Can a clean environment cause allergies and asthma?A new study refutes the hygiene hypothesis


In the past 50 years, the ability to keep houses clean and protect people from germs has become more advanced. But will the use of antibacterial soap and various cleaning chemicals cause them allergies and asthma?

Population-based studies consistently show that the prevalence of allergies and asthma in urban environments is higher than in farms and other rural environments. Air pollution caused by industrialization is certainly part of the problem, but epidemiologists want to know whether other factors in modern society also play a role.

In 1989, British epidemiologist David Strachan developed “Hygiene Hypothesis” — The idea that exposure to “good” microorganisms in early childhood can boost the immune system and prevent allergies and asthma. This theory shows that modern society is too hygienic in terms of personal hygiene and household cleaning, preventing children from contacting the microbiota that is beneficial to the immune system.

But new research, published in Journal of Allergy and Clinical Immunology, Show that the theory is not necessarily correct.

“Exposure to microorganisms early in life is essential for the’education’ of the immune and metabolic systems,” Say Graham Rook, Professor of Medical Microbiology, University College London. “The organisms that grow in our intestines, skin and respiratory tract also play an important role in maintaining our health until old age. Therefore, we need to be exposed to these beneficial microorganisms throughout our lives. These microorganisms mainly come from our mothers and other family members. And natural environment.

“But for more than 20 years, there has been a public statement that hand and household hygiene practices are essential to prevent contact with pathogenic pathogens, but also prevent contact with beneficial organisms.”

After reviewing the available data, Rook and his team determined four reasons why the statement was incorrect:

1. In most cases, the microorganisms found in the home are not those required for immunity.

2. Vaccines help strengthen the immune system, so people do not need to be exposed to potentially dangerous bacteria and viruses to build immunity.

3. The microorganisms that people come into contact with in the womb, family members, and the environment contribute to the development of the immune system—— Not those found on the surface of the home.

4. Excessive use of chemical cleaning products will infiltrate the lungs and increase the risk of allergies and asthma, which is even more worrying.

according to Mayo Clinic, Exposure of pregnant women to infectious bacteria or other substances (such as vaccines) may help strengthen the baby’s immune system and the development of the intestinal microbiome.

John Lynch, associate professor of microbiology at the University of Washington, was not involved in this study. Say The “hygiene hypothesis” is problematic because it does not tell the complete story.

Lynch said it is important not to associate cleanliness with more diseases, because good hygiene can protect people from dangerous pathogens, including the pathogens that cause COVID-19. In addition, modern technology makes it easier to diagnose asthma and allergies. This is why the prevalence is higher in developed countries.

However, he warned against over-disinfecting the house. Not only are people unable to build a healthy microbiome in the body, but they also increase the risk of antibiotic-resistant bacteria.

“When you talk about the hygiene hypothesis, the focus of the debate is that less hygiene should be concerned, and more attention should be paid to obtaining the correct microbiota,” he added. “I like to think about it this way: if you have a sick person around you, or your children are rolling around on the restaurant floor, washing your hands is important, but if they are just playing outside, washing their hands is not that important. Park.”



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