Despite substantial economic improvement in many countries in the past 25 years, still more than 30 million children worldwide suffer from moderate acute malnutrition. Current treatments have limited effectiveness, and much remains unknown about the pathogenesis of this condition. These children with moderate acute malnutrition have an altered development of their gut microbiota. In this study by Chen and colleagues, supported by the Bill and Melinda Gates Foundation, the authors provided a microbiota-directed complementary food prototype (MDCF-2) or a ready-to-use supplementary food to 123 slum-dwelling Bangladeshi children with moderate acute malnutrition between the ages of 12 months and 18 months. The supplementation was given twice daily for 3 months, followed by 1 month of monitoring. The weight-for-length and weight-for-age z scores showed a benefit of MDCF-2 nutrition on growth over the course of the study. Receipt of MDCF-2 was linked to the magnitude of change in levels of 70 plasma proteins and of 21 associated bacterial taxa that were positively correlated with the weight-for-length z score. These proteins included mediators of bone growth and neurodevelopment. These findings provide support for MDCF-2 as a dietary supplement for young children with moderate acute malnutrition and provide insight into mechanisms by which this targeted manipulation of microbiota components may be linked to growth. Larger trials will need to be performed in other geographic regions to further assess the efficacy of this therapeutic approach for treating childhood undernutrition. The plasma and microbiota biomarkers identified here may be helpful to better characterize and stratify children for future dietary interventions.