Influence of breast milk intake on the acquisition of the intestinal microbiome in premature infants - Breastfeeding

Background

The initial acquisition and early development of the gut microbiome during infancy are important for human health throughout life. The mode of birth, administration of antibiotics, care environment, and nutrition have all been shown to play a role in the assembly of the gut microbiome during the first years of life.

In premature infants, who have a disproportionately high risk of developing inflammatory intestinal diseases (i.e., necrotizing enterocolitis), a unique set of clinical factors influences the establishment of the microbiome. The purpose of this study was to determine the influence of nutritional exposures on the gut microbiome in a cohort of premature infants during the early stages of life.

Results

A principal component analysis of 199 samples from 30 premature infants (<32 weeks) during the first 60 days after birth showed that the gut microbiome was influenced by postnatal time (p < 0.001, R² = 0.13), birth weight (p < 0.001, R² = 0.08), and nutrition (p < 0.001, R² = 0.21).

Infants who were fed breast milk had greater initial bacterial diversity and a more gradual acquisition of diversity compared with infants who were fed infant formula.

The microbiome of breastfed infants was more similar regardless of birth weight (p = 0.049), in contrast to the microbiome of formula-fed infants, which clustered differently according to birth weight (p < 0.001).

After adjusting for differences in intestinal maturity, an ordered succession of microbial phylotypes was observed in breastfed infants, which appeared to be disrupted in formula-fed infants.

Supplementation with pasteurized donor human milk showed partial success in promoting a microbiome more similar to that of breastfed infants and in moderating rapid increases in bacterial diversity.

Conclusions

The gut microbiome of premature infants is influenced by postnatal time, birth weight, gestational age, and nutrition.

Breast milk feeding appears to mask the influence of birth weight, suggesting a protective effect against intestinal immaturity in premature infants.

These findings suggest not only a microbial mechanism underlying the body of evidence showing that breast milk promotes intestinal health in premature infants, but also a dynamic interaction between host factors and diet that facilitates the colonization and enrichment of specific microbes during the establishment of the premature infant microbiota.