Being clean and hygienic need not impair childhood immunity

Study published in the Journal of Allergy and Clinical Immunology - The theory that modern society is too clean, leading to defective immune systems in children, should be swept under the carpet, according to a new study by researchers at UCL and the London School of Hygiene & Tropical Medicine. In medicine, the 'hygiene hypothesis' states that early childhood exposure to particular microorganisms protects against allergic diseases by contributing to the development of the immune system. However, there is a pervading view (public narrative) that Western 21st century society is too hygienic, which means toddlers and children are likely to be less exposed to germs in early life and so become less resistant to allergies. In this paper, published in the  Journal of Allergy and Clinical Immunology , researchers point to four significant reasons which, they say, disprove this theory and conclude we are not "too clean for our own good".