Development of Human Microbiota

The development of human microbiota begins at the time of birth.

Newborns get microbes from the mother. Vaginal delivery is associated with colonization by Bifidobacterium and Bacteroides, while cesarean delivery is linked to colonization by Staphylococcus and Corynebacterium.

In infants, breast milk promotes the growth of Bifidobacterium species by providing oligosaccharides that specifically serve as nutrients for these bacteria.

As the infant's diet transitions to include solid foods, microbial diversity increases, and adult-associated taxa such as Bacteroidota and Bacillota become more prominent.

By the age of three, the gut microbiota stabilizes into a more adult-like composition.

In adulthood, the gut microbiota remains relatively stable but varies greatly between individuals and is influenced by diet, lifestyle, and major life events.

With aging, microbial diversity often decreases, with a notable shift in the balance of Bacillota and Bacteroidota, and reduced levels of beneficial Bifidobacteria.

Maintaining a diverse, balanced gut microbiota supports metabolic health, immune function, and may influence longevity.