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Linear growth delay, in which normal growth in children is stunted, affects millions of children under the age of 5 years around the world yearly. Caused in part by malnutrition, it primarily affects children living in difficult economic conditions that expose them to sewage and waste. The consequences of stunted growth carry on into adulthood, including decreased income potential and health complications.
Stunting is associated with changes in the microbial community of the small intestine, a compartment vital for digestion and nutrient absorption. Nutrition, inflammation in the gastrointestinal system and an imbalance of the bacteria comprising the microbiota are the major cause.
In a new, multi-institutional study led by Pascale Vonaesch of the Pasteur Institute, researchers have collected evidence from a large cohort of children living in sub-Saharan Africa; Bangui, Central African Republic, and Antananarivo, Madagascar, suggesting that stunted growth could be caused by a massive overrepresentation in the intestine of bacteria that normally reside in the oropharyngeal cavity.
Although the Central African Republic and Madagascar are among the countries with the highest prevalence of linear growth delay, representing half of all affected children under the age of five, they have never before been included in an analysis of pediatric environmental enteropathy, the syndrome proposed as an underlying condition of stunted growth.
The study reports that the actual composition of small intestinal bacterial overgrowth (SIBO) in stunted children-the similarity of microbiota in the intestines of these children with that of the stomach and duodenum. A traceable microbiological signature of stunting in feces characterized by the overrepresentation of oropharyngeal species, which could be used for diagnosis.
These findings were conserved between the countries included in the study, indicating the probability that this common feature could be an underlying cause of stunted growth. The authors propose that stunting is strongly associated with decompartmentalization of the gastrointestinal tract characterized by overabundance of oropharyngeal bacteria that extends from the stomach to the colon.
This challenges the current view of stunting, in which recurrent infections by enteric pathogens inflame and overstimulate the small intestine. It also highlights the complicated relationship between the intestinal microbiome, metabolism, human development, and the surrounding environment.
The study confirms the suspected overrepresentation of enteropathogenic bacteria in the duodenum of stunted children, but extends the current picture by demonstrating a previously unknown microbial decompartmentalization of the oropharyngeal to gastrointestinal tract.