Human milk and infant formula modulate the intestinal microbiota and immune systems of human microbiota-associated mice.

Many infants on an exclusive breastfeeding regimen are often fed inadequate amounts, and this creates an imbalance between the overall effects of breast milk and commercial infant formulas. We comparatively analyzed the impact of human milk and two infant formulas in modulating the intestinal microbiota and the immune systems of mice colonized by healthy infant feces. The results showed that compared to infant formula, human milk decreased the levels of alanine transaminase, alkaline phosphatase, and total protein. Also, it improved the immune system through the level of cytokines (CD4+ lymphocytes, Th1, Th2, Th17, and Treg cells) and immunity indicators (IL-2, IL-4, IL-9, and sIgA). Human milk decreased intestinal mucosal permeability compared to infant formula. Bacterial 16S rRNA gene sequence analysis revealed that human milk increased the abundance of Akkermansia and Bacteroides, while infant formula increased the abundance of Lactobacillus and Escherichia_Shigella. Collectively, our results showed that human milk is more suitable for infants than the two commercial infant formulas based on intestinal microbiota and immune system analyses. These findings thus support a theoretical basis for the development of infant formulas.