Early social and environmental exposures can have large and lasting effects on child development and adult health. One of the systems in the human body that is vulnerable to external influence is the gut microbiome: the community of bacteria that live in the gastrointestinal tract. Some variations in the human gut microbiome are important because they are linked to the incidence and mortality of various diseases.
In the United States, adult gut microbiome diversity correlates with self-reported race and ethnicity, even though there is no genetic or biological reason for this. In this context, scientists believe that race and ethnicity are proxies for inequitable exposure to social and environmental determinants of health due to structural racism.
But the timing and conditions under which gut microbiome differences first appear have been a mystery. A study from Washington University in St. Louis, The Pennsylvania State University and Vanderbilt University highlights a critical development window during which racial differences in the gut microbiome emerge.
Gut microbiome variation associated with race and ethnicity arises after 3 months of age and persists through childhood, according to the new research published Aug. 17 in PLOS Biology.
“The differences that we see are not present at birth, or even shortly after,” said Elizabeth Mallott, PhD, an assistant professor of biology in Arts & Sciences at Washington University, first author of the new study. She and her collaborators analyzed data from eight previous studies, including 2,756 gut microbiome samples from 729 U.S. children between birth and 12 years of age.