The New York Times investigates the strange history of American antibiotics – and how the medicine hailed as a “superdrug” in the 1940s might have made us an overweight nation:
And yet, scientists still could not explain the mystery of antibiotics and weight gain. Nor did they try, really. According to Luis Caetano M. Antunes, a public health researcher at the Oswaldo Cruz Foundation in Brazil, the attitude was, “Who cares how it’s working?” Over the next few decades, while farms kept buying up antibiotics, the medical world largely lost interest in their fattening effects, and moved on.
In the last decade, however, scrutiny of antibiotics has increased. Overuse of the drugs has led to the rise of antibiotic-resistant strains of bacteria — salmonella in factory farms and staph infections in hospitals. Researchers have also begun to suspect that it may shed light on the obesity epidemic.
In 2002 Americans were about an inch taller and 24 pounds heavier than they were in the 1960s, and more than a third are now classified as obese. Of course, diet and lifestyle are prime culprits. But some scientists wonder whether there could be other reasons for this staggering transformation of the American body. Antibiotics might be the X factor — or one of them.
To find out, Dr. [Martin] Blaser [of New York University] and his colleagues have spent years studying the effects of antibiotics on the growth of baby mice. In one experiment, his lab raised mice on both high-calorie food and antibiotics. “As we all know, our children’s diets have gotten a lot richer in recent decades,” he writes in a book, “Missing Microbes,” due out in April. At the same time, American children often are prescribed antibiotics. What happens when chocolate doughnuts mix with penicillin?
The results of the study were dramatic, particularly in female mice: They gained about twice as much body fat as the control-group mice who ate the same food. “For the female mice, the antibiotic exposure was the switch that converted more of those extra calories in the diet to fat, while the males grew more in terms of both muscle and fat,” Dr. Blaser writes. “The observations are consistent with the idea that the modern high-calorie diet alone is insufficient to explain the obesity epidemic and that antibiotics could be contributing.”
The Blaser lab also investigates whether antibiotics may be changing the animals’ microbiome — the trillions of bacteria that live inside their guts. These bacteria seem to play a role in all sorts of immune responses, and, crucially, in digesting food, making nutrients and maintaining a healthy weight.