Human milk cream alters intestinal microbiome of preterm infants: a prospective cohort study

Background In very low birth weight (VLBW) infants, human milk cream added to standard human milk fortification is used to improve growth. This study aimed to evaluate the impact of cream supplement on the intestinal microbiome of VLBW infants. Methods Whole genome shotgun sequencing was performed on stool ( n = 57) collected from a cohort of 23 infants weighing 500-1250 grams (control = 12, cream = 11). Both groups received an exclusive human milk diet (mother’s own milk, donor human milk, and donor human milk-derived fortifier) with the cream group receiving an additional 2 kcal/oz cream at 100 mL/kg/day of fortified feeds and then 4 kcal/oz if poor growth. Results While there were no significant differences in alpha diversity, infants receiving cream significantly differed from infants in the control group in beta diversity. Cream group samples had significantly higher prevalence of Proteobacteria and significantly lower Firmicutes compared to control group. Klebsiella species dominated the microbiota of cream-exposed infants, along with bacterial pathways involved in lipid metabolism and metabolism of cofactors and amino acids. Conclusions Cream supplementation significantly altered composition of the intestinal microbiome of VLBW infants to favor increased prevalence of Proteobacteria and functional gene content associated with these bacteria. Impact We report changes to the intestinal microbiome associated with administration of human milk cream; a novel supplement used to improve growth rates of preterm very low birth weight infants. Since little is known about the impact of cream on intestinal microbiota composition of very low birth weight infants, our study provides valuable insight on the effects of diet on the microbiome of this population. Dietary supplements administered to preterm infants in neonatal intensive care units have the potential to influence the intestinal microbiome composition which may affect overall health status of the infant.