Skipping flossing raises your risk of dying earlier by about 30% compared to daily flossers, according to a long-term study of more than 5,600 older adults tracked over nearly two decades. The habit in question isn’t some exotic wellness ritual or medical intervention. It’s a piece of string most people already own and routinely skip.
The same research, which tracked dental behaviors and survival rates in older adults from 1992 to 2009, found that never brushing at night elevated mortality risk by 20 to 35%, and skipping dental visits increased it by 30 to 50%. What stood out was that flossing and nighttime brushing each predicted survival independently of each other. Brushing in the morning didn’t cancel out the danger of skipping the floss. The two habits work on different parts of the same problem.
That problem begins in a place most people never think of as a source of chronic, life-shortening disease: the space between your teeth. Bacteria that accumulate in those gaps don’t stay put. They seed a cascade of inflammation that researchers are now linking to some of the leading causes of death in people over 40, from heart attack and stroke to dementia and cancer. The mouth is not a separate system. It’s an entrance.
Why Gum Disease Is More Dangerous Than Most People Realize
The CDC notes that daily brushing, flossing, and regular dental cleanings can treat early gum disease, or gingivitis. Periodontitis, the advanced form, is a different matter. It cannot be reversed, only slowed down. Millions of adults are walking around with a condition that is, by definition, doing permanent damage that no amount of future dental care can fully undo.
Twenty-five years ago, researchers at Boston University’s Goldman School of Dental Medicine found that men with periodontal disease were at greater risk of dying earlier. Drs. Raul Garcia and Elizabeth Kaye called it “floss or die.” A follow-up study using an additional 25 years of data and more sophisticated methods confirmed the original finding. Dr. Brenda Heaton, Associate Professor of Health Policy and Health Services Research at Boston University, explained the mechanism plainly: “Periodontal disease delivers a chronic inflammatory burden, and the longer you have that inflammatory burden, the higher the risk of death.”
A 2024 study from Tufts University, published in the Journal of the American Dental Association, found that suboptimal dental visits and infrequent flossing were associated with an increase in all-cause mortality. The research drew on data from both the Women’s Health Study and the National Health and Nutrition Examination Survey, tracking outcomes across thousands of participants over decades.
A 2025 review found that poor oral health is associated with functional impairments, nutritional deficiencies, and systemic health issues including diabetes and cardiovascular disease.
The Bacteria That Travel
Gum disease isn’t just a local inflammation problem. The bacteria responsible for it have been documented far outside the mouth.
Harvard Health Publishing reports that bacteria infecting the gums can travel through the bloodstream, causing inflammation, contributing to tiny blood clots, and increasing the risk of heart attack. Bacteria such as Porphyromonas gingivalis and Streptococcus mutans can enter the bloodstream through cuts in inflamed gum tissue, triggering a systemic inflammatory response and damaging the endothelial cells that line blood vessels, which directly increases cardiovascular risk.
Research confirmed by institutions including Harvard has found oral bacteria inside atherosclerotic plaques, the fatty deposits that narrow arteries and trigger heart attacks. The same bacterium, Porphyromonas gingivalis, has also been found in the brains of Alzheimer’s patients and in the arterial plaques of people with cardiovascular disease.
People with severe gum disease have a three times higher risk of dying from cardiovascular disease compared to people with healthy gums, according to a 2023 meta-analysis published in PLOS ONE that pooled data across multiple research cohorts. That finding has been replicated in peer-reviewed literature over decades.
Gum Disease and Your Brain
The connection between periodontitis and cognitive decline is one of the most active areas of dental research right now.
A 2023 study published in the British Dental Journal found that poor periodontal health was associated with increased odds of cognitive decline and dementia. The association isn’t explained by age alone. Researchers controlled for confounding factors and still found the relationship held.
A 2021 study published in BMC Oral Health found that each additional missing tooth increased the risk of cognitive impairment by 1.4% and the risk of dementia by 1.1%. Those numbers compound. Lose six teeth to gum disease and the cumulative risk becomes meaningful. A meta-analysis published in government medical archives confirmed that tooth loss is associated with increased risk of cognitive decline and dementia, with the greatest impact seen for Alzheimer’s disease and vascular dementia.
The pathway researchers suspect runs through two mechanisms: chronic systemic inflammation driven by oral bacteria, and the physical loss of chewing function, which appears to play a role in stimulating brain activity. Both are worsened by untreated gum disease, and neither is reversible once the damage is done.
For a closer look at how specific oral bacteria may drive Alzheimer’s pathology, this overview of the mouth-brain connection covers the bacterial pathways in more detail.
