Gut Microbiota and the Developing Child

by Ayten Salahi

Undernutrition poses a formidable threat to the health and life trajectory of children around the world. A new study examines the role of gut microbiota in modulating nutritional status and early life development, and sheds light on bacterial transplants as a potential new method to tackle this longstanding challenge.

The human gut microbiome is the bacterial ecosystem that lives predominantly in the digestive tract and plays a significant role in our immune response, neurological networks, and both our mental and physical development throughout life. The delicate balance of ‘good’ and ‘bad’ gut bacteria – or gut maturity – partially determines a developing child’s ability to absorb critical nutrients through food. Without that ability during early life, or without medical interventions to restore that ability, children are likely to manifest long-term health consequences associated with childhood undernourishment, including physical stunting, immune dysfunction, and neurodevelopmental issues. Childhood undernourishment has also been linked to permanent impairments to health and human capital, that impact both extant and future generations.

The ‘solution’ to childhood undernutrition is multivariate. As scientific understanding of microbiota continues to evolve, researchers and healthcare practitioners have begun to shift their focus towards examining how the microenvironments of our gut bacteria impact our macroenvironments, and whether these microenvironments could signal potential new treatment targets to alleviate the global burden of childhood undernutrition.

Bacterial transplants have been identified as one potential treatment. A study from Blanton et al. examined whether developmental outcomes could be inherited through microbiota – specifically, through fecal transplants. They tested what would happen if germ-free mice were transplanted with the gut bacteria of both ‘healthy’ and  ‘severely stunted’ infants and children, all of which were fed a traditional Malawian diet of cornmeal, peanuts, and kidney beans. The results showed that when germ-free mice were transplanted with fecal transplants from severely undernourished children, the mice manifested stunted growth, impaired bone morphology, and metabolic abnormalities in the muscle, liver, brain, and immune system. This study therefore suggests that gut bacteria play a role in the transference of developmental outcomes.

Findings from the same study also suggest that microbiota transplants from healthy donors could potentially prevent growth impairments and undernourished health outcomes in recipient animals, depending on the age of the donor and the type of bacteria. When researchers co-housed mice that had just received microbiota from either 6-month-old healthy donors or severely undernourished donors, microbiota from the healthy donor group overpowered and displaced the microbiota from the undernourished donor group, and prevented developmental impairments in both groups.  More research is needed to confer these findings in humans, but the results of this study present the interesting possibility that gut immaturity can be prevented and repaired through transplantation of microbiota from healthy donors. Future research must also be conducted to examine whether bacterial transplants play a role in preventing long-term mental, physical, and socioeconomic consequences of early life undernourishment, or constitute any reduction to the global burden of childhood undernutrition.

Study of microbiota in the developing child offers a compelling new lens with which to examine health inequity at the microscopic scale, with macroscopic implications for therapeutic interventions in community health. Adequate nutrition is the cornerstone of human development, and a growing body of evidence suggests that gut microbiota play an important role in promoting early life nutritional status. The potential therapeutic use of bacterial transplants could have significant implications for global nutrition programs seeking to identify new levers to improve childhood nutrition, particularly in resource-poor settings. However, gut microbiota therapeutics constitute only a small and largely theoretical part of the much bigger and more complex picture that is global nutrition. Pervasive issues around sanitation, hygiene practices, and access to potable water and nutritious food continue to constitute some of the greatest challenges to global health worldwide.

Ayten Salahi is a first-year FPAN MS and RD candidate, and is dedicated to the future of policy, programming, and clinical practice in sustainable diets. Ayten came to Friedman after working as a molecular and clinical researcher in neuropharmacology and diabetes management for nearly 8 years.

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