Tim Spector: “Dog owners have more diverse gut bacteria” – here’s why

Do dogs make you healthier? World-leading gut health expert Tim Spector explains how they support our gut health, and what you can do if you don’t own one.

They never judge you, they keep you company on walks and they’re always ready with a warm, tail-wagging greeting. Minus having to clean up their poo, there are plenty of reasons we love our four-legged friends. And now there could be another one.  

Tim Spector, world-leading expert on gut health and professor of genetic epidemiology at King’s College London, has revealed that having a dog is good for your health and gut microbiome.  

“Dog owners have more diverse gut microbes than people without dogs,” he says. A 2020 study, published in the journal Frontiers in Cellular and Infection Microbiology, confirms this. It examined the gut microbial composition and diversity of those who have animals, with dogs and cats being participants’ most commonly owned pets. 

Woman cuddling a dog, who is sticking its tongue out.Credit: Shutterstock/Ground Picture

Spector adds that dogs have a significantly greater positive effect on gut bacteria compared with other pets. However, he points out that it’s difficult to measure the size and significance of this effect. 

But since a more varied microbiome is considered a healthier one, this means our furry companions could be playing a part in supporting our gut health. 


Older male owners might reap more rewards

More specifically, research into dogs and health as we age has shown that dog owners’ gut bacteria diversity is improved particularly in older men. A 2022 study, published in the PLOS ONE journal, looked at data, including stool samples, from 54 dog owners and 54 people who didn’t own dogs, all aged over 65.  

“Dogs share their bacteria with us.”

Results showed that dog ownership can regulate the composition of gut microbiota as well as promote the growth of beneficial microbes and suppress the number of harmful bacteria.

The study further compared the gut bacteria of the men in the study with and without a dog as well as the women with and without a dog. It found that a higher number of beneficial bacteria were present in the men who owned dogs. 

What is the gut microbiome?  

The gut microbiome is the trillions of microorganisms (bacteria, viruses and fungi) that live in our digestive tract. Scientists are still learning about our microbiome, but it’s estimated that each person has around 1,000 species of bacteria in their gut 

What about other pet owners?

Have a feline or smaller fluffy family member? Don’t worry. Spector says other animals, such as cats, can still provide benefits.

A 2021 study, published in the journal Animals, shows that higher levels of several species of friendly bacteria were found in those who own pets compared with those who don’t 

What to do if you don't have a dog:

Don’t have a canine companion? You can still boost your gut health. While Spector says, “This is not going to provide the same benefit for your gut as living with a dog and having close contact with that dog and its microbes,” regular exposure to a dog could still support your gut bacteria diversity.

Here are some ideas for spending time with a dog when you don’t own one: 

  • Use BorrowMyDoggy: This service allows you to connect with local dog owners to take care of their dog when they are unavailable, whether that’s at weekends or when they are away on holiday, for example. You can even simply “borrow” someone’s dog to take for a walk.
  • Turn to your neighbours: Know a dog owner in your neighbourhood who can’t get out and about easily or is out of the house a lot? You could offer to spend time with or walk your neighbour’s dog for them. Maybe you could even become a regular dog walker for several of your neighbours’ dogs (to be on the safe side, you might want to ask the dog owner to check with their pet insurer if you plan to walk their dog regularly).
  • Offer to dog sit: If you have a friend or family member who has a dog and is going to be out of the house for a long period or is going away, you could take the opportunity to dog sit or house sit. That way, they don’t need to worry about their dog, and you get to spend time with them.
  • Help out at a dog rescue charity: if you have some spare time and a love for dogs, you could volunteer for your local dog rescue shelter. You can also visit the Dogs Trust website to find volunteer opportunities near your area. 

How do dogs support our gut health?

Spector says: “Just like any other household member, dogs share their bacteria, gained from their paws and sniffing various surfaces, with us.” These species transfer through close contact. It might sound a little disgusting, but this can be beneficial for our health. 

Just how long do you need to have owned your dog or other pet to obtain these benefits? Spector says how length of ownership influences diversity of gut bacteria currently isn’t known. So more research is needed.   

However, if bacteria can be shared between pets and humans so easily, you might be wondering if there are any downsides. As with many things in life, there are risks as well as benefits.

For example, antibiotics are given to animals more than to humans, which means the microbes in a pet’s gut can become resistant to them. If these microbes were to transfer to the owner, this could in turn increase our resistance to antibiotics. 

How pets indirectly support your gut health

The fascinating gut-health benefits that your four-legged friend can provide extends beyond the variety of your bacteria. Spector says: “Stroking and cuddling pets has been shown to lower levels of the stress hormone cortisol. Reducing this is really helpful in supporting mental health.”  

The companionship of a pet can also help to combat loneliness. Pet owners are 36% less likely than non-pet owners to report being lonely. As well as stress, loneliness and mental health are connected, and social isolation can lead to poorer mental wellbeing.


Mental health is closely linked to our gut health, thanks to the gut-brain axis – a two-way communication system between your gut and brain. Reducing stress can even help to manage certain gut conditions such as IBS. Read our article on stress and IBS to learn more. 

What’s more, evidence shows that having a dog can increase older owners’ willingness to exercise, because they need to walk the dog daily. Walking the dog regularly can increase physical activity in older adults.

And exercise affects gut health in many positive ways, from preventing constipation to promoting regular bowel movements and gut microbe diversity. 

While having a dog is good for your health, there are other ways to look after yourself. Check out non pet-related ways to improve your gut health.

Gemma Harris

Written by Gemma Harris she/her


Gemma Harris has been a journalist for over seven years and is a self-confessed health and wellbeing enthusiast, which led her to specialise in health journalism. During her career, she has worked with top editors in the industry and taken on multiple high-discipline fitness challenges for certain outlets. She is particularly passionate about nutrition; after being diagnosed with irritable bowel syndrome in 2016, she discovered her fascination for gut health and founded thegutchoice.com – a dedicated space for providing a hopeful outcome for people with gut issues. Gemma’s core aim is to help others through her writing.

Previously a freelance journalist, Gemma has written about topics including combatting the spread of health misinformation on social media, how to follow a vegan or vegetarian diet with a stoma and probiotics for gut health. Her work has been published within leading health journals such as Gastrointestinal Nursing and the British Journal of Healthcare Management, as well as multimedia health and lifestyle platforms, including calmmoment.com, StomaTips, Fit&Well, LiveScience and metro.co.uk.

She is the proud owner of two adorable guinea pigs who are far too spoilt and have become her writing companions. When she is not writing, Gemma can be found making a colourful and nutritious meal in the kitchen, walking in nature, at a yoga or spin class, swimming, doing an at-home YouTube workout, snuggling up with a self-help book or meditating. These experiences help to influence and shape the content she creates. And because life is all about balance, Gemma also enjoys having cocktails with friends.

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