"Too much cleanliness makes you vulnerable to germs!" Is this really true?

I’ve seen it claimed on more than a few posts on this very board, and many places IRL, that people who are particularly fussy about cleanliness, or fussy about their kids being clean, are making themselves/their kids more vulnerable to disease because by NOT being exposed to more germs, they do not form immunities. Mind you, I am not talking about living in plastic Bubble Boy houses; I mean just washing a lot, using hand sanitizer, stuff like that.

I’ve never seen any actual EVIDENCE that there’s any truth to this, I think it started with that George Carlin routine, and to be honest, it sounds really, really stupid to me. Even furious attention to hand-washing, kitchen cleanliness, and the use of ass gaskets won’t cut your germ exposure by ten percent, if five; germs are in the air, on everything you touch, on everything you eat.

But God knows I’ve been wrong a million times before.

So… is there actual scientific, objective evidence that being really clean can make you likelier to be sick?

I have also heard about this before and apparently there may be some truth in it. Here’s a link to a recent news story:


It’s not mechanical germ removal that’s the problem - hand-washing with normal soap, hand sanitizer with alcohol, etc, although you hear varying reports about kids and allergies. It’s anti-bacterial agents that breed resistant bacteria that people are really talking about.

To give a specific example, polio only became an epidemic disease in the 20th century because of improved sanitation. The polio virus is carried in feces, and prior to indoor plumbing, most children were exposed to various degrees through their childhood, and they built up an immunity to it. If they did get sick, it was relatively mild. Once indoor plumbing was a part of life, children - and adults - were no longer exposed to the polio virus constantly, so when someone did catch it, it was a much more serious illness.

Thankfully, though, in the case of polio, we have extremely effective vaccines. It’s not totally unlikely for there to be other illnesses similar to it.

This is how Asimov portrayed his ‘Spacers’.

Last week’s New Scientist had an article on this, but more related to the rise in auto-immune diseases than inducing vulnerability to infectious diseases. You’d need to subscibe to read the full article, but it starts:

Surely you don’t mean that exposing bacteria to a disinfectant Triclosan would give rise to a bacterial strain resistant to antibiotic medicine like Penicillin?

In microbiology lab, we sure didn’t have to be told twice to wash our hands with disinfectant soap…

I am tending to think like the OP these days. While I think there is perhaps something to the “too much cleanliness” hypothesis, it seems to have more to do with allergies. And even then, I’m confused. First of all, urban kids grow up in a germ-laden environment, due to the popularity of daycare, pre-school and other places with lots of kids in confined spaces, and are sick quite a bit of the time. I would guess that rural kids have less contact with other kids at an early age, and thus are exposed to less germs.

Many people believe that the immune system is like a muscle that gets better with use. It’s probably the opposite. If you are exposed to a lot of germs, you get sick more, not less. Ask any parent of a toddler. Immunity to specific viruses doesn’t seem to count for much in the long term, with the limited lifespan of antibodies, and the great variety and mutability of viruses out there.

Here is an interesting article in Nature, discussing the ‘helminth hypothesis’ - helminth (worms) infection roughly coincides with the increase in immune disorders.

The New Scientist article I referenced says more or less the opposite to this. The more exposure to bacteria of any sort - preferably harmless of course - during infancy the better. If left unchallenged the immune system can go on the rampage and triggers the auto-immune diseases and allergies we are seeing so much more of these days.

Whenever I try to figure out how to best treat my body, I go back to the beginning. In other words, our physiology evolved under certain conditions and a certain lifestyle, so therefore our immune system will function best if we replicate those conditions. So. It’s 500,000 years ago on the African savannah. Our immune system is our only defense against microbes, mainly those carried by the flesh of the animals killed for food, but also from infected wounds. Since the usage of antibacterial medications was low in those days, although I’m sure our ancestors knew of some herbs and plants that seemed to work well, the rate of mutation in the little buggers was lower. Which means that our immune system evolved to fight off The Usual Suspects, i.e. a group of your standard infectious microbes, which in turn means that it got better at fighting them off once it was exposed to them.

The conclusion? Only what common sense tells us: Exposure is good for your immune system-- to a point. Just like a muscle, the immune system can only stretch so far before straining. The practical implication is that we shouldn’t go overboard on the antibiotics for things that our immune system can easily handle.