AA absorption, and thereby the type and the quantity of AA appearing in portal blood.…”

“…Other AA are involved in the synthesis of nucleic acids and peptides such as glutathione that stimulates gluconeogenesis in the liver (Klasing & Calvert, 1999). Finally, the availability of preformed monomers of macromolecules such as DNA, RNA and fats may also affect nutrient utilisation by enterocytes and immune cells (Bueno et al 1994;Waheed et al 1998;Webb & Bergman, 1991) during immune activation.…”

Nutritional and health benefits of semi-elemental diets: A comprehensive summary of the literature

“…Previously, the authors reported that intrahepatic levels of cysteine, adenosine and optimum digestive process ultimately leading to an absorptive advantage compared with free amino acid and intact protein based formulas. Indeed, several studies have suggested that the majority of nitrogen from protein is absorbed as peptides and that amino acids may be absorbed more efficiently in the form of peptides than free amino acids [49][50][51] . Amino acids infused into the intestine in peptide form are more readily absorbed than free amino acids, secondary to the PepT1 transporter system.…”