One hundred trillion cells bearing 3 million different genes-that's the roster of microbes that live inside your body. They're not just passengers; if animal studies hold up, these unseen multitudes profoundly affect the body's response to the environment, illness, and medical treatment. This year, researchers started pinpointing specific ways in which the microbiome promotes health and disease. In 2008, nearly 300,000 infants in China got kidney stones from milk formula tainted with melamine, a plastics additive that was used illegally to bulk up the formula's apparent protein content. This year, scientists found that a bacterium may be to blame. A study showed that rats exposed to melamine developed fewer kidney stones when they were given antibiotics.
展开▼