Antibiotics aren’t only used by farms to prevent infection; they’re also used to plump up chickens, cows, pigs, and turkeys. Now, researchers suggest that antibiotics given to young children could have the same weight-gaining effect.
However, leaders in the field are unconvinced by the data. Microbiologist David Relman, who investigates the microbiome at the Stanford University School of Medicine told ScienceNOW that the work is "provocative" but that some of the data are "a bit vague and unclear."
Some researchers think that low dose antibiotics make farm animals heftier by altering their gut microbiota, which is responsible for digesting food and making nutrients available to the host. (For a critical review of this practice, see “Antibiotics in the Animals We Eat.”) When researchers from New York University School of Medicine gave young mice low doses of antibiotics, on a schedule similar to that given to farm animals, they saw the mice develop more fat stores than controls, in work published yesterday (August 22) in Nature. Analysis of the mouse gut microbiota showed that the microbial community had shifted to include a greater proportion of Firmicutes species, which the author speculated could make more calories available to the host than other groups of commensal bacteria.
A second paper by the same lead author, published in the International Journal of Obesity, looked at children in the United Kingdom treated with antibiotics in the first 6 months of their lives compared to untreated children. Comparing the weight of the children at 38 months old, researchers saw a higher chance of overweight measures in children who were given antibiotics.
But while there may have been a small increase in weight at 38 months, critics say, there was no association between antibiotic use and weight at 7 years. In addition, the mice used in the study were given antibiotics from the time they were weaned from their mother until maturity. "We never give antibiotics to children continuously from the time they wean to the time they reach sexual maturity," Relman told ScienceNOW.