Stunting, the impaired growth and development of children, affects an estimated 155 million children per year. This represents roughly 25% of the world’s children and there exists a substantial lack of knowledge regarding the underlying causes and potential treatments. Current thinking on stunting hypothesizes that contributing factors such as inadequate psychosocial stimulation, poor nutrition, and recurrent infection are to blame. New research, however, is indicating that the microbial community of the small intestine, an organ essential for digestion and nutrient absorption, may be another contributing factor.
New data, published in PNAS by Afribiota investigators, including Microbiome Insights co-founder Dr. Brett Finlay, found that children suffering from stunting are affected by bacterial overgrowth in the small intestine and possess a microbial community made up from mainly oropharyngeal bacteria. Researchers studied duodenal and gastric samples of children with stunting, aged 2-5 years, in comparison with healthy children living in sub-Saharan Africa. Using 16S Illumina amplicon sequencing and semi-quantitative culturing methods they characterized the microbial communities of these children and found the small intestinal bacterial overgrowth in children with stunting.
The small intestines of children with stunting harboured bacterial species normally found in the oropharyngeal cavity. This overgrowth was also represented in fecal samples from the stunted children—which suggested a path toward developing non-invasive biomarkers for this condition. Furthermore, in stunted children Escherichia coli, Shigella species and Campylobacter species were more prevalent and Clostridia, well-known butyrate producers, were reduced.
These results indicate stunted children are experiencing a de-compartmentalization of the gastrointestinal tract, possibly a result of poor oral hygiene, recurrent or chronic rhino-pharyngeal infections, a hypo-chloric environment in the stomach (which weakens the natural barrier of stomach acidity), or other changes to the stomach environment which reduce its ability to kill unwanted bacteria. Importantly, these changes were seen in two geographically and nutritionally distinct populations, providing strong evidence that bacterial overgrowth is a conserved feature of the stunting condition itself.
The exact role of the oropharyngeal bacteria in intestinal inflammation, while yet to be determined, may provide vital information toward understanding the pathophysiology of stunting and potential new treatments.
Vonaesch P, Morien E, Andrianonimiadana L, et al. Stunted childhood growth is associated with decompartmentalization of the gastrointestinal tract and overgrowth of oropharyngeal taxa. Proc Natl Acad Sci U S A. 2018; 155: E8489-E8498.