2017-10-26 20:02:06 UTC

What We Know about the Gut Microbiome and Human Development

Oct. 27, 2017

Did you know that we can predict a child’s age based on the bacteria present in a stool sample? Dr. Geoffrey A. Preidis summarizes current knowledge around this fascinating topic.

By Geoffrey A. Preidis, MD, PhD, Baylor College of Medicine; scientific advisory board member for the AGA Center for Gut Microbiome Research and Education

Newborns enter a world that is teeming with microorganisms. Some microbes will colonize the gut and promote child growth by synthesizing vitamins, facilitating immune and enteric nervous system development, and enhancing energy extraction from the diet. However, the composition and function of gut microbiota change dramatically across one’s lifespan.

Gut microbial communities mature in a predictable pattern called “ecological succession.” Initial colonization of a newborn is influenced by many factors including prenatal nutrition and medications, cesarean vs. vaginal delivery, the baby’s genetic and intestinal mucus composition, early-life antibiotic exposure, and breast milk vs. formula feeding. These initial communities are not very diverse and are dominated by microbes from the mother’s skin and by bacteria that metabolize breast milk carbohydrates. Also, the immature newborn gut has a high redox potential, so oxygen-tolerant organisms including Lactobacillus and Escherichia coli thrive initially— but as oxygen is reduced, they are gradually replaced by strict anaerobes. The most dramatic increase in gut microbiota diversity in one’s lifetime occurs when infants are weaned from exclusive breast milk or formula to a wide variety of foods. Although development is mostly complete by the toddler years, pre-adolescents still have distinct microbiome profiles compared to adults. This suggests that the gut microbiome matures over decades — much like its human host. Incredibly, this pattern of succession can allow one to predict a child’s age based on the bacteria present in a stool sample!

We still have much to learn about the microbiome in human development. We need to more accurately identify all gut microorganisms (including viruses and fungi) and better understand their biological functions. Because early postnatal microbial communities are relatively unstable — at no other stage in a healthy person’s life are microbiota in such a state of flux — it is difficult to determine which microbes or microbial functions associate with child health vs. disease. Furthermore, microbes detected in stool are often different from those that colonize the large or small bowel including the gastrointestinal mucus layer — where they might have a more direct impact on health. It is also difficult to determine whether specific microbes actually promote health, or whether they simply thrive in a healthy, disease-free intestine.

One day clinicians might be able to modify a child’s growth trajectory, vitamin stores and other developmental parameters by therapeutically manipulating the gut microbiota. But a great deal of research is needed before these intriguing possibilities are ready for clinical practice.

Recommended Reading

  • Lozupone CA, Stombaugh JI, Gordon JI, Jansson JK, Knight R. Diversity, stability and resilience of the human gut microbiota. Nature. 2012 Sep;489(7415):220-30. https://www.ncbi.nlm.nih.gov/pubmed/22972295
  • Subramanian S, Blanton LV, Frese SA, Charbonneau M, Mills DA, Gordon JI. Cultivating healthy growth and nutrition through the gut microbiota. Cell. 2015 Mar 26; 161(1):36–48. https://www.ncbi.nlm.nih.gov/pubmed/25815983
  • Hollister EB, Riehle K, Luna RA, Weidler EM, Rubio-Gonzales M, Mistretta TA, Raza S, Doddapaneni HV, Metcalf GA, Muzny DM, Gibbs RA, Petrosino JF, Shulman RJ, Versalovic J. Structure and function of the healthy pre-adolescent pediatric gut microbiome. Microbiome. 2015 Aug 26;3:36. https://www.ncbi.nlm.nih.gov/pubmed/26306392

This article is part of the Oct. 27 AGA Microbiome Update, which was emailed to all AGA members.

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