Can you be too clean?

We take long showers, change clothes every day and wash our hands regularly. Is

this doing us more harm than good?

What s your routine? Do you shower every morning, or skip a few days? Do you

change the bedsheets weekly, or only when they get smelly? How about your

towels: New ones like clockwork every Saturday, or do you wait until they

are, well, just that a touch on the manky side?

We live in an age of cleanliness. Our soaps are antibacterial. Our household

cleaners promise to kill 99.9% of germs. Microbes are bad, plain and simple.

But at the same time, some scientists also tell us that being too clean is also

wrong, because it might help cause asthma and allergies. So is there a balance

between keeping obsessively clean and learning to live with the bacteria all

around us?

Not all of our body has to be washed as stringently as our hands (Credit: Getty

Images)

We have known since the late 19th Century and the discoveries of German

physician Robert Koch that certain bacteria cause specific diseases. Since

then, sanitation and cleanliness have dramatically improved our health.

Yet not all microbes are bad. Yes, there are bacteria that cause unpleasant or

even deadly diseases, but lots of them are extremely useful and beneficial to

our health. They make vitamins in our gut, coat our skin to protect us from

harmful microbes, and help us digest food. Outside of our bodies, they

decompose organic waste, make half the world's oxygen and fix nitrogen levels

in the air helping make the Earth the life-supporting planet it is. Today,

many scientists argue that people have become too clean for their own good.

We need contact with the microbial biodiversity from the environment Graham

Rook, University College London

In 1989, the British epidemiologist David Strachan was the first to suggest

that the exposure to infections during childhood would provide a good defence

against allergies in later life. It s an idea known as Hygiene Hypothesis .

An allergy is, in fact, our immune system going haywire, by perceiving a

harmless substance as a major attack. Our bodies, says Dorothy Matthews,

biologist at Russell Sage College in Troy, New York, may overreact to

beneficial microbes, because our immune systems have forgotten how to live with

them.

For this reason, we may have to understand how microbiota the microorganisms

living on and in our body can help us. It is essential to pass on the

maternal microbiota symbiotic harmless organisms in the gut, skin and

elsewhere and we need contact with the microbial biodiversity from the

environment, says Graham Rook, an epidemiologist at University College London.

Weeding out pathogens

Take a baby s dummy that s fallen to the floor. It s better for the mother to

suck it clean rather than provide a new sterile one, he says, because this has

been shown to accelerate development of the infant's microbiota, and reduces

allergies. One could arguably describe it as exposure therapy, starting with

food. Eat a varied diet, preferably with farm produce, says Rook. It s also

better to exercise in nature, not a gym. And while we might think dogs are

dirty, they also help most of us to increase microbial biodiversity and reduce

allergies.

In a way, the immune system is like a farmer. It makes sure that our bodies

have the microbes that are important for our development, physiology,

metabolism, even brain functions, while at the same time doing plenty of

weeding, getting rid of the microbes that contain pathogens. No wonder that a

lack of diversity in our microbiota is associated with a huge range of

illnesses. Having said that, there is still no convincing proof that the lack

of a specific type of microbe can cause a particular disease. This might well

come one day, says Rook, but the problem is technically and statistically

enormously complex.

Some scientists believe our lack of contact with bacteria may be behind a rise

in allergies and asthma (Credit: Getty Images)

Others agree. The microbiome has been linked to immunity, autism, allergy,

autoimmunity, mood, and the development of our central nervous system, says

Mary Ruebush, microbiologist and instructor at Becker Professional Education

School. And this exposure therapy begins the moment we are born children who

are delivered vaginally have much lower rates of allergy than those delivered

via caesarean, possibly because of this early exposure to the mother s normal

vaginal flora, she adds.

Our exposure to good microbes early in life can be an enormous benefit to our

health, explains Rook. For instance, early exposure to microbes in our gut

activates some immune cells in such a way that as we get older, they do not

over-respond to microorganisms. Rook calls these microbes our old friends .

And we are missing their friendship, because extreme cleanliness means that

often we don t come in contact with microbes in the same way that our ancestors

did.

Overall obsessive washing disrupts the normal flora which keep you healthy by

competing with harmful organisms

This presents something of a conundrum for people hoping to live healthier

lives. How can we avoid disease from the bad bacteria, while still fostering

the good bacteria? Rook certainly wouldn t advocate skipping the essentials,

such as washing your hands. Scientists consider dirty hands as one of the most

likely reasons why infections are passed between us. Getting your hands clean

is not just a question of how long you wash them, but how well . You have to

apply soap and water, rub all surfaces of the hands thoroughly for at least 15

seconds, then rinse under running water and then dry them, say the experts. The

rubbing with soap detaches the germs from your skin, while the rinsing takes

them off the hands.

But not all of our body has to be washed so stringently. Overall obsessive

washing disrupts the normal flora which keep you healthy by competing with

harmful organisms , says Ruebush. Operating your immune system in an

environment of sterility is like a sensory deprivation for the brain.

