Antibiotics have been added to animal feed for decades to promote weight gain. And, apparently, the effect is similar on humans. (Photo: Getty Images)
New research has found that children who frequently take antibiotics gain weight faster on average than those who have never taken antibiotics.
For the study, scientists at Johns Hopkins University analyzed nearly 164,000 medical records of children ages 3 to 18 who had pediatric exams between 2001 and 2012. Researchers discovered that one in five children had been prescribed antibiotics at least seven times. By the time those children were 15, on average, they weighed three pounds more than children who didn’t take antibiotics.
The results were published in the International Journal of Obesity.
While the findings sound shocking, lead study author Brian S. Schwartz, MD, a professor of environmental health sciences, epidemiology, and medicine at the Johns Hopkins Bloomberg School of Public Health, tells Yahoo Health that antibiotics have been added to animal feed for decades to promote weight gain. And, apparently, the effect is similar on humans.
Taking more antibiotics only exacerbates the problem, says Schwartz: “The more the cumulative number of antibiotics, the greater the weight gain.”
While his team didn’t investigate why this correlation exists, Schwartz says it may be due to changes in gut microbiota, the microorganisms that live in our intestines which previous research has found can influence everything from our hearts to our minds.
“Other studies document that antibiotics change the gastrointestinal tract microbiota and that such changes can be permanent if antibiotics are given at the wrong time or repeatedly,” he says. Consequently, nutrients can be broken down differently in a person’s body after antibiotic use, and the body may even absorb more calories.
This isn’t the first study to link antibiotics with weight gain in humans. Research published earlier this year in the journal Nature found that children whose mothers took antibiotics during their pregnancy were more likely to be overweight or obese.
Related: When You Should Skip Antibiotics
While Schwartz’s research stopped tracking children after the age of 18, he says it doesn’t mean that the weight gain stopped once they hit adulthood. “My guess is that the effect will continue into adulthood, and may lead to accelerated weight gain during adulthood, too,” he says.
The findings are troubling, Sanford Vieder, DO, founder of Michigan’s Lakes Urgent Care, tells Yahoo Health. “There is a message here: Kids are getting overprescribed antibiotics and it’s really troubling,” he says.
Vieder says care providers are often pressured to prescribe antibiotics by parents who think the drugs are the only thing that will help a sick child. “When it’s likely a viral infection, you know it won’t be impacted by an antibiotic, but you also know that a parent or patient could give you a poor review online because you’re not giving them what they want,” he says. “There’s a little bit of a push to just write the antibiotic prescription.”
Not only can it cause weight gain, as the study found, it can also create antibiotic resistance. Antibiotic resistance occurs when an antibiotic has lost its ability to control or kill bacteria, and it’s often caused by overuse or misuse of the drug. The Centers for Disease Control and Prevention calls the phenomenon a “growing problem” in the U.S. and around the world.
When antibiotic resistance occurs, it can cause even more problems for the patient. “When people really do need these antibiotics for a particular infection, it may not be effective,” Vieder explains. “That’s really scary.”
The overuse of antibiotics has also been blamed for a growing number of antibiotic-resistant bacteria. New research published in the journal Infection Control & Hospital Epidemiology found that drug-resistant E.coli infections are on the rise. Research has also found that MRSA, a serious staph infection resistant to many forms of antibiotics, now kills more people each year than HIV.
Both Vieder and Schwartz urge parents and patients to listen to their doctor when it comes to antibiotic use. “If your provider doesn’t think that an antibiotic is needed, accept that,” says Vieder. “They’re not going to steer you wrong.”
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