Giving Babies Antibiotics May Cause Obesity Later in Life

The negative effects of penicillin on good gut bacteria early in life may make it easier for children to become obese when they are older.

A study has found a possible link between giving young children antibiotics and them developing obesity later in life. The study focused on penicillin’s effects; however, the problem appears not to be caused by penicillin itself, but rather by the damage it does to certain types of good bacteria in the digestive tract.

The study, by microbiologist Martin Blaser at New York University, was conducted on mice. It adds to other studies, which found that children who were given antibiotics before 6 months of age were more likely to be overweight at 7 years old. Blaser believes there’s a “window of time” during which penicillin can have the greatest consequences on good bacteria. He thinks it’s somewhere between 6 months and 3 years old.

Approximately 100 trillion bacteria live in and on the typical human. As we’ve learned in recent years, part of a healthy life includes good microbes. Blaser’s study found that disruption of the “microbiome” of the mice during their first month of life resulted in 25 percent more weight later. It also appeared to worsen the effects of a high-fat diet, and males were affected more than females.

The question for parents is: Should you keep your sick child off antibiotics because of these results? No, says Naveed Sattar, professor of metabolic medicine at Glasgow University. While the results are interesting, he says, “Antibiotics in children or newborns should be given on the basis of clinical needs, whereas the usual advice about lifestyle remains the most important means to tackle obesity.”

Blaser agrees, to a point. “If a kid is very ill, there is no question that they should get antibiotics, but if it’s marginal, perhaps the doctor should be saying, ‘Let’s wait a day or two’ before taking another look. Doctors give out antibiotics thinking they won’t do any harm, but this provides evidence that they might,” Blaser says.

On a related matter, the federal government is taking steps to combat antibiotic-resistant bacteria, one result of overprescribing antibiotics. President Obama recently signed an executive order outlining instructions to federal departments and agencies. Part of the order reads, “Controlling the development and spread of antibiotic resistance is a top national security and public health priority.” The Centers for Disease Control and Prevention (CDC) says antibiotic-resistant infections are associated with 23,000 deaths and 2 million illnesses in the United States each year.