Getting Dirty Early Might Help You Live Longer

Letting your kids play in the dirt may be better for them than it might initially seem. Recent research shows that early exposure to infectious microbes may be linked to how we regulate inflammation associated with diseases brought by aging such as diabetes, dementia, and cardiovascular disease.

The study looked at the C-reactive protein (CRP). CRP is an important protein in helping us fight off infectious diseases and whose elevated levels mean a response to inflammation. When CRP is constantly produced, however, it is linked with inflammation that brings on other diseases.

"In other words, CRP goes up when you need it, but it is almost undetectable when you don't, after the infection resolves," said Thomas W. McDade, professor of anthropology at Northwestern and faculty fellow at the university's Institute for Policy Research. "This is a pretty remarkable finding, and very different from prior research in the U.S., where lots of people tend to have chronically elevated CRP, probably putting them at higher risk for chronic disease."

Previous research conducted by McDade in the Philippines showed that higher levels of exposure to microbes and bactera during infancy correlated with lower levels of CRP in adulthood.

When looking at adults in the Ecuadorian Amazon, McDade did not find a single case of chronic low-grade inflammation that could bring about age-related diseases. However, he did state that people are still dying of cardiovascular diseases, but not from ones brought on by inflammation.

"In my mind the study underscores the value of an ecological approach to research on the immune system, and it may have significant implications for our understanding of the links between inflammation and chronic disease," McDade said. "This may be particularly important since nearly three-quarters of all deaths due to cardiovascular disease globally now occur in low- and middle-income nations like the Philippines and Ecuador."

Infectious diseases have been a part of human history, and it is only in the past couple hundred years that we have begun sterilizing our environments so much and limiting our exposure to microbes. The discovery of bacteria and viruses as disease-causing pathogens played a huge role in this.

"It builds on research on chronic inflammation and cardiovascular disease in the U.S. and other affluent, industrialized settings and suggests that patterns seen here may not apply globally," said McDade. "It also suggests that the levels of chronic inflammation we see in the U.S. are not universal, and may be a product of epidemiological transitions that have lowered our level of exposure to infectious microbes.