Two new studies published in the journal Science suggest the communities of bacteria living in our digestive tracts can determine how much weight can be gained, even on a diet of insufficient nutrients. The research, published Thursday, took gut bacteria from healthy and unhealthy young children in Malawi and transplanted them into mice. They found that certain microbes could encourage normal growth in those who are undernourished.
Researchers at the Washington University School of Medicine drew microbe samples from feces of both healthy and malnourished children between the ages of six months and 18 months and transferred them to lab mice. They found the undernourished children had gut microbiota that had not evolved normally as they aged, and that the immature gut bacteria may be a major factor in their stunted growth.
To prove this, the researchers fed the lab mice a diet similar to undernourished children in Malawi that "does not fulfill the needs of humans or mice," according to the first study, including kidney beans, peanuts, pumpkins, and peeled bananas.
"We envision that, together with nutritional therapy, microbial interventions using selected bacterial strains may represent a novel and complementary strategy"
Over the course of five weeks, researchers found that mice with healthy microbiota were able to gain weight while those who received the immature gut bacteria were shown to have impaired growth, altered bone morphology, and abnormalities in the muscle, liver, and brain, despite the same diet.
"Mice colonized with microbiota from healthy donors gained significantly more weight and lean body mass than mice colonized with microbiota from undernourished donors," the Washington University study said.
The results offer a new vision for treatment for the nearly 180 million children in the world who experience the effects of malnutrition, according to Science.
"We envision that, together with nutritional therapy, microbial interventions using selected bacterial strains may represent a novel and complementary strategy to buffer the adverse effects of chronic undernutrition on human postnatal growth," the study said.
But more research is still needed, including pinpointing the exact microbes that help foster growth in undernourished children, before treatment can be developed. In the second study, researchers at University of Lyon found that two microbes alone, Ruminococcus gnavus and Clostridium symbiosum, fixed hormonal mechanisms that led to stunted growth in malnourished children.
The researchers said they must determine what kind of therapy can be used to support the growth of age-appropriate microbiota and how those can be regulated, including probiotics, fecal transplants, and other interventions. While more tests must be done to create specific treatment plans for children, microbiologists are already calling the implications of the study "profound."
It's unclear whether using probiotics or fecal transplants to reverse or prevent damage in undernourished children is more practical, however, than simply giving them food.