Ileal Digestibility of Nitrogen and Amino Acids in Human Milk and an Infant Formula as Determined in Neonatal Minipiglets

Elise Charton; Gwénaële Henry; Armelle Cahu; Yann Le Gouar; Patrice Dahirel; Paul J Moughan; Carlos A Montoya; Amandine Bellanger; Didier Dupont; Isabelle Le Huërou-Luron; Amélie Deglaire

doi:10.1016/j.tjnut.2023.02.025

Ileal Digestibility of Nitrogen and Amino Acids in Human Milk and an Infant Formula as Determined in Neonatal Minipiglets

J Nutr. 2023 Apr;153(4):1063-1074. doi: 10.1016/j.tjnut.2023.02.025. Epub 2023 Mar 2.

Affiliations

¹ STLO, Institut Agro, INRAE, Rennes, France; Institut NuMeCan, INRAE, INSERM, Univ Rennes, Saint Gilles, France.
² STLO, Institut Agro, INRAE, Rennes, France.
³ Institut NuMeCan, INRAE, INSERM, Univ Rennes, Saint Gilles, France.
⁴ Riddet Institute, Massey University, Palmerston North, New Zealand.
⁵ Riddet Institute, Massey University, Palmerston North, New Zealand; Smart Foods Innovation and Bioproducts, AgResearch Limited, Palmerston North, New Zealand.
⁶ CHU Rennes, Pediatrics Department, CIC-Inserm 1414, Rennes, France.
⁷ STLO, Institut Agro, INRAE, Rennes, France. Electronic address: amelie.deglaire@institut-agro.fr.

PMID: 36868512
DOI: 10.1016/j.tjnut.2023.02.025

Abstract

Background: Infant formula (IF) has to provide at least the same amount of amino acids (AAs) as human milk (HM). AA digestibility in HM and IF was not studied extensively, with no data available for tryptophan digestibility.

Objectives: The present study aimed to measure the true ileal digestibility (TID) of total nitrogen and AAs in HM and IF to estimate AA bioavailability using Yucatan mini-piglets as an infant model.

Methods: Twenty-four 19-day-old piglets (males and females) received either HM or IF for 6 days or a protein-free diet for 3 days, with cobalt-EDTA as an indigestible marker. Diets were fed hourly over 6 h before euthanasia and digesta collection. Total N, AA, and marker contents in diets and digesta were measured to determine the TID. Unidimensional statistical analyses were conducted.

Results: Dietary N content was not different between HM and IF, while true protein was lower in HM (-4 g/L) due to a 7-fold higher non-protein N content in HM. The TID of total N was lower (P < 0.001) for HM (91.3 ± 1.24%) than for IF (98.0 ± 0.810%), while the TID of amino acid nitrogen (AAN) was not different (average of 97.4 ± 0.655%, P = 0.272). HM and IF had similar (P > 0.05) TID for most of the AAs including tryptophan (96.7 ± 0.950%, P = 0.079), except for some AAs (lysine, phenylalanine, threonine, valine, alanine, proline, and serine), with small significant difference (P < 0.05). The first limiting AA was the aromatic AAs, and the digestible indispensable AA score (DIAAS) was higher for HM (DIAAS_HM = 101) than for IF (DIAAS_IF = 83).

Conclusion: HM, compared to IF, had a lower TID for total N only, whereas the TID of AAN and most AAs, including Trp, was high and similar. A larger proportion of non-protein N is transferred to the microbiota with HM, which is of physiological relevance, although this fraction is poorly considered for IF manufacturing.

Keywords: bioavailability; digestible indispensable AA score; human milk; infant nutrition; multiple hydrolysis; true digestibility; tryptophan.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acids* / metabolism
Animal Feed / analysis
Animals
Diet
Diet, Protein-Restricted
Digestion / physiology
Female
Humans
Ileum / metabolism
Infant
Infant Formula / chemistry
Infant, Newborn
Male
Milk, Human* / chemistry
Nitrogen / metabolism
Swine
Tryptophan / metabolism

Substances

Amino Acids
Tryptophan
Nitrogen