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The Hygiene Hypothesis: Are You Too Clean for Your Own Good?

Gerald Heneghan

Can you be too clean for your own good? We look at how a little bit of dirt could actually be good for your health.

With all the miraculous cleaning products at our disposal, it’s all too easy to become a bit obsessed with cleanliness – especially when it comes to our children.

But could a lack of exposure to dirt and bacteria in early life weaken your immune system and leave you vulnerable to allergies and sickness? In this guide, we’ll find out.

What is the Hygiene Hypothesis?

Bath tubThe idea that exposure to certain kinds of infections can strengthen our resistance to disease isn’t a new one. After all, it’s the principle behind vaccinations, which first came to light in the 18th century.

But it wasn’t until the 1980s that what’s known as the ‘hygiene hypothesis’ was formally proposed. It’s suggested that when the immune system lacks practice in fighting off infections, it becomes prone to overreacting to non-threatening substances like pollen.

Research and Evidence

In an article for the British Medical Journal, researcher David Strachan investigated whether lower levels of infections during early childhood could be to blame for the massive rise in allergic diseases during the 20th century.

He found that children raised in households with more members were less likely to develop hay fever, suggesting that the exposure to germs from their siblings could provide additional protection against the condition.

These findings prompted further research into the hygiene hypothesis, with studies finding that children in developing areas of the world were less likely to develop allergies and conditions like asthma than those in wealthier nations.

Similarly, a comparison of the rates of allergies and asthma between East and West Germany found that East German children raised in dirtier, more polluted areas were less likely to develop these conditions in later life.

Germs and bacteriaOther researchers built upon these findings, discovering that being exposed to germs provoked an internal inflammatory response among children who were brought up in cleaner environments.

And another study found that people who grew up on dairy farms were much less likely to develop allergies and asthma, suggesting that exposure to low doses of bacteria contained within ‘farm dust’ could provide life-long to children raised in these environments.

While it’s worth noting the above stories only looked at correlation between living conditions and the development of allergic conditions, they’re backed up by some promising evidence.

Epidemiological studies (that look into the rate and distribution of how disease develops) have backed up claims that the incidence of autoimmune diseases are much less common in developing areas of the world.

And experimental evidence also supports the hygiene hypothesis, showing that the risk of such conditions developing increased when short-lived T cells (a key part of the immune system) were replaced during a period where too few long-lived T cells were knocking around (due to a lack of infections).

Alternative Explanations

Since it’s not possible to take someone’s immune system apart and see exactly what makes it tick and it’s not ethical to confine children and subject them to various conditions to see if they develop allergies or asthma, several other explanations have been proposed to dispute the hygiene hypothesis.

For instance, some suggest that exposure to pollutants, whether children were breast-fed and even whether they regularly used chlorinated swimming pools could play a role in the development of autoimmune conditions.

Too Clean For Your Own Good?

Cleaning products.So should you encourage your kids to go and roll around in the muck? Not so fast.

While evidence suggests you should avoid raising children in an overly-sterile environment, it’s still important to protect them from the sorts of conditions that can cause serious sickness.

As such, you should make sure to regularly clean and disinfect surfaces to make sure nasty microbes like E.coli and salmonella aren’t spread (especially in places that have had contact with raw meat or poo).

But you shouldn’t strive to have a completely dirt-free home and don’t be too worried if your kids get a bit dirty while playing outside.

Your Turn

Were you brought up in an overly-clean home and later developed allergies or asthma? Or do you have any questions about this fascinating topic.

Either way, be sure to get in touch via Facebook. We always love to hear from you.

And if you’re looking for expert advice on managing allergies or protecting your children’s health – simply hit the button below to talk to a UK-based GP right now:

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Topics: Health