I don’t talk about this as often as I probably should.
My mother had Alzheimer’s and my father had ALS with dementia. Watching parents slowly lose the core of who they are reshaped how I make everyday choices. The connection between the mouth and the brain is not abstract for me — I’ve lived it.
When I review the research on Alzheimer’s and other dementias, one clear pattern emerges: the disease process begins decades before symptoms appear. Plaques visible on scans at 75 reflect cellular damage that often started in the 40s or earlier.
The window to prevent it is now.
And here’s something many neurologists don’t emphasize: two of the most powerful, practical actions that protect the brain involve the mouth — one in the morning and one at night.
In the morning: green tea
I drink green tea every morning. It’s not just the caffeine I value but a compound called EGCG (epigallocatechin gallate). EGCG is extensively studied for neuroprotective effects and crosses the blood-brain barrier.
Several studies associate regular green tea consumption with lower rates of cognitive decline. One large Japanese cohort from 2006 followed nearly 30,000 adults and found that those who drank the most green tea had a substantially lower risk of cognitive impairment.
Less discussed is that EGCG selectively inhibits Streptococcus mutans — the primary cavity-causing bacterium — without disrupting the rest of the oral microbiome. Many common antimicrobial oral products act like a wrecking ball, harming beneficial microbes. EGCG behaves more like a scalpel.
A balanced oral microbiome matters beyond preventing cavities. Oral dysbiosis is increasingly linked to cardiovascular disease, metabolic dysfunction, and Alzheimer’s. Porphyromonas gingivalis, a key pathogen in gum disease, has been detected in brain tissue from Alzheimer’s patients. The mouth-brain axis is real, and green tea has actions on both sides of that connection.
I use a powdered green tea that is carefully sourced and processed — screened for contaminants and processed to dissolve easily — because product quality matters for consistency and safety.
At night: magnesium
Many people take magnesium for sleep, but its benefits extend further. The brain’s glymphatic system clears metabolic waste, including amyloid-beta, primarily during slow-wave sleep. If you don’t spend enough time in deep slow-wave sleep, this nightly clearance is impaired, and waste can accumulate over years.
Clinical research shows magnesium can meaningfully improve slow-wave sleep architecture — not merely helping sleep onset but increasing the depth of sleep when the brain’s cleaning occurs. I take 500 mg of a high-quality magnesium supplement 1–2 hours before bed. It’s important to choose formulations that are well-tested because different magnesium forms affect different tissues: brain, muscle, and cardiovascular systems respond to different compounds.
Taken together, morning green tea and nighttime magnesium support the oral microbiome and whole-body health. Magnesium is necessary for healthy saliva production. Saliva defends the mouth by remineralizing enamel, neutralizing acid, and keeping pathogenic bacteria in check. Subclinical magnesium deficiency can weaken these defenses, and many people are insufficient without realizing it.
EGCG’s selective action on oral bacteria and magnesium’s role in saliva production mean these simple daily habits are more than isolated supplements — they’re part of a broader strategy that begins in the mouth.
One more important point
If you have poor sleep — especially snoring, daytime fatigue, morning headaches, or reports that you stop breathing at night — no supplement will fully compensate for untreated sleep apnea. The glymphatic system cannot work effectively if your airway collapses during sleep.
Sleep apnea is often underdiagnosed in women because symptoms can present differently: persistent fatigue, difficulty concentrating, and morning headaches rather than the stereotypical daytime sleepiness. If this sounds familiar, consult a sleep specialist. Dentists trained in airway and sleep can often identify and help manage issues that traditional sleep evaluations miss.
If you haven’t yet worked with a functional dentist — a clinician who considers the mouth as part of whole-body health (airway, microbiome, sleep) — consider finding one who focuses on these connections.
My parents didn’t have access to this perspective. I can’t know if it would have changed their outcomes, but it’s why I act deliberately every morning and every night — because that’s the window I have.
I hope you use yours.
— Mark
Citations and Further Reading
The landmark study: Dominy et al. (2019) in Science Advances identified Porphyromonas gingivalis in Alzheimer’s brain tissue and linked gingipain levels to hallmark Alzheimer’s pathology, proposing a causal connection.
The doubled dementia risk: A 2019 retrospective cohort study using national insurance data reported that chronic periodontitis was associated with a substantially higher risk of developing dementia, even after adjusting for lifestyle factors.
The MRI evidence: In 2024, researchers at Columbia University’s College of Dental Medicine published an epidemiological study linking periodontitis clinical, microbial, and serological features to structural MRI changes associated with Alzheimer’s and related dementias.
The systematic literature review: Villar, Paladini & Cossatis (2024) reviewed literature from 2000–2023 and identified two main mechanisms connecting gum disease to brain pathology: systemic inflammation and direct microbial translocation into the central nervous system.
The PRISMA-guided systematic review: A 2025 review in Applied Sciences synthesized human studies on salivary and blood biomarkers and periodontal therapies in the context of Alzheimer’s and concluded periodontal disease is both a risk factor and a potential therapeutic target.
Further reading on Ask the Dentist
Can gingivitis cause Alzheimer’s disease? — A detailed breakdown of P. gingivalis research, the gingipain mechanism, and practical implications for gum care.
The Oral Microbiome & Its Impact on Every Other System in the Body — How oral dysbiosis connects to the gut-brain axis, cardiovascular disease, metabolic health, and more.
Interview: Why We Shouldn’t Ignore the Oral Microbiome — A conversation highlighting the bacterial overlap between the mouth and colon and why oral health often precedes whole-body effects.