CAFO

In the country’s ongoing Battle of the Bulge, leading culprits have been identified including our fast-food-obsession, those gigantic, sugary soft drinks, and trans fats. But what about antibiotics?

Writing for Mother Jones, food and ag blogger, Tom Philpott, narrows in on the rising obesity epidemic and the use of antibiotics in factory farming. More than 80 percent of the nation’s antibiotic supply in 2009 went to animals, and not just to treat infection: “Back in the 1940s, scientists discovered that regular low doses of antibiotics increased “feed efficiency”—that is, they caused animals to put on more weight per pound of feed.” According to Philpott, “No one understood why, but farmers seized on this unexpected benefit. By the 1980s, feed laced with small amounts of the drugs became de rigueur as US meat production shifted increasingly to factory farms.”

Now, scientists may have figured out how antibiotics lead to weight gain. Philpott writes: “They make subtle changes to what’s known as the “gut microbiome,” the teeming universe populated by billions of microbes that live within the digestive tracts of animals.”

Philpott cites a study published in a recent issue of the journal, Nature, that found notable changes to gut microbiota in mice fed antibiotics. And another side effect of the prolonged antibiotic exposure: weight gain. The mice packed on 10 to 15 percent more fat than the control group.  The reason, according to the study researchers, is most likely that the antibiotics increase the ability of certain microbes to break down carbohydrates and store them as fat. And other research corresponds to this latest finding. According to Philpott, a study of more than 11,000 kids found that the group prescribed antibiotics before the age of six months “had a 22 percent higher chance of being overweight at age three” than those who did not take antibiotics.

Philpott questions whether the antibiotics used in livestock feed could have a weight-gaining effect when consumed by humans, and in his research finds that the safety limits for antibiotics in food set by the FDA are dependent on research funded and conducted by the ag industry. While the research doesn’t yet exist on whether or not antibiotic-laced meat is altering human gut bacteria, Phipott found a study that found traces of antibiotics in meat strong enough to slow the growth of certain bacteria.

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Image: Wisconsin Department of Natural Resources