Using data from a long-running study of children living in the Philippines, researchers at Northwestern University have found that children who live in germ-free environments are at increased risk of developing high rates of inflammation as adults—which can lead to illnesses such as heart disease.
The Filipino children studied were more likely to be exposed to domesticated animals and contract infectious diseases than American children. But as adults, the Filipinos studied had levels of C-reactive protein—a measure of inflammation—nearly 80 percent lower than American adults.
Thomas McDade, lead author of the study, told Agence France-Presse news service that exposure to microbes and bacteria early in life could actually help a human develop a stronger immune system in adulthood. "There's rapid brain growth early in life and there are lots of neurological connections being formed, and you need to engage with your environment in order to promote those connections," he said. "The immune system also needs engagement with its environment to drive its development, and without that environmental input, we're depriving it of a necessary source of information that it needs to promote its development."