Open Wide
A new 2026 aging biomarker that lives on your tongue, an aggressively underrated daily tool, and why your mouthwash may be working against you.
For most of the past decade, anyone interested in longevity has been told to obsess over the gut microbiome. Fiber, fermented foods, probiotic strains with three Latin names…the colon got all the attention, the science, and the supplement aisle.
The mouth, meanwhile, has been treated mostly as a doorway. Brush twice a day, floss if you remember, see your dentist twice a year, get on with your life.
But now, a 2026 paper in Nature Communications has changed all that. A team led by researchers at the National Institutes of Health used data from nearly 6,000 adults across two NHANES cohorts plus an independent validation cohort to ask a deceptively simple question: can the bacterial community in your mouth predict how you are aging biologically?
The answer, it turns out, is yes. And the score they built predicts not only mortality…but frailty, cancer risk, and heart attack risk, all independent of every other risk factor they could throw into the model.
The new metric is called the Oral Microbiome Aging Acceleration Score, or OMAA. (Say it aloud. The acronym, by what I have to assume is a happy accident, requires you to open your mouth wide to pronounce it…articulatory iconicity, the linguists call it: the rare case of a word performing itself.)
The good news is that you have never heard of it because it is genuinely new science. The actionable news: a $5 tool in your medicine cabinet is one of the few things shown to improve it.
Let’s get into it.
The OMAA score explained
Here’s how they came up with the score and its implications on health.
Researchers identified 64 distinct groups of bacteria in the mouth that shift in predictable ways as people age…some species decline, others bloom. Feeding this data into a machine learning model produces a “biological age” estimate for each person’s mouth, derived entirely from its microbial signature.
They then subtract that biological age from the person’s chronological age, and that’s the OMAA score: positive means your mouth is biologically older than you are, negative means it is younger.
The results, after adjusting for age, sex, race, BMI, smoking, and other standard confounders:
For every notch the OMAA score climbed, the risk of dying from any cause rose about 5 percent.
Same 5 percent jump for becoming frail later in life, meaning loss of strength, balance, and resilience as you age.
Higher scores tracked with declining kidney function.
When researchers plugged the OMAA score into existing cancer risk calculators, the calculators got better at predicting who would develop cancer.
Same improvement for predicting heart attacks; the score made existing tools more accurate.
The 5 percent figure seems small until you realize it’s linear. A person whose mouth is 10 OMAA units older than expected carries about a 50 percent higher mortality risk than someone with a neutral score, holding everything else constant.
Three of those bacterial groups did most of the predictive work in the OMAA model:
Rothia: a friendly background species that thrives in healthy mouths and tends to decline with frailty.
Scardovia: linked to altered carbohydrate metabolism, tends to rise with sugar exposure.
Filifactor: a marker of periodontal inflammation, higher in gum disease.
These three are the “fingerprints” of an aging mouth and are the groups the model uses most. In the next section, you’ll meet a different cast of characters: Porphyromonas gingivalis as the keystone bad actor doing the most direct systemic damage, and Streptococcus salivarius and Lactobacillus reuteri as the probiotic species with the best evidence for what you’ll want to add back deliberately.
In plain English: the bacterial community living in your mouth right now is a measurable aging biomarker that predicts your mortality, your frailty, and your odds of heart attack and cancer, independent of everything else your doctor measures.
What else OMAA is saying?
Three pathways are now well-mapped, and each one connects oral bacteria to a major chronic disease of aging.
Pathway 1: The mouth-to-brain pipeline
The leading bad actor in your mouth is Porphyromonas gingivalis (P. gingivalis), the keystone of chronic gum disease. P. gingivalis produces enzymes called gingipains that chew through human proteins, including the proteins that hold cells together in the gums.
Beyond the gums, P. gingivalis DNA has also been found in the brains of Alzheimer’s patients, and gingipain enzymes have been detected in both the brain tissue and the cerebrospinal fluid of people with cognitive decline, often before clinical Alzheimer’s is diagnosed. The bacteria appear to cross the blood-brain barrier, set up shop in brain tissue, and contribute to amyloid plaque and tau tangle formation.
A 2025 review in Frontiers in Immunology even went so far as to classify P. gingivalis as a possible trigger of neurodegenerative disease, not just a passive finding of it. Small-molecule gingipain inhibitors are in clinical trials specifically as an Alzheimer’s intervention.
A note on origination and direction: P. gingivalis originates in the mouth. It does not live in soil, water, or food; it lives in human mouths and spreads between people through saliva. The mouth is its primary niche, and every documented instance of P. gingivalis at a more distant body site (arterial plaque, brain tissue, infected joint) traces back to the mouth.
