Our obsession with clean
Why it’s making us less healthy
Jan 25, 2026
In the 70s and 80s I was a microbiologist and chief lab technologist in the local hospital
Throughout eons of evolution, from the lowly earthworm to the present, we’ve had a close association with dirt – which is home to millions of bacteria, moulds, etc. (Earthworms are essential for turning that dirt into the soil that sustains the plants which feed us.) Up until a few centuries ago, we didn’t know any of this but those microorganisms were and are essential to our existence. As with all animals cleanliness was not something that concerned us.
We didn’t have soap, we didn’t take showers … and we survived and multiplied.
(Archaeological research indicates that some early soaps appeared about 3,000 years ago but there is little evidence that it was in common use until relatively recently.)
We learned that there were things we shouldn’t do. People realized that if you got a deep cut and it got dirty, there was a chance that you could get lockjaw (tetanus – caused by Clostridium tetani). Cleaning a wound was important – even if you didn’t have soap. We realized that if you were bitten by an animal that was frothing at the mouth that you might get rabies yourself. Or that if you associated with people who were obviously sick, there was good chance you might get sick yourself. You can call it instinct or you can say it was things passed on by our parents. Perhaps it was just common sense.
Avoidance was and is the best medicine. We survived and multiplied.
When people began living in cities, diseases spread more rapidly. When the plague (Yersinia pestis) came to Europe it killed half of the population. But avoidance and common sense saved the other half.
The Industrial Revolution in the mid 1800s brought thousands of people to vermin infested slums. Cities were dirty and people got sick – many died. But it wasn’t the dirt per se that killed them – it was the rats spreading diseases – coupled with poor nutrition which left people vulnerable.
The late 1800s brought the discovery of bacteria and we learned that they could be killed. This prompted a boom of private ‘entrepreneurs’ marketing a cacophony of ‘disinfectants’ promising health by killing all those bugs. But it didn’t work out that way – most of the bugs we were killing were part of our own health. Bacteria have evolved alongside us and throughout that evolution many of them adopted protective roles inhibiting or killing harmful organisms.
And now we are bombarded daily with ads for the ‘clean’ industry – soaps, detergents, disinfectants, anti this and anti that. In 2022 the average American family spent more than $85 on soaps and detergents – it’s a (more than) $11 billion industry.
And we are less healthy.
You see, all through evolution we developed a protective shield. Our skin has a combination of oils and resident organisms which fend off potentially harmful organisms – so when we wash all that off in the shower it leaves us more vulnerable. Showering every day has become the norm especially among younger people. Not only does that leave us more susceptible to infections but we are washing billions of dollars in cleaning agents down the drain where it destroys the finely tuned ecosystems of our waterways.
The natural bacteria in our mouths protect our teeth and yet we brush it all away and then kill what’s left with mouthwashes. And send more chemicals into our lakes and streams.
Our digestive tracts contain by far the largest and most important parts of our microbiome. Our guts contain hundreds of trillions of microorganisms (bacteria, fungi, archaea, viruses and even a few helminths) belonging to up to a thousand different species.
The more we research the more we know about their relation to human diseases – not as causes but as protectors. Up to the 1970s the standard treatment for gastrointestinal diseases (Salmonella, E. coli, etc) was antibiotics, until doctors realized that this largely prolonged the infection because it killed off the good bacteria which maintained the homeostasis.
Certain chronic bowel diseases such as IBS (irritated bowel syndrome) and ulcerated colitis have been linked to autoimmune conditions – which may be true – but they are being treated successfully by “fecal microbiota transplantation, a process involving the transfer of stool from a healthy donor into the gastrointestinal tract of a patient” which suggests a different etiology
The human immune system creates cytokines that can drive the immune system to produce inflammation in order to protect itself, and that can tamp down the immune response to maintain homeostasis and allow healing after insult or injury. Different bacterial species that appear in gut flora have been shown to be able to drive the immune system to create cytokines selectively; for example Bacteroides fragilis and some Clostridia species appear to drive an anti-inflammatory response, while some segmented filamentous bacteria drive the production of inflammatory cytokines. Gut flora can also regulate the production of antibodies by the immune system.
Gut bacteria have been found in the last 10 years or so to have a direct connection to your brain and they influence your mood and mental health.
So, ignore all the advertising and start using common sense like our great grandparents did. That piece of bread that fell on the floor is still edible – brush off any obvious dirt and eat it. Don’t be paranoid about mould – many people (including myself) have allergies to moulds but apart from that, most are harmless – cut away the mouldy part and eat the rest – use your common sense.
Ignore expiry and best before dates. Virtually all food will have some bacteria in or on them … and they grow. Expiry dates are based on the assumption that the handling of food in its path from farm to you has been less than ideal at some point – such as sitting on a loading dock for a couple of hours. If it was handled well it might be good for many more days. Use your judgment – if it looks OK, smell it, taste it, eat it. Even if it smells or tastes “off’“ it is likely still OK – all cheeses and yogurts are produced by bacteria. Beers and wines are made by yeasts (fungi).
Our immune system is part of our defences. All through evolution which we spent in close contact with dirt, we were training our immune system to differentiate between good stuff and bad. We got sick, we recovered and our system shrugged off subsequent infections.
About 150 years ago we got one very important thing right. Louis Pasteur created the first vaccine. By challenging our immune systems with weakened versions of harmful organisms, we have been able to avoid infections from the real thing. I suspect many of the people who regard immunizations as a hoax are the same people who use a lot of cleaning supplies thinking they are protecting themselves.
Many parents these days try to keep their kids in a sterile bubble, but playing in the dirt is how our bodies trained themselves to cope with a world in which all those microdenizens outnumber us billions to one.
Both of my parents grew up on pioneer farms but I was born and grew up in Toronto. We had a sandbox in the back yard and we spent summers in Muskoka. In the early years our cottage had no electricity or running water. Dirt was part of life. As a result I have a robust immune system. Taking microbiology in university and working in a hospital lab provided the context.
Don’t fight it. Embrace your microbiome.
