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Dr Sam Jethwa, founder of Bespoke Smile, reveals surprising link between oral health and 'chronic diseases'


Good dental hygiene goes further than just a smile


Split image showing Dr Sam Jethwa and patient in dentist chair© Getty
Francesca Shillcock
Francesca ShillcockDigital Travel Editor
August 8, 2025
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Gut health is a big movement in the health and fitness space right now.

From viral TikTok videos offering inspiration for gut-friendly recipes to cookbooks being published solely focusing on gut health, it's become a hot topic.

As someone with a keen interest in health, fitness and nutrition, it's something I often find myself reading about more and more. 

But what I was surprised to learn is that gut health and oral health go hand-in-hand. It turns out, when it comes to "good" bacteria and "bad" bacteria, they have a lot in common.

Dr Sam Jethwa, leading dentist, President of the British Academy of Cosmetic Dentistry, and founder of the award-winning Bespoke Smile, spoke to HELLO! to give his take on why good oral health goes beyond a pearly smile, and how gut health and oral health can work together to the other thrive.

How oral health and gut health are linked

Dr Sam notes that after the gut microbiome, the oral microbiome is the "second most diverse community of microorganisms living within the human body", and it's unique to each individual.  

"There are around 700 different species of bacteria living within the oral microbiome (including bacteria, fungi, viruses and protozoa), which mainly reside on the teeth and the soft surfaces of the mouth, including the cheeks, tongue, gums and tonsils."

Keeping our bacteria in our mouths is important for preventing major issues such as cavities, tooth decay, gum disease, plus cosmetic concerns such as fresh breath, but it goes much further than that.

stock image close up of white teeth
Oral hygiene is linked to gut health according to Dr Jethwa

"The oral microbiome is not isolated. It's connected to the rest of our body. Bad bacteria in the mouth can travel and have an impact on our gut health and immunity," says Dr Sam.

"There is emerging evidence to suggest that oral health and gut health are closely connected. Bacteria in the gut microbiome can impact the oral microbiome, and vice versa!"

So, it's time we considered what we eat and how it has a direct impact on our oral health.

Tranquil Bliss: Anonymous Woman Lying on Yoga Mat, Hands on Belly in Relaxation© Getty Images
Gut health is a hot topic in the health and fitness space

This is because, as Sam explains, bad bacteria in the mouth will travel to our gut and infiltrate the good bacteria existing in the gut, leading to problems such as bloating and inflammation.

"Also, bad breath can be a sign of an unhealthy gut, which may be due to gastric reflux or an increase in bad gut bacteria.

"This type of halitosis can often have a sulphur-like smell.  Bad breath can also be linked to diets that are high in protein or high in acid, as this can disrupt the PH balance in the mouth."

teeth whitening red lipstick© Bob Thomas
Good oral hygiene helps out gut stay in tip top condition, and vice versa

How a gut-friendly diet promotes good oral health

It's clear it works both ways. A diet that promotes 'bad' gut hygiene can affect your oral health, and poor oral hygiene can affect your gut health.

The question is, how do we make sure both are in tip-top condition?

Dr Sam says: "Good bacteria in the gut can help to promote good bacteria in the mouth, potentially helping to fight gum disease and keep your teeth healthy. 

Dr Sam says a high fibre diet will help gut health and, in turn, oral health© Getty Images
Dr Sam says a high fibre diet will help gut health and, in turn, oral health

"A nutrient-dense diet that is rich in high fibre foods and probiotics can help to promote a balanced oral microbiome."

He adds: "Brushing with a fluoride toothpaste twice a day is key (opt for an electric if your technique needs improving with a manual), along with flossing each day and regular dental check-ups.

"A low sugar diet is also important for oral health, as bacteria thrive off sugar in the mouth, which leads to the formation of plaque."

Close-up of a female patient being checked by an unrecognizable woman dentist© Getty Images
Dr Sam says we need to think of oral health and overall health

Other diseases linked to bad oral health  

It's not just poor gut health that can be caused by bad oral health. There is now increasing research that links longevity and chronic diseases with oral health.

Dr Sam adds: "People need to start thinking of oral health as overall health; maintaining a good dental routine goes further than just a healthy smile."

The British Heart Foundation previously revealed that sixty-nine per cent of those with gum disease have a higher chance of developing Type 2 diabetes, which in turn increases the risk of heart disease and other cardiovascular issues. 

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