Every bug – good or bad – is wiped away by battalions of cleaning products to achieve a ‘healthier’ living environment. The paradox is, we need most of these little fellas to keep us healthy.

The Western world may have cleaned itself into a corner in an effort to protect itself from harm. Bugs and good health aren’t usually uttered in the same breath, but we’ve got to get our heads around a new way of thinking. Whether we like it or not, we are walking bug hotels: adults cart around about 300 trillion bugs every day, adding about 1.3kg to their weight. These bugs are our microbiome. When we wage war on them, we wage war on own immune system.

The hygiene hypothesis

This ideology forms the basis of the hygiene hypothesis, which was first proposed in 1989, and advocates that exposure to infections early in life is needed to prime the immune system and suppress the development of allergic and autoimmune conditions. It suggests that a young child’s environment can be too clean, with lack of exposure to germs leading to defects in the establishment of immune tolerance. Critics of this theory argue that it’s been used to suggest modern hygiene standards are bad for our health.

There’s no doubt the deadly infectious diseases that once wreaked havoc on entire populations are best left in history books. But denying our immune system the chance to flex its muscle and toughen up by facing up to some dirt isn’t good, either. There is a balance. And an alternative theory. The International Scientific Forum on Home Hygiene (IFH) has reported that losing touch with microbial ‘old friends’ may be a fundamental factor behind the rises in an even wider array of serious diseases, including chronic inflammatory diseases (CIDs) such as type 1 diabetes and multiple sclerosis.

“The underlying idea that microbial exposure is crucial to regulating the immune system is right. But the idea that children, who have fewer infections because of more hygienic homes, are then more likely to develop asthma and other allergies does not hold up,” says Honorary Professor at London School of Hygiene and Tropical Medicine, Sally Bloomfield. Professor Graham Rook, who first proposed the Old Friends hypothesis in 2003, partly attributes the rise in allergies and inflammatory diseases to gradually losing contact with the range of microbes our immune systems evolved with way back in the Stone Age. “Only now are we seeing the consequences of this, doubtless also driven by genetic predisposition and a range of factors in our modern lifestyle – from different diets and pollution to stress and inactivity. It seems that some people now have inadequately regulated immune systems that are less able to cope with these factors.”

We’ve also lost touch with our ‘old friends’ in other ways. Our modern homes have a different and less diverse mix of microbes than rural homes of the past, mostly because microbes come in from outside, and the microbes in towns and cities are very different from those on farms and in the countryside. “How we can begin to reverse the trend in allergies and CID isn’t yet clear,” says Rook. “There are lots of ideas being explored, but relaxing hygiene won’t reunite us with our Old Friends; just expose us to new enemies like E.coli O104.”

Reconnecting with 'Old Friends'

Bloomfield says, “The good news is that we aren’t faced with stark choices between running the risk of infectious disease or suffering allergies and inflammatory diseases. The threat of infectious disease is now rising because of antibiotic resistance, global mobility and an ageing population, so good hygiene is even more vital to all of us.” She explains science shows us that our microbiome constitutes an organ, as essential to health as our liver and kidneys. To tackle diseases related to immune dysfunction and infectious diseases in future, Bloomfield says we are all - health agencies and the public alike - going to have to view our microbial world very differently. “One important thing we can do is to stop talking about ‘being too clean’ and get people thinking how we can safely reconnect with the right kind of dirt.”

When it comes to reconnecting with our Old Friends, Facebook and text messaging won’t cut it (sorry Gen Z) – we need to reconnect in person! Some strategies could be natural childbirth wherever possible to coat the newborn in mum’s bugs, healthier diets (hint – ditch processed foods), reduced antibiotic prescribing, and spending more time in the great outdoors. “Good hygiene is based on knowing how harmful microbes are transmitted around the home and other environments, and targeting hygiene practices in the places and at the times that matter to prevent these microbes from spreading, most particularly times associated with activities such as food, respiratory, hand and toilet hygiene,” says Bloomfield. Timing of initial exposure may also be critical. Dr Robert Wood, Chief of the Division of Allergy and Immunology at the Johns Hopkins Children’s Center, says many of our immune responses are shaped in the first year of life.

The dirt on cleaning products

Ecostore Co-Founder Melanie Rands says it might seem like the right thing to use an antibacterial hand wash or soap, yet they have been proven to have no better cleaning properties than normal soap. “They are often loaded with nasty chemical ingredients as well such as triclosan that strip your skin of its natural protective oils, and can aggravate the skin, leaving it red and itchy,” she says. “Using too many germ-killing products in pursuit of a sterile home can actually work against a child's healthy immune system. Another possibly harmful ingredient to check for is sodium lauryl sulphate, often found in detergents and stain removers. It’s known to be a skin irritant and can be contaminated with carcinogens. When you’re using home cleaners, consider measures to maintain indoor air quality and reduce your children's exposure to the chemicals in them that could cause harm.”