Eventually, it goes insane, thus the increased amount of allergy and

autoimmunity associated with persons who try too hard to avoid all exposure to

anything in their environment, she says. A long shower every day may not be

advisable, as it removes the good bacteria from our skin. But you should wash

around your genitals and anywhere you sweat a lot. And you should change your

underwear every day.

Some of the helpful bacteria on our skin helps protect us from more harmful

bugs (Credit: Science Photo Library)

Around the house, the solution for fighting the wrong kind of bacteria is not

excessive cleaning, but timely cleaning. Good hygiene is not a once-a-week,

deep-down clean, it needs to be an ongoing part of our daily lives, where

hygiene measures are targeted where and when necessary," says Sally Bloomfield,

of the London School of Hygiene and Tropical Medicine, and chair of the

International Scientific Forum on Home Hygiene.

Take chopping boards in the kitchen. If you cut your greens, it s ok to wait

until after dinner to do the washing up. Not so if you ve chopped raw fish or

meat. Instant action is required, or you could put your family at risk of

infection.

After all, it s well established that about 70% of all chicken are contaminated

with Campylobacter, a bacterium which can cause food poisoning and will happily

multiply on your chopping board.

Damp dangers

Hospital studies show bedlinen and towels can easily spread viruses and germs,

but our homes are not quite the high-risk environment that will breed the next

superbug. But fluffy wet towels can be a problem.

There is no scientific data which could allow us to explicitly state how often

we should change bed linen, towels etc, says Bloomfield, but there is enough

data to say that they can be an infection risk in the home. She recommends to

change bedlinen and towels about once a week, and warns strongly against

sharing hand towels and other personal care items.

If you chop meat on a chopping board you should wash it right away (Credit:

Science Photo Library)

Warm damp cloths are a particular haven for nasty bugs, says Bloomfield. That s

why cloths in both the kitchen and bathroom should ideally be discarded and

washed after every use. Failing that, at least rinse them well immediately

after use and dry them, recommends Bloomfield. Tea towels, meanwhile, are

ideal for drying dishes, if you are keen to spread your germs to all the

glasses and plates in your cupboard. Regular, even daily swaps are highly

recommended. And laundry of towels and linen should be done at 60C (140F) to

beat the bugs, or with oxygen-based bleaching agents in the washing powder if

it s done at lower temperatures.

When it comes to bathrooms, it doesn t help, of course, that all-too-few people

close the toilet lid when flushing. If you can t be bothered, remember that an

open lid is a gateway for all the bacteria inside to spread and multiply.

Let your children play in places where they have contact with soil and

vegetation, which are rich in beneficial microbes Ilkka Hanski

Pyjamas are another weak point in many people s personal hygiene. Some surveys

suggest that many make the smell test before putting them in the wash. Change

them at least once a week, say the experts. Ultimately, it s all about getting

on top of the critical [infection] control points, says Bloomfield.

The overall message, then, is not that we should return to living in squalor as

to try to embrace good bacteria; we need to be just as vigilant without our

homes to keep them free from germs. Instead, Ilkka Hanski, a biologist at the

University of Helsinki in Finland, says, it s important to get out of the house

and spend time in woodlands and forests. Let your children play in places

where they have contact with soil and vegetation, which are rich in beneficial

microbes, he says. If you have a house, don t maintain a lawn, let native

plants take over and grow taller. Cut them once or twice a year.

Strength after sickness

Studies show the benefits. Children who grew up in an environment that was not

obsessively clean have lower rates of allergy and asthma. And certain bacteria

also actively protect us from bowel disease and even some types of anxiety and

depression.

A healthier life, it seems, can be boosted by exposure to farm animals and

harmless but vital microorganisms in dirt, food, and water. Microbial exposure

is important for promoting the development of effective regulatory pathways

that keep inflammation under control, says Thom McDade, a biological

anthropologist Northwestern University in Evanston, Illinois.

If the hygiene hypothesis is correct, it may explain the rapid rise of both

asthma and allergy cases during the past 20 years. Of course, there are other

explanations too, for example public health trends such as the widespread use

of purified water, the overuse of antibiotics, and of course changes in our

environment such as higher levels of pollution.

Living with a dog could help give your immune system a boost (Credit: Getty

Images)

It is likely that many factors that are part of the Western lifestyle are

involved. Antibiotics will disturb the beneficial microbes in our bodies and

thereby harm the immune responses, says Hanski. In contrast, he adds, studies

clearly show that vaccines are not harmful and play no role in the increase in

allergies.

On the plus side, says Ruebush, you can take heart in knowing that every time

you get a little sick, you get a little stronger. The message is not one that

most people want to hear: they want the quick pharmaceutical fix for the

slightest bit of discomfort. But every time you take the quick fix, you make

your body a little weaker. That s something to remember the next time you re

tempted to slather on the shower gel.