Your Mouth and Your Gut Are.
I’ve lost count of how many times I’ve run a stool test, looked at the results, and said “when was your last dental appointment?”
The answer is almost always some version of a long pause.
With functional labs, we’re looking for one thing and the body hands us an answer for something else entirely.
What I’m actually seeing on the report
Certain microbes on a gut panel don’t always really belong in the gut. Often they belong in the mouth.
When they start showing up in high amounts downstream, it usually means more of them are making the trip than should be. Think about it…Swallowing happens about a thousand times a day, so a crowded mouth has a very reliable delivery system.
Sometimes it correlates with reflux or low stomach acid, because stomach acid is part of what keeps that traffic in check. Sometimes it’s gum inflammation that’s been present for over 2 years. If you’re still bleeding every time you floss once in a blue moon, please call your dentist.
And sometimes the person has been looking for answers for bloating for months while an overdue cleaning sat at the top of the list.
The part the research is catching up on
For a long time, the oral-gut conversation was treated as one-way traffic zone. Mouth bacteria travel down, stir up inflammation, contribute to gut conditions. Clean the mouth, protect the gut. Simple.
A new review published this year makes the case that it runs in both directions.
Gut imbalance appears to feed back up and shape what happens in the mouth. Not by sending bacteria north, but through the immune system and the metabolites your gut bugs produce.
A few parts of this study that stuck with me:
Butyrate matters up there too. Your gut microbes make short-chain fatty acids, mainly butyrate, which calm inflammation and help hold your epithelial barrier together. People with periodontitis consistently have fewer butyrate-producing bacteria in their gut. Gum tissue is lining tissue. It responds to the same signals your intestinal lining does.
Canker sores have a gut story. Recurrent mouth ulcers have been linked to SIBO and to specific gut microbial patterns. If you’ve been told to just rinse with salt water and wait, there may be more to look at.
Dry mouth and autoimmunity. Sjögren’s, which attacks the salivary glands, shows up again and again alongside reduced gut microbial diversity and more inflammatory species.
In healthy people, the two barely overlap. This is the finding I keep thinking about. In health, the mouth and the gut stay in their own lanes. The crosstalk mostly shows up when something is already off.
Where this is headed
The honest answer is that the gut-to-mouth direction is still very young. Most of the studies are observational, the mechanisms are half-mapped, and almost nobody has run a good trial on treating the gut to help the mouth.
What I expect over the next few years: looking at both sites together instead of separately, oral probiotics getting actual research behind them rather than marketing, and more dentists and gut-focused providers in the same conversation about the same patient.
Your mouth is the front door of your digestive tract. It’s a little strange that we’ve been treating it like a separate building.
What I actually tell people
See your dentist. If you can’t remember your last cleaning, that’s your answer.
Stop using antibacterial mouthwash on repeat. You have a microbiome in there doing real work, including turning dietary nitrates into nitric oxide, which supports blood pressure and blood flow. Nuking it daily is no bueno.
Pay attention to the small signals. Bleeding gums, bad breath that doesn’t respond to brushing, recurring canker sores, chronic dry mouth. Those are important to listen to.
Breathe through your nose, especially at night. Mouth breathing dries out saliva, and saliva is your mouth’s whole defense system.
Feed the bugs you want. Fiber and polyphenols support the butyrate producers in your gut, which is the same crowd linked to healthier gums.
Scrape your tongue. 30 seconds, meaningful difference.
And switch to a toothpaste that isn’t fighting your own microbiome or even systemic health. I use Boka. It uses nano-hydroxyapatite, which is a form of the mineral your enamel is already made of, so you get remineralization without the harsh antibacterial ingredients that clear-cut everything in there.
I’ve put together my full oral microbiome collection on Fullscript if you want to see what else I use and recommend: shop it here.
One last thing
If you’re doing everything for your gut and still stuck, look up. Literally.
Sometimes the missing piece can be six inches north of where everyone’s been searching.
With love (and a tongue scraper),
Dr. Jess
