Children should be allowed to get dirty because it boosts their skin’s ability to heal, according to US scientists.
Researchers from the School of Medicine at University of California, San Diego, found being too clean can impair the skin's ability to heal.
Normal bacteria living on the skin trigger a pathway that can dampen down overactive immune responses, which can lead to rashes or cause cuts and bruises that become swollen and painful because they become inflamed.
Their findings, published in the online edition of Nature Medicine, provide an explanation for the "hygiene hypothesis", that exposure to germs during early childhood primes the body against allergies. The hygiene hypothesis suggests that an obsession with cleanliness is to blame for a massive rise in the number of people afflicted by allergies such as eczema and hayfever.
The team found that staphylococci, naturally present on the skin, can reduce inflammation after injury, when they are present on the skin's surface.
By studying mouse and human cells, the team identified a mechanism by which a product of staphylococci (staphylococcal lipoteichoic acid) prevents inflammation.
Staphylococcal lipoteichoic acid acts on keratinocytes, the primary cell type found in the epidermis, stopping them from mounting an aggressive inflammatory response.
