Evaluating Treatments for Childhood Malnutrition Based on Changes in Gut Bacteria
A team of U.S. and Bangladeshi scientists discovered that children who are malnourished do not harbor gut bacteria typical for their age, even several months after receiving a nutritional intervention. The persistence of this “immature” collection of gut bacteria may be a reason why the children do not grow well even after receiving nutrient-dense food. Moderate or severe forms of malnutrition affect a large number of children living in developing countries, such as Bangladesh. This malnutrition typically develops very early in life, between 3 and 24 months. Therapeutic interventions, such as the use of either a specially prepared, nutrient-dense processed food or indigenous foods high in calories and protein, have short-term, but not lasting effects in terms of sustaining healthy growth and development. The community of microbes inhabiting the gut is known to play an important role in assisting their human host with many important functions, such as extracting nutrients from the diet and facilitating new blood vessel formation in the intestine. Scientists wondered whether malnutrition early in life might disrupt the establishment of a healthy, diverse microbial community, thereby limiting the impact of subsequent nutritional interventions. To test this idea, they identified the different microbial species present in fecal samples collected from children living in an impoverished urban area of Dhaka, Bangladesh. Using a technique that distinguishes among different types of bacteria, they were able to identify which bacterial species were present. They first used this method to characterize the microbial makeup of a group of children showing healthy growth and development for their age living in this part of the world. They confirmed this model of a healthy, or “mature,” microbial community in another group of local, healthy children. Then, they compared them to severely malnourished children who were treated in a hospital in Dhaka for a few weeks with either a standard ready-to-use therapeutic food or a locally produced combination of rice and lentils with other nutrients. While both nutritional interventions improved growth of the malnourished children, they remained underweight and below normal height compared to healthy children. Fecal samples taken from the malnourished children before, during, and after treatment revealed a persistent immaturity in their gut microbial communities, such that they lacked bacterial species typically found in well-nourished children of a similar age. These findings suggest new strategies that might be used to improve the treatment of childhood malnutrition by bolstering the health of the gut microbial community, such as through more prolonged dietary interventions or development of targeted probiotics.