The Gut Microbiota Differ in Exclusively Breastfed and Formula-Fed United States Infants and are Associated with Growth Status

J Nutr. 2023 Sep;153(9):2612-2621. doi: 10.1016/j.tjnut.2023.07.009. Epub 2023 Jul 26.

Abstract

Background: Evidence regarding the effects of infant feeding type (exclusive breastfeeding compared with exclusive formula feeding) on the gut microbiota and how it impacts infant growth status is limited.

Objectives: The primary objective was to compare gut microbiota by feeding type and characterize the associations between gut microbiota and infant growth status.

Methods: Stool samples from healthy, full-term infants (4-5 mo-old) who were either exclusively breastfed (BF) or exclusively formula-fed (FF) in Denver, CO, United States were collected, and fecal 16S ribosomal ribonucleic acid gene-based profiling was conducted. Length and weight were measured at the time of stool collection. Length-for-age z-score, weight-for-age z-scores (WAZ), and weight-for-length z-scores were calculated based on the World Health Organization standards. Associations between gut microbial taxa and anthropometric z-scores were assessed by Spearman's rank correlation test.

Results: A total of 115 infants (BF n = 54; FF n = 61) were included in this study. Feeding type (BF compared with FF) was the most significant tested variable on gut microbiota composition (P < 1 × 10-⁶), followed by mode of delivery and race. Significant differences were observed in α-diversity, β-diversity, and relative abundances of individual taxa between BF and FF. BF infants had lower α-diversity than FF infants. Abundances of Bifidobacterium and Lactobacillus were greater in the breastfeeding group. FF infants had a higher relative abundance of unclassified Ruminococcaceae (P < 0.001), which was associated with a higher WAZ (P < 0.001) and length-for-age z-score (P < 0.01). Lactobacillus was inversely associated with WAZ (P < 0.05).

Conclusions: Feeding type is the main driver of gut microbiota differences in young infants. The gut microbiota differences based on feeding type (exclusive breast- or formula feeding) were associated with observed differences in growth status. This trial was registered at clinicaltrials.gov as NCT02142647, NCT01693406, and NCT04137445.

Keywords: breastfeeding; growth status; gut microbiota; infant formula; mode of feeding.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Breast Feeding*
  • Feces / microbiology
  • Female
  • Gastrointestinal Microbiome*
  • Humans
  • Infant
  • Infant Formula
  • Infant Nutritional Physiological Phenomena
  • Milk, Human

Associated data

  • ClinicalTrials.gov/NCT04137445
  • ClinicalTrials.gov/NCT02142647
  • ClinicalTrials.gov/NCT01693406