In young children with severe acute malnutrition, immaturity in gut microbiota development might persist despite nutritional interventions. These findings could explain why therapeutic food interventions have helped reduce mortality but have been unable to completely restore healthy growth in many of these children.

Jeffrey Gordon and colleagues investigated the gut microbiotas of healthy and malnourished children in Bangladesh. The first step of the study was to establish the normal features of the developing gut microbiota in healthy children for 2 years from birth. To that end, monthly stool samples were collected from 50 healthy Bangladeshi children. Information about the gut microbiotas of these children was used to create a model that could calculate a 'relative microbiota maturity index' and a 'microbiota-for-age Z-score'.

Credit: NPG

“Using this microbial signature of normal gut microbial community maturation, we evaluated the gut microbial communities of 64 severely malnourished children before, during and after they received standard food-based interventions,” explains Gordon. Compared with healthy children, severely malnourished children were found to have microbiota immaturity both at the start and end of treatment. Food interventions did lead to improvements, but these changes were short-lived. Moreover, although these children did gain weight, their weight still remained below normal and their health was not fully restored.

The researchers also investigated the gut microbiotas of children with moderate acute malnutrition, and found that these children also had microbiota immaturity.

Finally, the team were interested in whether their model of gut microbiota maturity was specific for Bangladeshi children, or whether it had relevance in other geographic regions. They found that the model applied to a cohort of 47 healthy Malawian twins and triplets.

“These new measuring tools for defining the maturation of the gut microbial community 'organ' expand our view of human development following birth, provide a new way of classifying malnourished states, establish a new measure for determining the effects of current therapies, and catalyze thinking about new forms of therapy,” says Gordon. The authors suggest that administering gut microbes as part of a therapeutic intervention, or extending the length of intervention, might help to achieve lasting gut microbiota maturity.