It’s the time of year when we feel the urge to clear out cupboards, hoover our homes from top to bottom and sanitise every nook and cranny. The habit of spring cleaning has been traced through societies for centuries and, according to research , plays into our human desire for a “fresh start” – we’re driven to clean in the spring in the same way we rush to the gym in January.
However, before you don your rubber gloves and grab an antibacterial spray, it’s worth pausing to consider how your cleaning ritual could be harming your gut microbiome – the trillions of bacteria , fungi and viruses that live in our digestive system and keep our bodies functioning properly. A lower diversity, or having fewer strains of microbes in the gut, has been linked to inflammation, type 2 diabetes, heart disease and a weaker immune system , 70 per cent of which is located in our gut.
“Historically, we’ve seen bacteria in our home as something very bad,” notes Dr Emily Leeming, a microbiome scientist at King’s College London, dietitian, and author of Genius Gut and the upcoming book Fibre Power . “Absolutely, there are dangerous and harmful bacteria but there’s also plenty of bacteria that are harmless – and potentially good for us.”
Here’s exactly why overzealous cleaning could be harming your gut – and what you can do about it.
Why a clean home might be wrecking your gut
Cleaning products like bleach and disinfectant spray kill almost all bacteria, viruses and fungi they come into contact with by damaging, dissolving or inactivating key parts of these microbes, explains Dr Primrose Freestone, a microbiologist at the University of Leicester. In the case of bleach, which is a diluted form of chlorine, this occurs because of its active ingredient sodium hypochlorite, which serves as a disinfectant by attacking and neutralising contaminants. With cleaning sprays, the active ingredients they contain – commonly hydrogen peroxide, benzalkonium chloride or alcohol – have the same effect.
This is how they can eliminate bacteria that cause food poisoning, such as E. coli, Listeria, and Salmonella; the bacteria Staphylococcus, which causes skin infections; fungi such as Aspergillus, which causes lung infections; as well as respiratory and diarrhoeal viruses such as Covid, influenza and norovirus, she explains.
“This is great because even small quantities of these microbes can make you ill,” says Dr Leeming.
However, these products don’t discriminate and also kill “good” microbes. Early research suggests this may be to the detriment of our health, in part due to what’s known as the hygiene hypothesis. This theory suggests that we need to be exposed to germs and viruses to help develop our immune systems.
“This hasn’t been strictly proven,” Dr Leeming notes. “But the idea is that we’re not getting the chance to interact enough with microbes in our environment. We have a lower diversity of microbes in our guts than our ancestors. One of the reasons for this could be that everything around us is far too clean and we’re over-enthusiastic with cleaning products,” she says.
Some research backs up the hygiene hypothesis theory. One paper found that children who grew up in households that used multi-surface cleaners every week had differences in their gut microbiome and were more likely to be overweight compared to children who weren’t exposed to these products as frequently.
In particular, they had higher levels of Lachnospiraceae, a bacterium that is especially effective at breaking down food, meaning our bodies can extract more calories from them – potentially explaining why they were more susceptible to weight gain.
As well as a too-clean environment potentially restricting our microbiome, cleaning products themselves may also be contributing to the chemical load that we’re exposed to every day, which is also thought to be worsening the condition of our gut.
“There is the idea that our overall chemical exposure from multiple products – so cleaning products but also perfumes and lotions – has a cumulative effect on our microbiome,” she notes.
So should you banish the bleach and embrace a dirtier home? No, says Dr Leeming. “We don’t want the bad types that are going to cause you harm to persist because you’ll have a worse effect on your gut if you get sick – that’s going to be disruptive to the microbiome itself.”
Dr Freestone also emphasises that the evidence is limited. “No cleaning product, antimicrobial surface spray or disinfectant is harmful to the gut or other body tissues if used as recommended by the manufacturers,” she notes. Yes, our cleaning products kill good bacteria, but, says Dr Freestone, “this is inevitable and a payoff for staying infection free”.
Should you buy ‘non-toxic’ cleaning products?
Some pricey cleaning products contain wording on their packaging, implying that they are better for our health: “Made without parabens” and “free from sulphates, artificial preservatives and colour” are examples.
However, these are not likely to make a meaningful difference to our gut health , according to Dr Leeming. “Though they do contribute towards a lower overall chemical exposure,” she notes.
“The potential impact is more likely to be through skin contact and inhalation, and perhaps there is an indirect effect then on the gut microbiome, but we don’t know fully for sure,” she explains. “Any product that works to kill germs isn’t selective, it kills both ‘good’ and the harmful ones.
“‘Free-from’ claims don’t automatically mean a product is healthier. They tell you what’s not included in the product, but not what’s been used instead or whether it’s actually safer overall. There’s little evidence that avoiding these ingredients improves gut health.”
How to make your home gut-friendly
So if you shouldn’t throw away your cleaning products but still want to make changes for your health, what can you do?
“The biggest thing to consider is how can you safely be in contact with more microbes, to potentially introduce more to your gut,” Dr Leeming says. These are some tips that may help.
1. Only use cleaning products in the kitchen and bathroom
“We want to be using cleaning products in the kitchen and bathroom, which are high-risk areas for microbes that could potentially give us harmful illnesses,” Dr Leeming notes. “I use high-power stuff in those parts of my home. Food poisoning and diarrhoea is going to disrupt your gut more than cleaning products.”
But you could consider cleaning less thoroughly in other areas of the home, such as the living room, where there will be fewer risky microbes, she notes. Here, you could simply clean with a damp cloth, Dr Leeming suggests.
“That might have a small benefit over time – according to the hygiene hypothesis,” Dr Leeming says. “We don’t know for sure what that translates to in terms of health.”
2. Buy some houseplants
While the evidence for switching up your cleaning routine is limited, spending more time around nature has been repeatedly shown to improve gut health. “Bringing nature into your home and getting in the garden is linked to health benefits, a more diverse microbiome and better mental health,” Dr Leeming notes.
This is largely thanks to soil, which is the most biodiverse habitat on earth. One teaspoon contains more than eight billion microbes.
Regular gardening, or tending to a plant indoors if you don’t have a garden, will expose you to more microbes, which research suggests make their way to our gut, she notes.
For instance, one study found that gardeners have more diverse microbiomes than non-gardeners. “Spending time in nature, whether that’s gardening or tending to a potted plant, is helpful for your gut,” she says.
3. Get a pet
“We see that people who have pets seem to have higher levels of some microbes that are similar to their animals,” Dr Leeming says.
Research shows that children who grow up with a dog or cat in their home have a richer gut microbiome and higher levels of Oscillospira and Ruminococcus bacteria, which are linked with a lower risk of obesity.
Dog owners over the age of 65 can also benefit, with a study finding that they had a more diverse gut microbiome, too. It’s that diversity – a large range of different types of microbes – that has been repeatedly linked to better overall health.
“It makes sense, in a way, that we are sharing microbes back and forth with our animals as much as we are with who we live with in our homes,” Dr Leeming adds.
4. Invite friends over for meals
“We pass microbes back and forth constantly, whether that’s while giving someone a hug, sharing a meal or shaking hands,” Dr Leeming notes.
This bacterial exchange occurs through droplets of saliva that we release when chatting with someone, or coughing or sneezing near them, as well as touching shared surfaces.
This happens to such an extent that people who live together have closely matched gut microbiomes, research shows. Inviting people over will bring more bugs into your home and facilitate the swapping of microbes, she adds.
