Moms can relax. Dirty little children aren’t such a bad thing.
Exposure to germs as a kid seems to be helpful, while living in an environment that’s squeaky clean seems to pose risks for some illnesses. Still, nobody knew precisely why. But now some scientists say they think they’ve figured out the details of the “hygiene hypothesis.”
They found that microbes in the gut keep a rare part of the immune system reined in. No microbes, and the immune cells go crazy in the lungs and intestines, increasing the risk of asthma and colitis. Add in the microbes, and cells in question, invariant natural killer T cells, retreat.
Aside from toxic waste, getting grimy and being exposed to a variety of germs in the environment can actually improve immunity.
