The Hygiene Hypothesis And Mental Health

The hygiene hypothesis states that exposure to germs helps strengthen our immune systems, building resistance along the way. Recently released research from the University of Colorado Boulder found that these same exposures are important for mental health, too.

Christopher Lowry, the study’s co-author, said there is already ample evidence, which documents “that exposure to pets and rural environments during development is beneficial in terms of reducing risk of asthma and allergies later in life”. For the first time, he added, the study furthers that link, and has established an effect on mental health in humans.

Researchers examined 40 healthy German males between 20 and 40 years old. Participants gave speeches and attempted math problems before their blood and saliva were tested. Half of participants grew up in cities, the other half on farms. They found that males who grew up in urban environments had heightened immune responses.

Researchers also found that urban-raised participants felt less stressed than their rural counterparts.

“This exaggerated inflammatory response is like a sleeping giant that they are completely unaware of,” Lowry said.

Past studies have shown that exaggerated inflammatory responses are linked to higher risks of depression and post-traumatic stress disorder (PTSD) later in life. Research has also shown that immune responses to stress are developed in childhood, and are “strongly influenced by our microbial environment”, the article added. “Humans are exposed to far fewer microorganisms in the city, which is now home to more than half of the global population.”

To this, researchers suggest spending time outdoors, getting a pet and consuming probiotics!