Gut microbiota in early stages of life

1 June 2021 – 3 min read

Immediately after birth, the gut of new-borns is colonized by microbes, conforming a simple ecosystem. This group of microorganisms (known as gut microbiota) will change during a lifetime, having essential functions for human health1. During the first two years of life gut microbiota experiences the most relevant changes, reaching complexity and maturity later in life2,3.

Gut microbiota development is shaped by the influence of several environmental and host factors. These include gestational age, mode of delivery, type of feeding and antibiotic use, between others4. For example, vaginally delivered babies come in contact with the maternal vaginal and faecal microbiota, whereas caesarean-section delivered babies do not. This lack of exposure to microbes has been linked to a deviating gut microbiota in infants. Preterm infants endure tough conditions early in life, including extensive antibiotic treatments or artificial nutrition, which results in a disruption of gut microbiota development and composition5.

Importantly, disruptions in gut microbiota in infancy have been linked to higher risk of long-term development of immune and metabolic disorders, including allergies, diabetes, obesity and irritable bowel syndrome (IBS)6

A healthy microbiota development during the first 1000 days of life promotes long-term benefits.

Bifidobacteria are the dominant bacterial group in the gut of healthy babies. Its abundance progressively reduces with age, as gut microbiota diversity increases2. Bifidobacteria play key roles in the normal development of the gut microbiota, use of dietary compounds and maturation of the immune system6.  Importantly, feeding pattern has major impact in gut microbiota during the first weeks of life. Formula-fed infants present lower levels of bifidobac­teria, whereas breastfed infants develop a bifidobacteria-dominated microbiota, which has been linked to several health benefits1.

The successful colonization of bifidobacteria in the gut of breastfed babies is partly due to the beneficial nutrients of breastmilk, inclu­ding human milk oligosaccharides (HMOs)7. HMOs are complex su­gars found in great abundancy in breastmilk. HMOs are indigestible by the infant, but are easily and specifically metabolised by some bifi­dobacteria. In a symbiotic relationship, HMOs promote bifidobacte­rial growth, contributing to the enrichment of the babies’ microbiota6.

Formula-fed babies can benefit from supplementation with probiotics containing bifidobacteria strains of human origin.

AB-KOLICARE™ contains Bifidobacterium longum KABP™ 042, a human-residential bifidobacteria found naturally in the human gut or breast milk. The strain can effectively digest HMOs, and has other beneficial properties influencing the gut microbiota of babies. Plus, AB-KOLICARE™ probiotic formula has been specifically tested in formula-fed babies, with positive clinical results on infant colic and gut microbiota development.

Know more about our probiotic strains for pediatric health here

Author: Claudia Prat (Human Biologist) and Marta Pérez, PhD (Microbiologist)


1. Martin, R. et al. Early-Life Events, Including Mode of Delivery and Type of Feeding, Siblings and Gender, Shape the Developing Gut Microbiota. PLoS One 11, e0158498 (2016). 2. Kato, K. et al. Age-Related Changes in the Composition of Gut Bifidobacterium Species. Curr. Microbiol. 74, 987–995 (2017). 3. Avershina, E. et al. Bifidobacterial succession and correlation networks in a large unselected cohort of mothers and their children. Appl. Environ. Microbiol. 79, 497–507 (2013). 4. Arboleya, S., Watkins, C., Stanton, C. & Ross, R.P. Gut bifidobacteria populations in human health and aging. Frontiers in Microbiology vol. 7 (2016). 5. Milani, C. et al. The First Microbial Colonizers of the Human Gut: Composition, Activities, and Health Implications of the Infant Gut Microbiota. Microbiol. Mol. Biol. Rev. 81, (2017) 6. Yamada, C. et al. Molecular Insight into Evolution of Symbiosis between Breast-Fed Infants and a Member of the Human Gut Microbiome Bifidobacterium longum. Cell Chem. Biol. 24, 515–524 (2017). 7. Zivkovic, A. M., German, J. B., Lebrilla, C. B. & Mills, D. A. Human milk glycobiome and its impact on the infant gastrointestinal microbiota. Proc. Natl. Acad. Sci. U. S. A. 108, 4653–4658 (2011).