Could you be healthier by being a little less hygienic?
If youʼd been a patient of acclaimed 18th century English physician Dr. John Mudge and had visited him with a cough, the chances are that youʼd have found yourself sucking air into your mouth via one of his ingenious “inhalers”.
Now although I say youʼd be sucking in air, Dr. Mudge was in fact a big fan of poppyseed-derived pharmaceuticals.
And his favored prescription for a cough was actually opium vapor.
Today of course, youʼre more likely to use an inhaler if you suffer from asthma.
Itʼs a rapidly widening condition. In 1980, less than 1 in 30 U.S. adults had asthma. Nowadays the figure is more like 1 in 12.
Asthma was already starting to become more prevalent by 1989, and it prompted an epidemiologist named Professor David Strachan at the University of London to wonder why.
Finding an inverse relationship between family size and the incidence of atopic disorders (atopic disorders are allergic conditions such as asthma and hay fever) he formulated a principle he called the “Hygiene Hypothesis”.
Put simply, he said that if you have more brothers and sisters, youʼre more likely to be exposed to a wider variety and number of germs, meaning you’ll develop a stronger immune system.
Strachan also suggested that improved household amenities and higher standards of personal cleanliness reduced exposure to the kinds of microbes which build immunity.
Strachanʼs hygiene hypothesis was questioned by many, and in fact even he later admitted that it “owed more to an alliterative tendency than to an aspiration to claim a new scientific paradigm”.
A rather awkward admission.
The thing is, he must have been at least on the right track as others have since gone on to re-craft his ideas in ways which may hold more water.
In 2003, Professor Graham Rook proposed the “Old Friends” hypothesis, which suggests that the microbes we actually need to be exposed to are those weʼve inherited from our primitive mammalian and human ancestors.
Since the majority of mammalian evolution took place in mud and rotting vegetation, Professor Rook argues that our immune systems can neither develop properly nor function without exposure to these ancient species.
Hmm… What do you think? Anyone for a mud and rotting vegetation spa break?
More recently Italian immunologist Dr. Paolo Matricardi (2010) has proposed that microbial variety is whatʼs most important.
He says diversity and turnover of bacterial species is a key factor in priming and regulating the immune system. A varied bacterial diet is what we should aim for, it seems, and plenty of it.
As atopic disorders affect more and more people, it’s interesting to note that two groups of children do significantly better than others in terms of avoiding these unpleasant, life-limiting conditions.
The first are those who grow up in a family with a dog.
Children who share their quarters with a canine are less likely to suffer from asthma, perhaps because of increased exposure to bacteria.
Interestingly itʼs an additive effect, so the more dogs (or cats) you have, the lower your risk of succumbing to asthma.
The other group of kids who do well?
The children of farmers. Again, itʼs believed that this is down to them being surrounded by diverse bacteria.
Overall, maybe it would pay us to be more mindful of whatʼs sometimes called biome depletion.
An overzealousness with the hand-sanitizer may do you more harm than good, particularly since itʼs now believed that reduced microbial exposure could be behind more than just the explosive growth of asthma and hay fever.
It might, for example, also be linked to Type 1 diabetes, multiple sclerosis and even some types of mental health condition, including depression.
So although I hesitate to say it, perhaps itʼs time to step away from the Purell.
And if you donʼt live on a farm, at least get out into the garden, naturally feeling free to frolic in some rotting vegetation.
Preferably with a dog.
Or even better, two.
Have a great week!
Asthma in the US
Can It Be Bad to Be Too Clean?: The Hygiene Hypothesis
Does childhood exposure to germs help prevent asthma?
National Surveillance for Asthma — United States
The ʻhygiene hypothesisʼ for autoimmune and allergic diseases: an update
The Hygiene Hypothesis: Are Cleanlier Lifestyles Causing More Allergies For Kids?
Family size, infection and atopy: the first decade of the “hygiene hypothesis”