Is Extreme Hygiene to Blame for Increase in Child Allergies?

These days it seems as though every other kid is allergic to something, which can make family wellness complicated. Even if your own child’s wellbeing isn’t affected by allergies, chances are that he or she will bring home a friend who is, and so you still have to deal with the problem. And the situation is only getting worse according to a recent study from the US Centres for Disease Control and Prevention (CDC), which found that allergies are on the rise. One in 20 children have food allergies today, which is a 50% increase from the 90s, while the number of children with skin allergies or eczema has risen by 69% to a whopping one in eight.


The odds are that you know a young child who has a food or skin allergy, which is why it’s now common practice for childcare settings and schools to ban potential allergens like tree nuts from all children’s lunches, in order to protect the wellness of these affected children. However, it’s difficult to determine whether these allergies have actually increased, or whether we’ve simply become more aware of what to look for, and so are just reporting more allergies in kids than we used to. Even the CDC study was based on parents’ self-reports of allergies in their children, and didn’t clarify whether or not the allergies were diagnosed by medical professionals, so some cases may have been misdiagnosed by hypersensitive parents.


Nonetheless, wellness experts seem to agree that recent decades have seen a dramatic increase in instances of both food allergies and hereditary atopic disorders such as eczema and asthma. This is at least evident in so-called developed countries, and herein lies a potential clue: we’re experiencing more allergies in the West because our culture is too good at controlling or eliminating exposure to microbes. As microbes are central to training our immune system to deal with allergens, excessive hygiene may be the cause of increased child allergies.


However, researchers like SF Bloomfield of the London School of Hygiene and Tropical Medicine warn against too simplistic a reading of this so called “hygiene hypothesis,” as broader, societal change is a more likely culprit. In their paper “Too clean, or not too clean,” Bloomfield et al argue, ‘The increase in allergic disorders does not correlate with the decrease in infection with pathogenic organisms, nor can it be explained by changes in domestic hygiene. A consensus is beginning to develop round the view that more fundamental changes in lifestyle have led to decreased exposure to certain microbial or other species, such as helminths, that are important for the development of immunoregulatory mechanisms.’


The researchers continue, ‘Although this review concludes that the relationship of the hypothesis to hygiene practice is not proven, it lends strong support to initiatives seeking to improve hygiene practice. It would however be helpful if the hypothesis were renamed, e.g. as the “microbial exposure” hypothesis, or “microbial deprivation” hypothesis, as proposed for instance by [Bengt] Bjorksten [professor emeritus at the Karolinska Institute in Sweden]. Avoiding the term “hygiene” would help focus attention on determining the true impact of microbes on atopic diseases, while minimising risks of discouraging good hygiene practice.’


This broader, societal reading of the “hygiene hypothesis” is seemingly backed up by studies, as, for example, kids are less likely to develop asthma if they grow up on farms. Moreover, if your child lives in a city, he or she is more likely to have a food allergy than kids who reside in the country. This is possibly because of increased exposure to air pollution in cities, and so we can see that it’s not as simple as blaming good hygiene.

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