Early exposure to microbes will give children the best immune start to life, insist two microbiologists who’ve written thought-provoking new book, Let Them Eat Dirt. Professor Brett Finlay and Dr Marie-Claire Arrieta insist there is undeniable evidence that early exposure to microbes is beneficial to children’s wellbeing.
The scientists have written the book to explain their conviction that microbiota (the microbes that live in and on humans) are great for our health. “In our quest to clean up our world and get rid of infectious diseases, we have become too clean and we need to rethink our quest for cleanliness,” stresses Prof Finlay.
“We don’t directly advocate ‘eating dirt’, but we now realise kids, especially early in life, depend on abundant microbial exposure that’s needed to develop normally. Without this exposure, they are at a much-increased risk for the ‘Western’ diseases such as allergies, asthma, inflammatory bowel disease, obesity, diabetes, etc. later in life.”
Prof Finlay and Dr Arrieta point out that of the thousands of microbe species, only about 100 are known to cause human disease: “The vast majority do not cause any problems and, in fact, seem to come with serious benefits.”
One well-known theory, the ‘hygiene hypothesis’, suggests a lack of exposure to bacteria and parasites during childhood may be the cause of a rapid increase in allergies, as it prevents proper development of the immune system. Prof Finlay and Dr Arrieta believe the huge rise in the number of children with food allergies is because youngsters are “microbially deprived”.
They say there is now plenty of solid evidence suggesting the hygiene hypothesis helps explain the development of many diseases as well as allergies. The pair points out that as well as increased cleanliness reducing childhood exposure to microbes, there are other reasons for the reduction — primarily the “use, overuse and abuse” of antibiotics.
You don’t get much muckier than on a farm, but the book explains that children raised on farms have certain immune advantages over children brought up in cities. However, Dr Arrieta says there are many things city parents can do to help their kids get ‘farm perks’: “While the odd field trip to a farm will probably not do a lot, unnecessary use of antibiotics, excess use of antibacterial hand cleansers, not having a pet, etc, are all ways of decreasing microbial exposures that can be changed. Letting a kid play in the dirt isn’t necessarily bad - this is how human children evolved, and living in an extremely clean environment is not how we have evolved as a species.”