Pathway 2: The mouth-to-heart pipeline
Periodontal disease is independently associated with cardiovascular disease, atherosclerosis, and heart attacks. The mechanism is partly inflammatory: P. gingivalis and a handful of other oral pathogens release lipopolysaccharides and inflammatory cytokines into the bloodstream every time you chew or floss with diseased gums. Chronic, low-grade systemic inflammation is the underlying biology of atherosclerosis, and the mouth is a steady source of it
But there is a second, more elegant pathway that rarely makes it into the dental-aisle conversation, and it is the reason your mouthwash may be misleading you.
Pathway 3: The mouth-as-nitric-oxide-factory
Your tongue, specifically the back of it, is colonized by nitrate-reducing bacteria that perform an essential metabolic conversion: they take dietary nitrate (from leafy greens, beets, etc.) and convert it to nitrite, which your body then converts to nitric oxide. Nitric oxide is the molecule that relaxes blood vessels, lowers blood pressure, and supports endothelial function across your entire vascular system. (Callback to this post…your mouth and nose work together!)
Without these specific oral bacteria, the conversion does not happen. Your blood pressure goes up. Your endothelial function suffers.
In a notable trial, healthy adults rinsed twice daily with chlorhexidine (the antiseptic in many prescription and “extra strength” mouthwashes) for 7 days. The result: a 90 percent reduction in oral nitrite production, a 25 percent reduction in plasma nitrite, and a 2 to 3.5 mmHg increase in systolic blood pressure, sustained for the duration of the rinse. A 2024 follow-up showed the same effect after a single use, with blood pressure remaining elevated for at least six days.
To put this in perspective, persistent elevations of 2 to 3 mmHg are associated with a 7 to 10 percent increase in stroke risk over time. The mouthwash you use to be more hygienic may be acting as a low-grade, chronic blood-pressure medication, except in the wrong direction.
In plain English: your tongue is part of your cardiovascular system. The bacteria there are doing an important job. Antiseptic mouthwash, used daily, kills the workers, and it’s your blood pressure that pays.
What raises your OMAA score (the wrong direction)
Untreated periodontal disease. The single biggest mover. If your gums bleed regularly when you floss, that is the signal to act.
Sugar exposure, particularly between meals, which feeds Streptococcus mutans and Scardovia (one of the three “aging” genera in the OMAA paper).
Smoking and vaping. Dramatically shifts microbiome composition, increases pathogen load, reduces beneficial bacteria.
Dry mouth, whether from medications (antihistamines, antidepressants, blood pressure drugs) or from mouth breathing at night. Saliva is antimicrobial; less saliva means a more pathogen-friendly environment.
Daily chlorhexidine mouthwash. See above.
Skipping flossing. The plaque between your teeth is where periodontal disease begins.
What lowers your OMAA score (the right direction)
Tongue scraping. A $5 stainless steel U-shape, used first thing in the morning, before food or drink. One trial found tongue scraping reduced volatile sulfur compounds by 75 percent compared to 45 percent with brushing alone. VSCs are not just the source of bad breath; they are a proxy for the anaerobic pathogen load (Fusobacterium, P. gingivalis, Treponema) growing on the tongue overnight. Scrape five to ten passes, rinse the scraper, and you have physically removed the entire biofilm community that those bacteria were hiding in.
Oil pulling. Swishing a tablespoon of coconut or sesame oil for 10 to 20 minutes. Modest, but real: a 2023 meta-analysis showed oil pulling significantly improved gingival inflammation scores. The mechanism is mechanical (oil traps lipid-membrane bacteria) and possibly mildly anti-inflammatory. Worth trying.
Flossing or interdental brushes, daily. By far the strongest evidence base, it removes the biofilm between teeth where periodontal disease starts.
Diet rich in polyphenols and fiber. Green tea, berries, leafy greens, cocoa flavanols, olive oil. Polyphenols inhibit S. mutans and shift the microbial balance towards beneficial. Fiber feeds the short-chain-fatty-acid-producing oral bacteria associated with biological-age advantage in older adults.
Targeted oral probiotics. Two strains with the strongest evidence:
Streptococcus salivarius K12 and M18. Best evidence for halitosis and for inhibiting periodontal pathogens. Available over the counter as lozenges…brand names include BLIS, Therabreath, and Burst Oral Probiotics. The irony: they may colonize better if you do a 3-to-7-day chlorhexidine rinse first to “wipe the slate,” then introduce the probiotic.
Lactobacillus reuteri DSM 17938 or ATCC PTA 5289. Best evidence specifically for gum disease. Multiple trials showed reduced gum bleeding, reduced pocket depth, and direct reductions in P. gingivalis. Available as lozenges or chewing gum.
