A paper published last month in Cell by AMI Scientific Advisory Board member Marty Blaser at NYU investigated the role and conseqeunces of low dose antibiotics early in life in mice. Blaser and his team took two groups of infantile mice, and exposed one group with low doses of penicillin and left the other group alone. The mice that were given the low doses of antibiotics ended up becoming overweight later in life compared to the group that was not given antibiotics. Then, the team took the microbiome of each group and transplanted it into germ-free infantile mice that were given no antbiotics. The germ-free mice that were given the microbiome of the lean mice were lean later in life, while the germ free mice that were given the microbiome of the obese mice were obese later in life. In addition, when both groups of mice were given high fat diets, the group with low dose antibiotics gained more weight.

Interestingly, the antibiotic group of mice still had an abundance of highly diverse bacteria, however these mice were lacking certain strains that were found in the normal mice, and thus may be critical to later health. The team discovered rather unambiguously that the obesity was induced by the microbiome. The mechanism for how this occurs is still unknown, but the researchers suggested changes to normal metabolic processes and the immune system that could occur. Overall this study shows the importance of a healthy microbiome early in life and the dangers of antibiotics early in life, because they both can have lasting consequences into adulthood.