Manipulating the gut microbes of undernourished children could help them to gain weight, three laboratory studies in mice and pigs suggest.

Malnourished children can struggle to gain weight even on high-nutrient diets, and studies have suggested that under-nutrition stops their gut microbiomes from maturing. A team led by Jeffrey Gordon at Washington University in St. Louis, Missouri, transplanted gut microbes from undernourished and healthy children from Malawi into germ-free mice, and found that mice given microbes from healthy children gained more weight and muscle than did mice with the malnourished microbiomes. The team identified microbial species associated with these gains, and delivering two species to the guts of mice that had malnourished microbiomes boosted the animals' growth.

Martin Schwarzer and François Leulier at the University of Lyons, France, and their team found that giving malnourished mice a strain of Lactobacillus plantarum bacteria helped the mice to gain weight by restoring their growth hormone production. In a third study, Gordon and his colleagues identified a sugar in breast milk that promoted growth in mice and piglets harbouring microbes from a malnourished child.

Science (2016); Science 351, 854–857 (2016) ; Cell (2016)