Stool microbiome, pH and short/branched chain fatty acids in infants receiving extensively hydrolyzed formula, amino acid formula, or human milk through two months of age

Abstract

Background Early infant feeding with intact or extensively hydrolyzed (EH) proteins or free amino acids (AA) may differentially affect intestinal microbiota composition and immune reactivity. This multicenter, double-blind, controlled, parallel-group, pilot study compared stool microbiota from Baseline (1–7 days of age) up to 60 days of age in healthy term infants who received mother’s own milk (assigned to human milk [HM] reference group) (n = 25) or were randomized to receive one of two infant formulas: AA-based (AAF; n = 25) or EH cow’s milk protein (EHF; n = 28). Stool samples were collected (Baseline, Day 30, Day 60) and 16S rRNA genes were sequenced. Alpha (Shannon, Simpson, Chao1) and beta diversity (Bray Curtis) were analyzed. Relative taxonomic enrichment and fold changes were analyzed (Wilcoxon, DESEq2). Short/branched chain fatty acids (S/BCFA) were quantified by gas chromatography. Mean S/BCFA and pH were analyzed (repeated measures ANOVA). Results At baseline, alpha diversity measures were similar among all groups; however, both study formula groups were significantly higher versus the HM group by Day 60. Significant group differences in beta diversity at Day 60 were also detected, and study formula groups were compositionally more similar compared to HM. The relative abundance of Bifidobacterium increased over time and was significantly enriched at Day 60 in the HM group. In contrast, a significant increase in members of Firmicutes for study formula groups were detected at Day 60 along with butyrate-producing species in the EHF group. Stool pH was significantly higher in the AAF group at Days 30 and 60. Butyrate increased significantly from Baseline to Day 60 in the EHF group and was significantly higher in study formula groups vs HM at Day 60. Propionate was also significantly higher for EHF and AAF at Day 30 and AAF at Day 60 vs HM. Total and individual BCFA were higher for AAF and EHF groups vs HM through Day 60. Conclusions Distinct patterns of early neonatal microbiome, pH, and microbial metabolites were demonstrated for infants receiving mother’s own milk compared to AA-based or extensively hydrolyzed protein formula. Providing different sources of dietary protein early in life may influence gut microbiota and metabolites. Trial registration ClinicalTrials.gov Identifier: NCT02500563. Registered July 28, 2015.

Longitudinal Profiles of Dietary and Microbial Metabolites in Formula- and Breastfed Infants

“…Several studies consistently showed that children fed with breast milk or formula have a clear and distinct fecal metabolome, as recently summarized by Laurens et al (Laurens et al, 2020). Targeted or non-targeted profiling of infant stool resulted in the detection of various metabolite classes including short chain fatty acids (SCFAs), amino acids, amino acid catabolites, fatty acids, human milk oligosaccharides, monosaccharides, purine degradation products or even plantbased metabolites from soy-based formula (Chow et al, 2014;Martin et al, 2014;Dotz et al, 2015;Dotz et al, 2016;Martin et al, 2016b;Bridgman et al, 2017;He et al, 2019;Brink et al, 2020;Kok et al, 2020;Li et al, 2020).…”

Impact of Extensively Hydrolyzed Infant Formula on Circulating Lipids During Early Life

“…Interestingly, our observations show that gut microbiome composition differed between the infants fed HF as compared to RF-fed infants. Recent studies also indicate that hydrolyzed milk protein has a modest effect on the gut microbiome composition ( 51 , 52 ). Taken together, it is plausible that different dietary protein sources in early life may influence gut microbiotal composition and circulating lipids; however, the underlying mechanisms remain unclear.…”

Free threonine in human breast milk is related to infant intestinal microbiota composition

“…Only few data are available that address a possible relationship between maternal serum and breast milk FAA (Ramírez et al 2001 ), providing results that may indicate underlying mechanisms for the emergence of these different FAA patterns in breast milk. Furthermore, hardly any study addressed the FAA composition of breast milk in lactation in relation to the infants’ intestinal microbiota (He et al 2020 ; Kok et al 2020 ).…”

“…Provision of different sources and amounts of dietary protein was already shown to influence gut microbiota and its metabolites, e.g. when comparing breast-fed with formula-fed infants (Kok et al 2020 ). However, there is only limited data on how the different FAA in human milk relate to or even influence the composition of the infant's microbiota.…”