Being clean and hygienic does not lead to children having poorer immune systems, a new UK study has claimed.
Researchers at UCL and the London School of Hygiene & Tropical Medicine say it is time to put to bed the view that western 21st century society is too hygienic, which has led to toddlers and children being less likely to be exposed to germs in early life and therefore less resistant to allergies.
Lead author Emeritus Professor of Medical Microbiology Graham Rook, of UCL Infection & Immunity, said: “Exposure to microorganisms in early life is essential for the ‘education’ of the immune and metabolic systems.
“Organisms that populate our guts, skin and airways also play an important role in maintaining our health right into old age: so, throughout life we need exposure to these beneficial microorganisms, derived mostly from our mothers, other family members and the natural environment.
“But for more than 20 years there has been a public narrative that hand and domestic hygiene practices, that are essential for stopping exposure to disease-causing pathogens, are also blocking exposure to the beneficial organisms.
“In this paper, we set out to reconcile the apparent conflict between the need for cleaning and hygiene to keep us free of pathogens, and the need for microbial inputs to populate our guts and set up our immune and metabolic systems.”
Writing in the Journal of Allergy and Clinical Immunology, the authors say their review of evidence showed that the microorganisms found in a modern home are, to a significant degree, not the ones that we need for immunity. It also points out that vaccines both protect us from the infection they target and do a lot more to strengthen our immune systems, so we do not need to risk death by being exposed to the pathogens.
There is now solid evidence that the microorganisms of the natural green environment are particularly important for our health – and that domestic cleaning and hygiene have no bearing on our exposure to the natural environment – and that recent research shows that when epidemiologists find an association between cleaning the home and health problems such as allergies, this is often caused by exposure of the lungs to cleaning products that cause a type of damage that encourages the development of allergic responses.
“So, cleaning the home is good, and personal cleanliness is good, but, as explained in some detail in the paper, to prevent spread of infection it needs to be targeted to hands and surfaces most often involved in infection transmission,” said Prof Rook.
“By targeting our cleaning practices, we also limit direct exposure of children to cleaning agents. Exposure to our mothers, family members, the natural environment, and vaccines can provide all the microbial inputs that we need. These exposures are not in conflict with intelligently targeted hygiene or cleaning.”
Rook G, Bloomfield S. Microbial exposures that establish immunoregulation are compatible with Targeted Hygiene. Journal of Allergy and Clinical Immunology 6 July 2021; doi: 10.1016/j.jaci.2021.05.008.
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