A stronger body, a better brain, less stress: we all want it, but how do you go about it? There are thousands of scientific studies on things that are good for the body and mind… But how do you ever read them? To help you on your way, every Monday we highlight one activity: 5 scientifically proven reasons to do something more (or less) often. Today: five reasons to be a little dirtier. About hand hygiene, pets and bacteria that help against anxiety and stress. But hey, we riders have known for a long time that working with horses and in the stables is good for your health.
Hygiene is important, we learn that from an early age. “Wash your hands. “Brush your teeth.” “Keep it clean.” There are good reasons to be a bit dirtier, though. Too much washing upsets your skin flora. A cat or a dog bring extra bacteria into the house, but that is good for your immune system. Digging in the earth with your hands is good for your brain.
1. Corona made us too clean
The coronavirus has made us aware of the importance of hygiene. Hand gels, detergents and soaps are ubiquitous. Whoever goes to the supermarket has to disinfect his shopping trolley first. We even scrub surfaces to prevent infection.
We do not do this lightly, of course. During the first months of the pandemic, it turned out that the virus can survive on the skin and on surfaces. Virus particles were found on bank notes, library books, plastic, steel surfaces, surgical masks, clothing, handles, lift buttons, chopsticks in Chinese restaurants, glasses, bottles, ventilation systems… and much more.
“We knew very little about the virus at that time,” says biostatistician Geert Molenberghs (UHasselt/KULeuven). “It is therefore good that this was thoroughly investigated. After all, it could perfectly well have been the way in which the virus spreads. Unfortunately, the emphasis has been placed incorrectly for some time.”
Already last summer it became clear that the coronavirus rarely spreads by touching surfaces or by shaking hands. It is mainly spread by small droplets of saliva in the air and by aerosols.
Only a handful of studies did find evidence of surface contamination. One of these studies mentions the case of a man from China who wiped his nose with his hand and then immediately pressed a lift button. Someone else pressed the same lift button two minutes later and then flossed his teeth with a toothpick. It is one of the rare documented cases of “snot-mouth transmission” of the coronavirus.
“Cleaning shopping trolleys and surfaces has become a bit of a chore,” says Molenberghs. “We put a lot of energy into it. That’s not a bad thing in itself, because it doesn’t hurt to do it. The problem, however, is that we forget the things that are important, such as keeping your distance and wearing a mouth mask.
The old, familiar hand hygiene remains important, of course. Washing your hands after going to the toilet, for example, or before going to the table. But disinfecting your hands dozens of times a day and scrubbing surfaces is superfluous. A bit dirtier is fine.
2. Too much washing disturbs your skin flora
About ten years ago, American scientists went to a village deep in the Amazon forest. They studied the bacteria that live in the stool, mouth and skin of the Yanomami people. The Yanomami are very isolated and their lifestyle has not changed much in centuries.
The research shows that the Yanomami have a much greater diversity of skin bacteria than people in the Western world. This diverse flora protects their skin from skin infections and acne. Those kinds of problems are very rare there.
“This is partly because the Yanomami do not use dermatological products,” says Ingmar Claes (UA/YUN NV), who researches the role of skin bacteria. “Dermatological products disturb the skin flora, especially through the use of preservatives. So-called ‘surfactants’ also have a negative influence. They make a product foam nicely, but they also kill skin bacteria.”
The use of preservatives is not a problem in itself,” says Claes. “Our skin flora usually recovers quickly. It does become a problem if you overdo it. And that is what we do today: we use shower gel and shampoo and lotions and soaps and creams… That overuse can damage the skin flora permanently.
So is it better not to wash (or to wash rarely)?
“Not a good idea,” says Claes. “We have to wash, hygiene is important. Try to choose products that don’t disturb your skin flora, but take into account the importance of your skin bacteria. And avoid products with lots of preservatives and surfactants.”
3. A pet brings extra bacteria into the house and that is a good thing
Do you have a dog or a cat? Then chances are that your house contains more different types of bacteria than the house of people who do not have pets.
“American scientists discovered this by collecting dust in houses,” says professor of microbiology Marie Joossens (UGent). “Then they investigated which bacteria were present in that dust. Pets turned out to have a very big influence. By examining the dust, you can know whether cats or dogs live in a house.”
For another study, samples were taken from families just before they took in a dog. A year later, they measured again. The diversity of bacteria had become much greater with the arrival of a dog.
That sounds dirty, but it is not. This high diversity of bacteria may even be good for your health.
“It seems to have a beneficial effect on the immune system of young children,” says Joossens. “It is important that children are exposed to many different bacteria at a young age. That helps in the development of their immune system.”
Several studies have shown this beneficial effect. Children born into a family with a dog have a more diverse gut flora than children born into a family without a dog, according to research. A large survey study concluded that the presence of a pet during the first years of life reduces the risk of allergies by 18%. Good news for dog lovers: the effect is greater for dogs than for cats.
Whether having a dog (or cat) at home is also good for your immune system in adulthood?
“That has not yet been thoroughly researched,” says Joossens. “From research by the Flemish Intestinal Flora Project, we do know that having a pet also influences your intestinal flora at an adult age. It is not yet clear whether that is good or bad, but based on the research I rather suspect the former.”