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The postprandial plasma essential amino acid (AA) peak concentrations of infant formula (IF) are higher than those of human milk (HM) in infants. In addition, several HM proteins have been recovered intact in infant stool and appeared digestion resistant in vitro. We, therefore, hypothesized that gastrointestinal protein hydrolysis of IF is faster than HM and leads to accelerated absorbable digestion product release. HM and IF protein hydrolysis kinetics were compared in a two-step semi-dynamic in vitro infant digestion model, and the time course of degree of protein hydrolysis (DH), loss of intact protein, and release of free AA and peptides was evaluated. Gastric DH increase was similar for IF and HM, but the rate of intestinal DH increase was 1.6 times higher for IF than HM. Intact protein loss in IF was higher than HM from 120 min gastric phase until 60 min intestinal phase. Intestinal phase total digestion product (free AA + peptides <5 kDa) concentrations increased ~2.5 times faster in IF than HM. IF gastrointestinal protein hydrolysis and absorbable product release are faster than HM, possibly due to the presence of digestion-resistant proteins in HM. This might present an opportunity to further improve IF bringing it closer to HM. [ABSTRACT FROM AUTHOR]

Background. The human digestive tract is structurally mature at birth, yet maturation of gut functions such as digestion and mucosal barrier continues for the next 1–2 years. Human milk and infant milk formulas (IMF) seem to impact maturation of these gut functions differently, which is at least partially related to high temperature processing of IMF causing loss of bioactive proteins and formation of advanced glycation end products (AGEs). Both loss of protein bioactivity and formation of AGEs depend on heating temperature and time. The aim of this study was to investigate the impact of mildly pasteurized whey protein concentrate (MP-WPC) compared to extensively heated WPC (EH-WPC) on gut maturation in a piglet model hypersensitive to enteral nutrition. Methods. WPC was obtained by cold filtration and mildly pasteurized (73 °C, 30 s) or extensively heat treated (73 °C, 30 s + 80 °C, 6 min). Preterm (~90% gestation) and near-term piglets (~96% gestation) received enteral nutrition based on MP-WPC or EH-WPC for five days. Macroscopic and histologic lesions in the gastro-intestinal tract were evaluated and intestinal responses were further assessed by RT-qPCR, immunohistochemistry and enzyme activity analysis. Results. A diet based on MP-WPC limited epithelial intestinal damage and improved colonic integrity compared to EH-WPC. MP-WPC dampened colonic IL1-β, IL-8 and TNF-α expression and lowered T-cell influx in both preterm and near-term piglets. Anti-microbial defense as measured by neutrophil influx in the colon was only observed in near-term piglets, correlated with histological damage and was reduced by MP-WPC. Moreover, MP-WPC stimulated iALP activity in the colonic epithelium and increased differentiation into enteroendocrine cells compared to EH-WPC. Conclusions. Compared to extensively heated WPC, a formula based on mildly pasteurized WPC limits gut inflammation and stimulates gut maturation in preterm and near-term piglets and might therefore also be beneficial for preterm and (near) term infants. [ABSTRACT FROM AUTHOR]

Background Multiple studies have indicated that formula-fed infants show a different growth trajectory compared with breastfed infants. The observed growth rates are suggested to be linked to higher postprandial levels of branched chain amino acids (BCAAs) and insulin related to differences in protein quality. Objective We evaluated the effects of milk protein denaturation and milk protein composition on postprandial plasma and hormone concentrations. Methods Neonatal piglets were bolus-fed randomly, in an incomplete crossover design, 2 of 3 milk protein solutions: native whey protein isolate (NWPI), denatured whey protein isolate (DWPI), or protein base ingredient, comprising whey and casein (PBI). Postprandial plasma amino acids (AAs), insulin, glucagon-like peptide 1, glucose, and paracetamol concentrations were assayed. Plasma responses were fitted with a model of first-order absorption with linear elimination. Results DWPI (91% denatured protein) compared with NWPI (91% native protein) showed lower essential amino acids (EAAs) (∼10%) and BCAA (13–19%) concentrations in the first 30–60 min. However, total amino acid (TAA) concentration per time-point and area under the curve (AUC), as well as EAA and BCAA AUC were not different. PBI induced a ∼30% lower postprandial insulin spike than NWPI, yet plasma TAA concentration at several time-points and AUC was higher in PBI than in NWPI. The TAA rate constant for absorption (k a) was twofold higher in PBI than in NWPI. Plasma BCAA levels from 60 to 180 min and AUC were higher in PBI than in NWPI. Plasma EAA concentrations and AUCs in PBI and NWPI were not different. Conclusions Denaturation of WPI had a minimal effect on postprandial plasma AA concentration. The differences between PBI and NWPI were partly explained by the difference in AA composition, but more likely differences in protein digestion and absorption kinetics. We conclude that modifying protein composition, but not denaturation, of milk protein solutions impacts the postprandial amino acid availability in neonatal piglets. [ABSTRACT FROM AUTHOR]