More evidence suggests exposure to germs can build healthy immune systems in kids

If you live by the philosophy that a little dirt and dust never hurt anybody, science has once again backed you up.

Researchers at the University of Ulm in Germany and the University of Colorado-Boulder conducted a study which revealed that kids who grow up in a rural environment and are exposed to dirt, dust and animals end up with more stress-resilient immune systems and may also be at a lower risk for mental illness than those who live in an urban environment without pets.

The study, published in the Proceedings of the National Academy of Sciences of the United States of America, is just the latest in a growing body of research that supports the so-called “hygiene hypothesis,” which suggests that a lack of exposure to germs and bacteria leads to health problems.

The study involved 40 healthy German men between the ages of 20 and 40 — half of whom had grown up in a large city without pets while the other half grew up on a farm with farm animals — and subjected them to stressful situations, testing their blood and saliva before, during and after the experience.

The participants who had grown up in an urban environment “had a much-exaggerated induction of the inflammatory immune response to the stressor,” Christopher Lowry, co-author of the study, told Science Daily.

In addition to building up strong immune systems, the study’s authors suggest that exposure to germs might even be helpful to our mental health later in life.

“If you are not exposed to these types of organisms, then your immune system doesn’t develop a balance between inflammatory and anti-inflammatory forces, and you can develop a chronic, low-grade inflammation and exaggerated immune reactivity that makes you vulnerable to allergy, autoimmune disease and, we propose, psychiatric disorders,” Lowry said.

The connection to mental health lies is a protein found in blood called IL-6.

“Depressed patients have an exaggerated IL-6 response to this test,” Lowry explained to Newsweek. “If a child has elevated IL-6 levels in childhood they are also more likely to have symptoms of depression later in life.”

More research is needed to definitely prove the connections posited, but for now it sounds like a great excuse to skip dusting for today and cuddle up with your dog!