As soon as a child is born, his or her microbiome is continually being shaped by external factors such as diet and bacterial exposure. The first few years of life are critical in microbiome development as these early years will shape the composition of bacteria that will inhabit that individual’s body for years to come. Infant dietary habits play a critical role in this development. Breast milk has high nutritional content and is important in passing immunological factors from mother to child, as well as nutrients that are essential for gut colonization by bacteria. A team of scientists led by a group at University of North Carolina School of Medicine published in Frontiers in Cellular and Infection Microbiology on early changes and development of the microbiome in infants with different feeding and daycare habits.
Stool samples were collected from nine infants, some of which were exclusively breastfed (EBF) and some of which were non-exclusively breastfed (non-EBF). The infants were followed over a period of time from 2 weeks to 14 months, and samples were collected before and after the introduction of solid foods. The samples were tested for differences in bacterial composition.
The scientists found that infants that were solely breastfed and did not receive formula had guts that were more prepared for the introduction of solid foods. When solid foods were introduced to their diets, the microbial shift was much less dramatic than the shift for infants who were breastfed while also receiving formula.
Analysis showed that non-EBF infants had greater microbiome species diversities compared to EBF infants. Also, non-EBF infants showed lower abundances of Bifidobacterium and greater abundances of Eggerthella compared to EBF infants. Bifidobacterium is a bacterium that is associated with good digestion. After introduction of solid foods, however, EBF infants showed an increase in Eggerthella abundance, and non-EBF infants showed an increase in Bifidobacterium abundance.
In a second part of the study, researchers considered day care attendance when comparing the microbiome of the infants. They found that attending daycare resulted in a more diverse microbiome, but feeding habits were the most important factor for microbiome composition after the introduction of solid foods.
It is clear from this study, in addition to others we have discussed, that there are many factors contributing to microbiome diversity and species richness. This study highlights the important role that diet plays on early microbiome development. What was quite interesting was that while many studies often equate a more diverse microbiome with health, the infants that were exclusively breastfed had less diverse microbiomes yet they were more prepared for the introduction of solid foods. This study only included nine participants and should be expanded to include a greater number of infants to better understand this relationship, but it can still help inform the conversation around breastfeeding versus formula feeding.