Replacing antiseptic mouthwash with a nitrate-preserving alternative. Skip chlorhexidine, hydrogen-peroxide, and “antibacterial” alcohol-based mouthwashes for daily use. These do have a place though; use them for short courses after dental procedures. For everyday use, plain water rinses or a non-antimicrobial saline rinse keep the nitrate-reducing bacteria intact.
Nasal breathing at night. Mouth breathing dries the oral cavity, suppresses saliva, and shifts the microbial environment toward pathogens. This is the part of the story that connects mouth biology back to sleep and breathing, which is why it got its own post.
In plain English: the highest-leverage daily tools are the basics: brush, floss, scrape your tongue, eat the plants, skip the antiseptic mouthwash unless you have a specific reason to use it, and consider an oral probiotic lozenge if you have any history of gum issues or chronic bad breath. Six dollars and four minutes, mostly.
A practical five-minute morning protocol
If you wanted to act on this today, here is a four minute daily routine that costs almost nothing and is supported by the evidence:
Wake up, do not eat or drink yet. The overnight biofilm is still in place.
Tongue scrape, 5 to 10 passes from back to front, rinsing between. 30 seconds.
Brush for two minutes with a soft brush and a fluoride or hydroxyapatite toothpaste.
Floss or use interdental brushes, one minute.
Rinse with plain water, not antiseptic mouthwash, unless your dentist has specifically prescribed one short-term.
Optional: a Streptococcus salivarius K12/M18 lozenge for halitosis or post-cleaning, or L. reuteri if you have a history of gum disease. Use after brushing, not before, so it has clean surfaces to colonize.
In the evening, repeat the brushing and flossing. Skip the tongue scrape at night, unless you love it, want it, need it.
For people with diagnosed gum disease: see a periodontist, get a deep cleaning if indicated, and consider a short course of chlorhexidine (the BP-raising trade-off is acceptable for acute infection control) followed by oral probiotic introduction. This is one of the few cases where the “wipe and reseed” strategy works.
A note on testing and back to OMAA
Direct-to-consumer oral microbiome testing exists. Companies like Bristle Health and Viome offer salivary microbiome panels for $100 to $300. If you’re a data and “score” type of person, go for it! But I can save you the money: they are not yet clinically validated for predicting OMAA scores or longevity outcomes, and the advice they generate is mostly the advice in this post. But given the speed of the science, a validated home test is probably hitting the market within two years.
In Case You Skimmed
A 2026 Nature Communications paper introduced the Oral Microbiome Aging Acceleration (OMAA) score, a new biological-age metric derived entirely from the bacterial community in your mouth.
Each unit higher predicts about five percent higher mortality and frailty risk, and improves cancer and heart-attack risk prediction independently of all the standard inputs.
The main mechanistic pathways from mouth to body:
P. gingivalis → Alzheimer’s (bacteria found in AD brain tissue)
oral inflammation → cardiovascular disease
nitrate-reducing bacteria → nitric oxide → blood pressure regulation
Antiseptic mouthwash (chlorhexidine, hydrogen peroxide) kills the nitrate-reducing bacteria your blood vessels need; daily use raises systolic blood pressure by 2 to 3.5 mmHg.
Highest-leverage daily interventions:
tongue scraping (75 percent VSC reduction vs 45 percent for brushing alone)
flossing
a polyphenol-rich diet
selective use of oral probiotics (S. salivarius K12/M18 for halitosis, L. reuteri for gum disease).
The whole protocol takes about four minutes a day and costs about six dollars in tools.
The dental hygiene routine you learned at six years old turns out to be one of the highest-leverage interventions in longevity medicine. The marketing for the last forty years has pushed us toward more aggressive mouthwashes and whitening rinses, but the biology has been pushing back the whole time.
Open wide, scrape your tongue, skip the chlorhexidine, and check on your gums by next Monday.
See you then,
Susan
Longevity in the Wild
My dear friend and fellow Substacker Six Pics I Clicked // Ana Gambuto asked me if being knocked out for surgery counts as sleep. It is a wonderful question, and the answer is, sadly, no. Sleep is an active, cyclical process; your brain runs through distinct stages every 90 minutes, each one doing a specific job. REM consolidates memory and processes emotion. Deep NREM releases growth hormone and flushes metabolic waste from your brain through the glymphatic system. Anesthesia does none of this. It is more like a controlled pharmacological coma: a global suppression of brain activity with the sleep architecture turned off. Which is why you can come out of four hours of surgery feeling flattened, and out of four hours of real sleep feeling somewhat human. So no, not the same as sleep. Still, as far as ways to spend four hours in a hospital gown, remarkably restful in spirit if not in fact.