Over the past 30 years obesity rates have soared. Most adults are overweight, as are 15% of grade school children. We all know the culprits: too little exercise, too many videogames and too many calories.
But what if there’s more to it than that?
Maybe the culprit is bacteria–or, rather, the lack of the right kind of bacteria. That’s the radical theory of Martin Blaser, chairman of the department of medicine at New York University Medical School and former president of the Infectious Disease Society of America. Blaser suspects that chronic antibiotic overuse could be making kids fatter by killing off healthy gut bacteria necessary for efficient digestion.
“I don’t think it’s due to Big Macs, and I don’t think it’s due to lack of exercise. Our ancestral microbes are disappearing,” says Blaser.
His theory is not as crazy as it may sound. In recent years a flood of new scientific findings has shown that the bacteria living inside us have a profound impact on our health–or lack thereof. Good bacteria living in the gut and elsewhere may protect us from obesity and diabetes, prevent asthma, help the immune system function properly, aid in the metabolism of common drugs like Tylenol, and even protect against throat cancer. Bacteria living on the skin appear to play a crucial role in warding off infections.
There are 100 trillion bacterial cells in the body, 10 times the number of human cells. They fit because a bacterium is one-thousandth the size of a typical human cell. A recent article in Nature predicted that within 10 years, doctors would treat stomach problems, asthma and other diseases by modifying the bacterial population inside patients, killing off bad species or helping good germs to flourish.
The bulk of our body’s tiniest citizens live in the intestine, where they help digest food. But bacteria also may play an important role in obesity. Ruth Ley, a Cornell researcher, has found that the mix of bacteria in the human gut differs dramatically depending on how much we eat. Obese people tend to have different gut bacteria than thin people, she found. While this doesn’t prove cause and effect, one possibility is that some people are prone to gaining weight because they have the wrong type of bacteria in their guts. Meanwhile, mice genetically engineered to get early onset diabetes no longer get it when researchers implant the right gut bacteria. …