The short answer: Nobody has proven it. In a U.S. cohort of 6,200 adults, people who flossed regularly had a 23% lower risk of ischemic stroke over about 24 years. That is an association, not proof of cause. No randomized trial has shown that flossing, or any gum treatment, prevents heart attacks or strokes. Flossing is still worth doing for your gums.

What do studies of flossers actually show?

The most direct evidence comes from the Atherosclerosis Risk in Communities (ARIC) study. A 2026 analysis in the journal Stroke followed 6,200 adults who had their own teeth and no prior stroke. About 65% said they flossed regularly. The median follow-up was 23.7 years.

The researchers counted 434 ischemic strokes. Ischemic stroke occurred in 8.7% of people who did not floss and 6.1% of people who did. After adjustment for other risk factors, flossing was linked to:

  • A 23% lower risk of ischemic stroke (adjusted hazard ratio 0.77).
  • A 40% lower risk of cardioembolic stroke, the type caused by a clot from the heart (0.60).
  • A 12% lower risk of atrial fibrillation, an irregular heart rhythm (0.88).

A Korean cohort of 98,866 adults found a similar pattern. People who brushed at least twice a day and regularly used floss and interdental brushes had a 23% lower risk of ischemic stroke.

Note what these studies measured. The outcomes were stroke and atrial fibrillation. Neither abstract reports a result for heart attack or coronary artery disease.

What about heart attacks specifically?

The evidence here is about oral hygiene in general, not floss. A Korean study of 247,696 healthy adults tracked major cardiovascular events for a median of 9.5 years. These events included cardiac death, heart attack, stroke, and heart failure. There were 14,893 events.

Each additional daily tooth brushing was linked to a 9% lower risk of these events. A professional cleaning at least once a year was linked to a 14% lower risk. People with gum disease, more cavities, or more missing teeth had a higher risk.

That study did not report a result for flossing by itself. So the honest answer for heart attacks is narrower than the headlines. Better oral hygiene tracks with fewer cardiovascular events. Flossing alone has been tied to stroke, not yet to heart attack.

Why doesn't an association prove that flossing protects the heart?

People who floss differ from people who do not. In the ARIC analysis, flossers started with fewer vascular risk factors, less gum disease, and fewer cavities. Statistical adjustment can correct for the factors a study measured. It cannot correct for the ones it missed.

The ARIC data show how this works. Flossers had lower levels of interleukin-6, a marker of inflammation, in the crude analysis. That difference disappeared after adjustment for age, body mass index, and smoking. C-reactive protein, another marker, did not differ between the groups at all.

The American Heart Association looked at this problem in a 2012 scientific statement. It concluded that observational studies support an association between gum disease and vascular disease, independent of known confounders. It also said those studies do not support a causative relationship. Gum disease and artery disease share risk factors, including cigarette smoking, age, and diabetes.

The association published an updated statement in 2026. Its summary describes new evidence, including genetic studies and treatment studies. It still describes the link as an association and lists areas that need more research.

One more caution applies. Flossing in these cohorts was self-reported. One author of the ARIC paper also reported employment by an oral care company.

How could gum disease affect the heart?

Gum disease is an infection that inflames the tissues that hold the teeth in place, according to the National Institute of Dental and Craniofacial Research. Plaque, a sticky film of bacteria, builds up on the teeth and triggers that inflammation.

The 2026 American Heart Association statement describes two possible routes from the mouth to the arteries:

  • A direct route: bacteria from the gums enter the bloodstream.
  • An indirect route: long-term gum inflammation adds to inflammation throughout the body.

Our guide to inflammation and chronic disease covers the wider science of the second route. A plausible mechanism is still not proof that cleaning between your teeth changes your heart risk.

Has any trial tested whether treating gum disease prevents heart disease?

Yes, but the trials are small and the results are inconclusive. A 2022 Cochrane review found only two randomized trials of gum treatment that measured cardiovascular outcomes. It rated both at high risk of bias. One had 165 participants and one death. The other had 303 participants, and the reviewers judged its event data too weak to use.

The reviewers concluded that the evidence was very low certainty and inconclusive. They wrote that further trials are needed to learn whether gum treatment helps prevent cardiovascular disease.

Trials of surrogate markers give a mixed picture. A 2007 randomized trial of 120 patients with severe gum disease compared intensive treatment with standard care. Blood vessel function was worse in the intensive group one day after treatment. It was better at 60 days and at 180 days. No cardiovascular events occurred in either group, so the trial could not test real outcomes.

We found no randomized trial that tested flossing itself against heart attack or stroke.

Does flossing at least help your gums?

Probably, though the proof is weaker than most people assume. A 2019 Cochrane review pooled 35 randomized trials with 3,929 adults. It found that floss or interdental brushes, added to tooth brushing, may reduce gingivitis or plaque more than brushing alone. Interdental brushes may work better than floss.

The reviewers rated that evidence low to very low certainty. Most trials were short. None measured cavities between the teeth, and most did not measure advanced gum disease.

Federal guidance still supports the habit. The National Institute of Dental and Craniofacial Research says early gum disease can often be reversed by daily brushing and flossing. Its tips for healthy gums are:

  • Brush twice a day with a fluoride toothpaste.
  • Floss regularly, or use an interdental brush, a pick, or a water flosser recommended by a dental professional.
  • See a dentist routinely for a check-up and professional cleaning.
  • Quit all forms of tobacco.

The institute names tobacco use as the most significant risk factor for gum disease. The 2012 American Heart Association statement lists cigarette smoking as a risk factor that gum disease and artery disease share.

The bottom line

Floss for your gums. A lower stroke risk is a possible benefit that no trial has confirmed. The advice to floss does not depend on the heart question.

Do not treat floss as heart protection. Keep your attention on established risk factors such as blood pressure, cholesterol, and smoking. Our sister site hypertension.md covers blood pressure in detail. A dental visit belongs on the same list as your annual checkup, and small routines last longer when you build them as habits.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Talk with your dentist and your doctor about your own gum health and cardiovascular risk.