Published February 19, 2026
Sometimes it’s good to evaluate the things we do as habits and ask why we do them. Take brushing your teeth for example. Scientific evidence shows that brushing mechanically disrupts the biofilm forming on our teeth and reduces harmful bacteria that would otherwise cause cavities. (By the way, brushing is effective whether or not we use toothpaste – toothpaste is a marketing gimmick).
But what if the mouth bacteria caused more than just cavities. What if brushing your teeth could also prevent serious neurodegenerative disorders.
Well, new research from South Korea suggests something unsettling: bacteria that cause tooth decay can escape the mouth, colonize the gut and then produce harmful metabolites, and accelerate/cause diseases like Parkinson’s!
The mechanisms are now being uncovered in this process and its eye opening. We are now seeing a clear biological pathway connecting oral health to brain health.
The Parkinson’s Puzzle
Parkinson’s disease affects about 1-2% of people over 65. It’s characterized by tremors, muscle stiffness, slowed movement, and balance problems. In fact it’s the number one fastest growing neurodegenerative disorder in the world! Some scientists say it is becoming epidemic in proportion. The later stages of the disease are devastating, including cognitive decline, weakness and swallowing difficulty.
At the cellular level, Parkinson’s involves the loss of dopamine-producing neurons in a brain region called the substantia nigra. For decades, researchers focused almost exclusively on what was happening in the brain itself.
But now scientists are looking outside the box.
Over the past ten years, study after study has shown that people with Parkinson’s have different gut bacteria compared to healthy individuals. The gut-brain connection became impossible to ignore.
What wasn’t clear was which specific bacteria mattered and how the gut changes translated into brain damage.
This new study seems to answer both questions.
An Oral Bacterium in the Wrong Place
Researchers found unusually high levels of Streptococcus mutans in the gut microbiomes of people with Parkinson’s disease. S. mutans is very common – it is the primary bacterium that causes tooth decay. It lives in our mouths – we don’t want it there but we put up with it. It thrives in a high sugar environment (hence why our modern diets increase cavity rates). The last thing we want, though, is for this bacteria to translocate to our intestines and set up shop there. But find it there we do – in very high concentrations in the guts of Parkinson’s disease patients. How did it get there? What is it doing?
First the how:
It probably got there by swallowing. We swallow saliva constantly throughout the day. Most oral bacteria don’t survive the journey through stomach acid or don’t establish themselves in the gut. But some do. The acid is our first barrier. If we are on chronic acid suppressers (think Prilosec), then we have a much higher chance of intestinal colonization.
Now what is it doing?
When S. mutans colonizes the gut, it doesn’t just sit there harmlessly. It causes some issues, serious issues. Once established in the gut, S. mutans produces an enzyme called urocanate reductase. This enzyme generates a metabolic byproduct called imidazole propionate, or ImP. ImP is not confined to the gut. The researchers found elevated levels of ImP in both the bloodstream and brain tissue of Parkinson’s patients.
This matters because ImP appears to directly contribute to neurodegeneration. Studies show it can:
– kill the important dopamine-producing neurons in our substantia nigra
– Increase brain inflammation
– and it accelerates accumulation of alpha-synuclein, the protein that clumps in Parkinson’s disease
In fact, alpha-synuclein aggregation is one of the defining features of Parkinson’s pathology. Anything that speeds up this process is concerning for sure
The Mouse Experiments That Proved Causation
To test whether this was actually causing the problem or just associated with it, researchers did elegant experiments in mice.
They introduced S. mutans into the gut of healthy mice. Also they engineered other gut bacteria to directly produce the enzyme that makes ImP.
Both results were striking. The mice in both groups of course developed elevated ImP levels in the blood and brain. This caused a cascade of events and the mice ended up losing dopamine neurons, showing increasing brain inflammation, accumulating more alpha-synuclein and then having worsening motor control.
In other words, introducing this oral bacterium—or its metabolic machinery—was enough to reproduce key features of Parkinson’s disease in previously healthy animals.
The Signaling Pathway That Connects It All
The researchers went on to try and figure out how ImP damages the brain. They think it activates a cellular signaling pathway called mTORC1.
mTORC1 is a central regulator of cellular growth, metabolism, and inflammation. When it’s excessively activated, it’s been implicated in aging, metabolic disease, cancer, and now neurodegeneration.
When researchers treated mice with an mTORC1 inhibitor (rapamycin, which protects from over-stimulation), they saw reduced brain inflammation, preservation of dopamine neurons, decreased alpha-synuclein accumulation, and improved motor function. This finding opens the door to therapeutic strategies aimed not just at the brain, but at the microbial and metabolic drivers upstream.
What This Means Practically
This research reinforces several underlying principles in pursuit of health optimization. First, chronic diseases are often systemic, not isolated to one organ. Second microbial metabolites matter, hence our microbiome matters. Three oral health is under-appreciated and could be foundational for health.
Parkinson’s may not begin in the brain. It may begin in the mouth, the gut, and the immune system years earlier.
What You Can Do Now
This research doesn’t mean brushing your teeth will for sure prevent Parkinson’s. But it strongly supports taking oral and gut health seriously as part of long-term brain protection.
Practical steps include brushing once or twice daily and flossing too. Also avoiding excessive sugar that fuels harmful oral bacteria. In addition, supporting gut health with fiber-rich whole foods is a good idea. Using long term acid blockers only if really necessary (acid reflux maybe a dietary problem and not a structural problem in some people) . Also being cautious with unnecessary antibiotics as these can upend the gut microbiome.
Questions that remain
– Does killing off strep mutans via narrow spectrum antibiotics reduce the risk of Parkinson’s?
– Could we make a drug to block ImP and prevent Parkinson’s?
– could certain oral probiotics outcompete strep mutans in the mouth and reduce Parkinson’s?
– same question for gut probiotics?
As the Bible says do not despise the day of small beginnings. Likewise small habits like brushing and avoiding a sugary beverage could mean protection for your brain.
Blessings,
Dr Ponke
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