Our obsession with being “clean” may come at a big price for our microbiome. A radically shifted lifestyle, from rural areas to cities, made us less used to be exposed to a diverse range of bacteria. We became accustomed to urban environments, preferably free from bacteria. We want to protect our children against germs and diseases, but are disinfected environments as healthy as we think? The hygiene hypothesis states that our modern sterile lifestyle confuses our immune system. Instead of protecting us from diseases, the immune system will respond the other way around, causing all sorts of allergic reactions and autoimmune diseases.


In the 19th century, hay fever emerged among the upper classes of Britain. Doctors noticed that allergies were rare among farmers, who were exposed to more pollen. In 1989, epidemiologist David Strachan found that allergies are less common in children from larger households, suggesting that coming into contact with microbes might protect against allergies. Strachan’s and other studies showed that they play a critical role in immunoregulation and in inhibiting inappropriate immune responses.

This phenomenon was described as the “old friends hypothesis” and suggests that early and regular exposure to harmless microorganisms — the “old friends” — train the immune system to react appropriately to threats. Thanks to modern hygiene and sanitation, we have seen lower rates of many diseases and health problems.


Today, we have antibacterial soap, antibacterial spray, antibacterial cleaning wipes and a myriad of disinfecting cleaning products. Kids are growing up in clean, disinfected, sterile environments. We go to great lengths to make sure we are protected from germs. At the same time, we have rising rates of allergies, autoimmune problems and gut related disorders, especially in children. This is even affecting our animal companions, influenced by our clean diet and hygiene measure, they to have more auto-immune and microbiome-linked disorders.

As a result, due to increased hygiene (since the 1950’s) and misuse of antibiotics, our immune system got out of balance. This has led to a dramatic increase in auto-immune diseases and antibiotic resistance and has negatively impacted our skin health.

The conflict between cleanliness and exposure can leave us feeling confused. How can we find the middle ground?

Hygiene hypothesis 2_RS



The human immune system, that is designed to fight off infections and harmful agents such as bacteria and viruses, starts building after birth. Before that, the mother protects the baby when the baby is still inside the mother’s womb. As soon as the baby is born, the immune system has to start working for itself and learn how to fight off infections and bacteria on its own. The more germs in every day life it is exposed to, the stronger it gets.

The change in lifestyle, from farm to city, made us less exposed to microbes in modern life. Children who grow up in over-sterilized environments don’t get the chance to properly challenge their immune systems. The immune system then can start attacking the body’s own tissues causing asthma or other autoimmune diseases. The immune system can also attack harmless particles in our environment causing allergic reactions such as eczema or hay fever. This happens in all developed countries where sterile environments don’t pose an effective challenge to a growing immune system.


Rolling around in the dirt and having an unclean lifestyle is not the way we want to spend our lives. We still want to protect ourselves from harmful bacteria and viruses, but we shouldn’t exaggerate. Walking barefoot on grass or exposure to bacteria of your close family members is not a bad thing. In fact, children who live with animals or who start attending day care early in life are exposed to a variety of microbes and are less likely to suffer from asthma and allergies.

Hygiene hypothesis 3_RS

But the most important lifestyle change should be focused on our view on healthcare. Numerous scientific researches found that our skin microbiome is key to our health to overcome this disruption in the long run. Your conscious choice in skincare, using microbiome friendly products, allows your immune system to welcome new “old friends”. In turn, your bacteria have the best toolset to keep you healthy and your skin microbiome diverse. YUN developed all products with the healthy microbiome as a top priority, by suing microbiome safe ingredients to strenghten and by adding live bacteria to fight bad bacteria that cause disease.

To sum up, the way to go is to find a balance in what our immune system needs: not too many microbes but also not too little.

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