Could growing up with pets be the secret to health and happiness?

According to a new study from the University of Ulm and CU Boulder, children raised in the countryside surrounded by animals are at less risk of developing a mental illness than their pet-free city-dwelling counterparts. 

Why? Because being in nature exposes them to bacteria-laden dust that helps strengthen their immune systems and better enables them to deal with stress.

“It has already been very well documented that exposure to pets and rural environments during development is beneficial in terms of reducing risk of asthma and allergies later in life,” professor of integrative physiology at CU Boulder Christopher Lowry and they study’s author told Daily Mail.

“This study moves the conversation forward by showing for the first time in humans that these same exposures are likely to be important for mental health.”

40 German men aged 20 to 40-years-old participated in the study. Half were raised on a farm, while the rest were city folk. To test their stress levels, they were asked to do two things: give a speech in front of a group of people and solve a math equation with limited time to do so. The men also provided blood and saliva samples so the researchers could monitor their immune response.

The results were clear: those who grew up in urban areas had much higher levels of peripheral blood mononuclear cells (PBMCs).

“People who grew up in an urban environment had a much-exaggerated induction of the inflammatory immune response to the stressor, and it persisted throughout the two-hour period,” Professor Lowry explained in the report. 

“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 chronic, low-grade inflammation and exaggerated immune reactivity that makes you vulnerable to allergy, autoimmune disease and, we, propose, psychiatric disorders.”

This article was originally published on Women's Health