Mouse Model Shows How Antibiotic Use In Early Life Leads To Weight Gain

A study using mice shows how subtherapeutic antibiotic use in early life affects gut microbial communities, or microbiomes, and leads to increased body mass (Nature, DOI:10.1038/nature11400). The results indicate that early antibiotic treatment in humans and other animals could have profound metabolic consequences.

Scientists have long known that long-term antibiotic use, a practice common in livestock farming, makes animals gain weight and affects gut microbial environments, but they lacked detailed mechanisms or explanations.

Using recent advances in microbio­mics, Martin J. Blaser, chair of the department of medicine at New York University School of Medicine, and colleagues treated young mice with subtherapeutic doses of antibiotics such as penicillin and vancomycin for seven weeks. Although the treated mice weighed the same as their untreated counterparts, their fat mass was significantly greater.

The group observed changes in microbe metabolism and host genetic responses. For example, the gut environment altered by the antibiotics allows microbes that digest complex carbohydrates to flourish. Therefore, greater quantities of the products of this digestion—short-chain fatty acids—are shunted to the mice’s livers, increasing fat production.

“To my knowledge, this is the first study to experimentally induce changes in body composition by administering antibiotics and manipulating the micro­biota,” says Dag Henrik Reikvam of Oslo University Hospital in Norway.