Sorting by

×

How flossing your teeth could lower your risk of stroke

Research has shed new light on the wide-ranging health benefits of flossing, even among people who already brush their teeth regularly

This is Everyday Science with Clare Wilson, a subscriber-only newsletter from The i Paper. If you’d like to get this direct to your inbox, every single week, you can sign up here.

Hello, and welcome back to Everyday Science.

I recently had a stroke of great good fortune. After years on a waiting list, I have secured a place as an NHS patient at my local dentist.

In preparation for my long-overdue check-up, I have been extra diligent with the tooth floss, so I was pleased to see research released this week suggests people who regularly floss their teeth have a lower risk of stroke.

This comes after a large body of previous research has found links between dental health and broader physical health.

And yet, there are still question marks over whether these findings reflect causal links or just statistical correlations. So how strong is the evidence for the wider benefits of good dental health, and what could be the explanation?

Plaque build-up

When people don’t brush their teeth well enough, there is a build-up of plaque – a sticky film on the teeth composed of bacteria and compounds from food.

Over time, calcium from saliva is deposited into this layer, hardening it into unsightly tartar, which can only be removed by the dreaded scraping tool of the dental hygienist – a process I have recently become very familiar with.

But plaque and tartar also have more serious consequences, in that the permanent presence of bacteria on teeth can progress to inflammation of the gums known as gum disease, or gingivitis.

“The higher build-up you’ve got of this plaque, the more you have bad bacteria, growing in conditions that would favour a virulent state,” said Professor Karolin Hijazi, a consultant in oral medicine at the University of Aberdeen.

Gingivitis is bad enough, as gums become red and sore, and are prone to bleeding. But over the past three decades, multiple studies have linked various hallmarks of gum disease with a higher incidence of conditions ranging from strokes and heart attacks to cancer and Alzheimer’s disease.

The latest research adds to this work, finding that the specific practice of flossing appears to reduce our risk of stroke.

Using an existing study of connections between lifestyle habits and cardiovascular health in more than 6,000 Americans, researchers found that flossing at least once weekly or more was linked with a 25 per cent lower risk of ischaemic stroke (the most common kind) over 20 years. The work is due to be presented at the American Stroke Association’s International Stroke Conference in Los Angeles next week.

The findings fit with our existing ideas, because it makes sense that flossing would improve gum health. But it was surprising that an apparent benefit from flossing was present, even in people who reported frequently brushing their teeth, said Professor Souvik Sen, a neurologist at the University of South Carolina, who led the study.

Inflammation cascade

What could be the mechanism for the effects of gum disease on the rest of the body? There are two main theories. The first is that inflammation of the gums leads to a body-wide form of inflammation, where there is permanent low-level activity of the immune system.

Such “systemic” inflammation could cause strokes by disturbing the rhythm-setting cells of the heart, which would cause irregular heart beats, a known risk factor for stroke. And it can contribute to narrowing of arteries, which can lead to heart attacks.

The second theory is that the breaks in gum tissue let bacteria get into the blood, letting them colonise other sites in the body, such as heart valves or even the brain. Or both inflammation and bacterial escape could be happening, said Dr Angela Nobbs, a microbiologist at the University of Bristol.

Cause or correlation

The caveat with most of the work in this field, though, is that it doesn’t prove that poor dental health causes the medical conditions – only that it correlates with them. “The big question is whether it’s causal versus correlative,” said Dr Nobbs.

It could be that something else is causing both gum disease and the medical condition – for instance, smokers are more likely to have both bad teeth and heart attacks.

What we really need are large randomised trials to see if an intervention like giving people free dental treatment protects them from heart disease.

So far only one such pilot study has been done and it included too few people to give us any reliable conclusions.

Some light has been shed, however, by randomised trials that found dental treatment does reduce markers of inflammation in the blood, such as a biochemical called C-reactive protein, or CRP.

Much previous work has linked higher levels of CRP with higher rates of multiple medical conditions – including heart attacks, cancer and Alzheimer’s disease.

Another piece of evidence comes from the latest study on flossing and strokes, which found people who flossed more often had the biggest cut in stroke risk – which supports the relationship being causal, said Professor Sen.

“If somebody flossed once a week, that was enough to reduce it, but as they increased the frequency to twice or three times, it had a ‘dose-response’ effect. That was very intriguing, because whenever there’s a dose response curve, it usually indicates that the intervention itself has an effect.”

Nevertheless, the theory still isn’t proven, said Dr Nobbs. “We still need [large] randomised clinical trials that will, once and for all, be able to identify gum disease as a risk factor for these conditions that can be modified – so if you treat gum disease, you reduce the risk,” she said.

Yet even without such evidence, it is still worth doing your very best with your dental hygiene, said Dr Nobbs. After all, if the theory turns out to be wrong, what’s the worst that could happen?

You don’t change your risk of heart disease, but you do end up with very clean teeth.

I’ve also written

Imagine you start developing symptoms of dementia – memory lapses and losing your train of thought in conversations. You might make major changes to your life, even quit your job.

But some people in this position eventually that they have a completely different condition, which only mimics dementia’s symptoms. And the good news is that it has a much better prognosis – and can even be completely cured.

I’ve been reading

I have been enjoying The Last Devil to Die, Richard Osman’s latest installment in his “Thursday Murder Club” series, about a group of elderly amateur detectives who encounter a Midsomer Murders level of homicides in their locale.

I was sceptical that Osman would be able to produce another book in this series without it feeling repetitive and predictable. But the author has pulled it off with his usual panache and style.

This is Everyday Science with Clare Wilson, a subscriber-only newsletter from The i Paper. If you’d like to get this direct to your inbox, every single week, you can sign up here.



Source link

Related Articles

Back to top button