Our obsession with ‘cleanliness’ can come at a high cost. With urbanization and moving away from rural life, we are increasingly less exposed to a diversity of microorganisms. We have become accustomed to sterile, bacteria-free environments. We protect children from germs — but is such an environment truly healthy?
The hygiene hypothesis suggests that today’s overly sterile lifestyle weakens our immune system. Instead of protecting us from diseases, it begins to react improperly, triggering allergies and autoimmune disorders.
In the 19th century, it was noticed that hay fever was more common among the upper social classes in Great Britain. Doctors observed that allergies were less frequent among farmers, who were more regularly exposed to pollen. In 1989, epidemiologist David Strachan showed that children from larger families developed allergies less often — suggesting that exposure to microorganisms may protect against allergy development.
This phenomenon came to be known as the ‘old friends hypothesis’ — the idea that early and regular exposure to harmless microorganisms ‘teaches’ the immune system how to respond correctly to threats. Modern hygiene has reduced the incidence of many infectious diseases, but at the same time deprived us of this natural immunological education.
Today we have access to antibacterial soaps, sprays, wipes, and disinfectants. Children grow up in sterile conditions, yet we observe rising rates of allergies, autoimmune diseases, and gut disorders. Interestingly, lifestyle and diet contribute to similar changes in pets.
The rise in hygiene since the 1950s, along with the overuse of antibiotics, has led to an imbalance in the immune system. The result is an increase in autoimmune diseases, antibiotic resistance, and a deterioration in skin health.
The conflict between cleanliness and the need for exposure to microorganisms is confusing. How do we find the golden middle ground?
The human immune system, designed to fight infections and harmful factors such as bacteria and viruses, begins to develop after birth. Before that, the mother’s body protects the child in the womb. After birth, the child’s immune system must start functioning independently and learn to recognize and combat pathogenic microorganisms. The greater the exposure to microbes in daily life, the stronger the immune system becomes.
The shift in lifestyle — from rural to urban — has resulted in decreased exposure to microorganisms in the modern world. Children raised in overly sterile environments do not have the opportunity to properly ‘train’ their immune systems. As a result, the immune system may begin attacking the body’s own tissues, leading to the development of asthma or other autoimmune diseases. It may also react to harmless particles in the environment, triggering allergic reactions such as eczema or hay fever. This phenomenon is observed in all developed countries, where a sterile environment does not sufficiently challenge the maturing immune system.
Rolling around in dirt and living in filth is not the goal. We still want to protect ourselves from harmful pathogens, but we shouldn’t go to extremes. Walking barefoot on grass or being exposed to the bacteria of other household members is not a bad thing. Children who live with pets or start attending daycare early are exposed to a wider variety of microorganisms and are less likely to develop asthma and allergies.
The most important lifestyle change should be our approach to health protection. Numerous scientific studies indicate that the skin microbiome plays a key role in maintaining health and is essential for preventing its disturbances in the long term. Conscious skincare choices — using microbiome-friendly products — allow the immune system to once again ‘invite old friends.’ This gives the bacteria living on our skin the right tools to protect health and maintain the skin’s microbial diversity. The YUN brand has developed its products by putting a healthy microbiome first — using microbiome-safe ingredients and adding live bacteria that support our natural defense system against factors that cause skin problems.
In summary, the key to healthy immune development is finding balance — not too much, and not too little exposure to microorganisms.