The Cancer Link Few People Know About
Research has found that people with a history of gum disease were 14% more likely to develop any type of cancer. That figure climbs for specific cancers. Severe periodontitis is associated with a 24% increased risk of cancer overall, with particularly elevated rates for lung and pancreatic cancers.
Research has shown that the gum disease bacterium Fusobacterium nucleatum can travel through the bloodstream to distant tissues, where it causes DNA damage and may accelerate tumor growth – a finding with significant implications because it suggests oral pathogens can promote cancer through a purely bloodborne route, far from the mouth itself.
A 2025 review published in PMC confirmed that the oral microbiome acts as a systemic modifier of cancer development well beyond the head and neck, with Porphyromonas gingivalis, Fusobacterium nucleatum, and Treponema species among the key implicated pathogens.
Researchers at the Harvard T.H. Chan School of Public Health have been at the forefront of this work. Dr. Wendy Garrett, co-director of the Harvard Chan Microbiome in Public Health Center, has described the microbiome’s implications for cancer as spanning prevention to treatment – a research priority that includes the role of oral bacteria in systemic cancer risk. Harvard University ranks as one of the most productive institutions globally in oral microbiome and cancer research by total citations.
Mental Health Is Part of the Picture Too
The downstream effects of chronic gum disease extend into mental health territory. A 2022 study reported by Medical News Today found that anxiety and depression developed in 37% of people with gum disease, a rate significantly higher than in the general population.
The mechanism is likely bidirectional. Chronic inflammation, already elevated in periodontitis, is a known driver of depressive symptoms. People with depression also tend to neglect self-care routines, including oral hygiene, which worsens the gum disease, which in turn amplifies the inflammatory burden. It’s a cycle, and it can be interrupted at the oral hygiene step.
Research from the University of Texas Health Science Center confirms that periodontitis can increase risk for diabetes, cardiovascular disease, and other inflammatory conditions, a body of evidence that has strengthened considerably over the past decade.
The Flossing Numbers Are Hard to Ignore
A 2025 preliminary study presented at the American Stroke Association’s International Stroke Conference found that flossing at least once a week is linked to a lower risk of stroke caused by blood clots blocking brain blood flow, as well as a lower risk of irregular heartbeats.
Compared to non-flossers, people who flossed at least weekly experienced a 22% lower risk of ischemic stroke, a 44% lower risk of cardioembolic stroke, and a 12% lower risk of atrial fibrillation (AFib), which developed in 20% of study participants. The study used 25 years of follow-up data from more than 6,000 participants in the Atherosclerosis Risk in Communities cohort.
The researchers found that the benefits of regular flossing appeared to be independent of tooth brushing and other oral hygiene behaviors, meaning flossing provides a protective effect that brushing alone does not replicate. Study lead author Dr. Souvik Sen, chair of the Department of Neurology at Prisma Health Richland Hospital and the University of South Carolina School of Medicine, explained: “Oral health behaviors are linked to inflammation and artery hardening. Flossing may reduce stroke risk by lowering oral infections and inflammation.”
A 2024 study published in the Journal of Clinical Periodontology found that oral microbiome diversity is associated with all-cause mortality, with poor dietary quality and reduced microbial diversity linked to higher death rates.
Read More: The Cause of Alzheimer’s Could Be Coming From Inside Your Mouth, Study Claims
What to Do Now
Gum disease is a chronic, systemic inflammatory condition. It silently raises the risk of heart attack, stroke, dementia, cancer, and early death. It progresses without pain in most people until significant damage has already been done. The single most effective daily intervention to prevent it costs almost nothing and takes under two minutes.
Research tracking 5,611 older adults over nearly two decades found that toothbrushing at night before bed, daily flossing, and dental visits were all significant predictors of longevity. Never flossing increased the risk of death by 30% compared to flossing every day, and skipping dental visits entirely raised the risk by 30 to 50%.
The practical takeaways are specific. Floss once daily, or at minimum once per week, to get the measurable cardiovascular benefit documented in the 2025 American Stroke Association research. Brush at night, not just in the morning. Schedule a dental cleaning twice per year. If your gums bleed when you floss, that’s not a reason to stop. Bleeding gums are a sign of active inflammation that flossing, done consistently over two to three weeks, will typically resolve. If bleeding persists beyond a month of daily flossing, ask your dentist to assess for periodontitis, which requires professional treatment to slow its progression. A 2024 study found that participants who did not receive periodontal treatment had 1.83 times the risk of death compared to those who did receive treatment, which makes the case for professional intervention when home care alone isn’t enough.
The mouth is where systemic disease often quietly begins. The fix starts between your teeth.
Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis, or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.
AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.
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