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Research Project: Molecular, Cellular, and Regulatory Aspects of Nutrition During Development

Location: Children's Nutrition Research Center

Title: Postprandial amino acid kinetics of milk protein mixtures are affected by composition, but not denaturation, in neonatal piglets

item WELCH-JERNIGAN, R - Baylor College Of Medicine
item ABRAHAMSE, E - Utrecht University
item STOLL, B - Baylor College Of Medicine
item SMITH, O - Baylor College Of Medicine
item WIERENGA, P - Wageningen University
item VAN DE HEIJNING, BJM - Utrecht University
item RENES, IB - Utrecht University
item Burrin, Douglas - Doug

Submitted to: Current Developments in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2018
Publication Date: 12/19/2018
Citation: Welch-Jernigan, R.J., Abrahamse, E., Stoll, B., Smith, O., Wierenga, P.A., Van De Heijning, B., Renes, I., Burrin, D.G. 2018. Postprandial amino acid kinetics of milk protein mixtures are affected by composition, but not denaturation, in neonatal piglets. Current Developments in Nutrition. 3(4):1-11.

Interpretive Summary: The protein content of human breast milk is lower than most commercially available infant formulas. This higher protein content in infant formulas has been suggested to lead to higher obesity in later life. The higher weight gain and body fat mass in formula-fed infants in later life has been linked to increase absorption of select amino acids, the branched chain amino acids, and higher blood insulin levels. These differences in amino acid absorption are thought to be related to differences in the type of protein contained in breast milk and infant formula and how it is processed during formula manufacture. The goal of the current study was to test whether an alternative processing method and mixture of milk proteins would result in differences in intestinal absorption and blood levels of amino acids and insulin. Our results showed that changes in the amino acid content of the milk proteins included in the diet, and not the process of denaturation, has a more important influence and the absorption and blood levels of most amino acids, including the branched chain amino acids. The protein based ingredient tested lead to higher blood levels of branched chain amino acids but a lower spike in blood insulin after feeding

Technical Abstract: Multiple studies have indicated that formula-fed infants show a different growth trajectory compared to breast-fed infants. The observed growth rates are suggested to be linked to higher postprandial levels of branched chain amino acids (BCAA) and insulin related to differences in protein quality. We evaluated the effects of milk protein denaturation and milk protein composition on postprandial plasma and hormone concentrations. Neonatal piglets were bolus fed randomly in an incomplete cross-over design two of three milk protein solutions: native whey protein isolate (NWPI), denatured whey protein isolate (DWPI), or protein base ingredient, comprising whey and casein (PBI). Post-prandial plasma amino acids (AA), insulin, GLP-1, glucose, and paracetamol concentrations were assayed. Plasma responses were fitted with a model of first order absorption with linear elimination. DWPI (91% denatured protein) vs NWPI (91% native protein) showed lower essential AA (EAA) (~10%) and BCAA (13–19%) concentrations in the first 30–60 min. However, total AA (TAA) concentration per time-point and 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 NWPI. The TAA rate constant for absorption (ka) was twofold higher in PBI than NWPI. Plasma BCAA levels from 60 to 180 min and AUC were higher in PBI vs. NWPI. Plasma EAA concentrations and AUCs in PBI and NWPI were not different. 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 the modifying protein composition, but not denaturation, of milk protein solutions impacts the postprandial amino acid availability in neonatal piglets