Are antibiotics making your kids obese?

Illustration for article titled Are antibiotics making your kids obese?

The science of studying the human gut microbiome is still in its early days — but research into this area is beginning to reveal some pretty startling things. Take two recent studies published in Nature and the International Journal of Obesity, both of which indicate that the use of antibiotics in young children could be leading to a higher risk of obesity. Are antibiotics making devastating changes to your child's intestinal bacteria?


The Washington Post's Hristio Boytchev says the two independent studies could broaden our sense of how obesity is caused — and why we might need to be more cautious of how and when antibiotics are used.

In the paper that appeared in Nature, scientists recount an experiment where they treated young mice with low doses of antibiotics and found that the mice became more obese, even if they didn't become larger overall. Explains Boytchev:

The researchers suspected that changes in the intestine bacteria were responsible. They surveyed the bacteria using genetic methods and found that while treated and untreated mice had a similar total count of bacteria species, their compositions seemed to diverge. Some species of bacteria, previously shown to be associated with obesity in mice, were found at a higher concentration.

The scientists then did a genetic analysis of the bacteria's metabolism and found that some genes responsible for fat synthesis showed a higher activity in the treated mice. Overall, the scientists concluded that the treated mice had bacteria that were more efficient in digestion.

The second study looked at human children, examining statistical data from almost 11,000 kids in Avon, England. Writes Boytchev:

The researchers found that children, who were given antibiotics in their first six months, had a higher incidence of obesity later. The difference was most pronounced at about 3 and tended to teeter off at about 7, the latest time analyzed. Obesity at that age correlated slightly with antibiotics during the toddler stage. The differences remained even when the scientists took additional factors such as diet and activity into account. Overall, the research corroborated earlier findings by a Danish study while providing additional detail.

All this said, the scientists admit this is all very preliminary. And indeed, what they're showing here is correlation and not causation. What needs to happen next, as Boytchev correctly notes, are further studies into digestion and how antibiotics contribute to the makeup of the gut microbiome.

The original studies can be found in Nature and The International Journal of Obesity.


Image: Jezper/


Dr Emilio Lizardo

In the human study (ignore the one done in mice - I always do) in the results they say "...exposure from 15 to 23 months was significantly associated with increased BMI Z-score at 7 years..." but in the conclusions they say "Exposures later in infancy (6–14 months, 15–23 months) are not consistently associated with increased body mass." Somebody want to explain that to me? I'm not paying for full access.