Our Homes Are 'Too Clean,' Should Be Seeded With Germs, Says Researcher

Introducing "good bacteria" into your home may help prevent your children from developing childhood illnesses like asthma, a researcher said.

Homes have become exceptionally clean these days, thanks to modern cleaning, which may leave children bereft of exposure to bacteria and other germs that are important in the development of a healthy immune system.

Using a household probiotic may help children get exposed to microbes that will allow their immune systems to build up defenses, hopefully preventing them from developing allergies and asthma, according to a new book titled Inside OUT: Human Health and the Air-Conditioning Era and written by Elizabeth McCormick.

McCormick is an assistant professor of architecture and building technology at the University of North Carolina' at Charlotte's School of Architecture and specializes in healthy and climatically sensitive building-design strategies.

This is especially important considering that U.S. citizens spend up to 90 percent of their time inside, further limiting our exposure to germs.

"Advertisements for hand soaps and detergents, for example, underscored the fear of germs, while advertisements for prescription drugs also emphasized visual representations of germs," McCormick said in a statement. "Ultimately, the realization that diseases could be spread through human trans­mission, not environmental conditions, induced a culture of excessive cleanli­ness and urban germaphobia."

A theory called the hygiene hypothesis suggests that a lack of exposure to infectious agents and certain microbes during childhood may lead to an increased risk of autoimmune diseases and allergies later in life. The idea behind the hygiene hypothesis is that early exposure to bacteria, viruses and other microbes helps to train the immune system and regulate its responses.

Without this exposure, the immune system may become overly sensitive and prone to reacting to harmless substances, such as pollen or certain foods, leading to allergies. Additionally, the hypothesis suggests that certain infections during childhood may help suppress the development of autoimmune diseases by keeping the immune system appropriately balanced.

"The basic concept is that the lifestyles of many people have become excessively clean," Byram Bridle, an associate professor of viral immunology at Canada's University of Guelph, told Newsweek. "At its core, the idea is that exposure to safe molecules and microorganisms in our environment promotes the development of immunological tolerance, especially during early childhood."

Bridle went on: "The human immune system learns to differentiate things that are dangerous from things that are safe, and it gets programmed to respond to the former and ignore the latter. Most of this tolerization of the immune system occurs between birth and approximately 6 years of age, although the immune system is not fully mature until well into the teens.

"Reduced exposure to natural environmental particulates and microorganisms during this critical period of maturation of the immune system can result in dysregulation, an inability for the immune system to properly control itself. This is thought to result in a higher incidence of hypersensitivities like allergies and asthma, as well as autoimmune diseases in children raised in overly clean environments," Bridle said.

He said that scientific evidence for this comes from studies that have noted elevated rates of allergies, asthma and autoimmune diseases in children raised in developed countries, compared with those growing up in developing ones.

Excessively cleaning the home means that children aren't exposed enough to microbes and therefore may be more at risk of developing allergies.

This may be exacerbated by the design of modern homes, which don't allow effective ventilation of outdoor air—and therefore outdoor microbes and allergens—into the house.

McCormick said, "In true antibiotic fashion, the dis­course surrounding the modern approach to 'healthy' buildings has revolved around the total elimination of microbial communities, which eliminates organ­isms that are both non-pathogenic and necessary for healthy and robust immune function. Certain levels of microbial exposure are fundamental to human health."

She continued: "This microbial network is an inevitable and essential component of both human and non-human life; however, buildings often neglect this notion, instead opting for sterile, antiseptic interior spaces."

McCormick suggests that one method to address this problem could be to "seed" a house with probiotic bacteria in some way, to expose children to the appropriate level of microbes. This may include getting a dog or having indoor plants.

Vasso Apostolopoulos, a professor of immunology at Australia's Victoria University, told Newsweek: "While maintaining proper hygiene practices is essential to prevent the spread of infectious diseases, there is also a need for microbial exposure for the development of a healthy immune system, especially in early childhood. There must be a balance between cleanliness and microbial exposure, such as promoting outdoor play, encouraging contact with pets and avoiding unnecessary antibiotic use, [which] may help mitigate the rising prevalence of childhood illnesses like asthma and allergies."

She continued: "The idea of intentionally introducing 'healthy germs' or 'probiotics' into indoor environments to improve human health is an intriguing concept. There is research which suggests that the diversity and composition of microbial communities in our surroundings can have significant impacts on our health and well-being.

"We and others have shown that probiotics can have beneficial effects on the human immune system and confer digestive and health benefits. Extending this concept to indoor environments, where we spend the majority of our time, could offer new avenues for promoting health and preventing illness," Apostolopoulos said.

However, she said that such implementation requires careful consideration and further research.

Other solutions suggested by McCormick include not overcleaning and improving ventilation in buildings.

Additionally, improved ventilation can help to manage the levels of indoor pollutants, which are harmful to the body. One study found that children who grew up around gas stoves had a 42 percent increased risk of childhood asthma and a 24 percent higher risk of lifetime asthma.

"It's possible, and even likely, that the air in the middle of a busy intersection might actually be cleaner than the air in your living room right now," McCormick said. "However, most Americans still perceive the risks of outdoor air pollution as being substantially higher than the threat of indoor air, even though dangers posed by long-term exposure to unhealthy indoor air have become more apparent in recent years, par­ticularly for people who suffer from allergies and asthma, as well as children and the elderly."

Allergies are increasing across the globe, she said, but more so in the developed world because of chemical exposures in low-quality indoor air.

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