'Hygiene hypothesis' busted?

Cleanliness is not a threat to children’s immune systems or the reason behind rising allergies across the globe, scientists at University College London (UCL) have argued.

The research, published in the Journal of Allergy and Clinical Immunology, further debunks the ‘hygiene hypothesis’, which suggests human immune systems are being compromised by sterile surroundings and that it is better to be exposed to bacteria so that, children especially, can build up immune defences.

The team highlighted four significant reasons that debunk the theory:

1. Micro-organisms found in the modern home are typically not ones that are needed for immunity
2. Vaccines protect from infection but also strengthen immune systems, reducing the risk of death through exposure to pathogens
3. Micro-organisms of natural green environments are important for health, and domestic cleaning and hygiene have no impact on exposure to the natural environment
4. Associations found between cleaning the home and health problems, including allergies, are not linked to the removal of organisms but the lungs being exposed to cleaning products that can cause damage that in turn leads to allergic responses.

“This idea that we are too clean for our own good has been causing chaos, and people are taking it too seriously,” said Professor Graham Rook, professor of medical microbiology at UCL. “Cleaning the home is good, and personal cleanliness is good, but… to prevent spread of infection it needs to be targeted to hands and surfaces most often involved in infection transmission. 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,” he added. “These exposures are not in conflict with intelligently targeted hygiene or cleaning.”

Read more on tackling misconceptions about hygiene here.