Last week I shared my personal longevity must‑haves. The response was overwhelming—many of you shared stories of living with chronic illness, caring for parents with dementia, or simply wanting to stay healthy for your kids and grandkids. Others sent sharp questions about the science behind longevity.
Reading through it all, I saw the same themes come up again and again. That’s what I want to answer today.
1. What’s the habit that makes the biggest difference?
My answer: sleep. If you’re not sleeping well (emphasis on the word “well”) nothing else moves the needle. This is why I called my book “The 8-Hour Sleep Paradox” — people get their eight hours and think they’re done, when that couldn’t be further from the truth.
Why is a dentist talking about sleep? Because how you sleep depends on how your mouth and jaw developed as a child.
Dentists are actually trained in this. The American Academy of Dental Sleep Medicine (AADSM) exists to help dentists recognize and treat sleep-disordered breathing, because the shape of your jaws, how your teeth fit together, and where your tongue rests can all affect whether your airway stays open at night.
This isn’t fringe—it’s accepted, evidence-based care. Which is why I say often…
If your dentist doesn’t ask you about your sleep, it’s time to find a new dentist.
After sleep, spermidine (link to the one I take) and C15:0 supplements are the two I never drop, specifically for longevity. They address cellular aging directly—autophagy and membrane strength.
2. Why We Struggle to Stick With Habits (and How to Fix It)
Most people don’t struggle with knowing what to do. They struggle with doing it, consistently. That’s where the real longevity work happens.
One reader told me: “The problem is execution. I know many of these things, but I can’t stick with them.”
I’ve seen this in patients and in my own life. One story I’ve told for decades: if flossing feels overwhelming, start with just one tooth. That impossibly low bar is hard to fail at, and over time the habit grows—two teeth, then three, until the whole mouth gets done.
The same psychology applies to any longevity habit.
The solution is not to pile on more. It’s to choose fewer levers and reduce friction:
- Pick one non-negotiable and make it ridiculously easy and small (i.e. floss one tooth).
- Stack a new habit onto an existing one (walk right after dinner, tape your mouth right before bed).
- Track your wins—consistency compounds.
3. Your Supplement Questions, Answered: Magnesium, Spermidine, C15:0, Omega-3s
I got dozens of questions about supplements. Some of the most common:
- Is it safe to take magnesium if your levels are normal?
Yes. Blood tests don’t tell the full story. And most of us are still lower than is optimal, even if serum levels look “normal.” Magnesium supports over 300 enzymatic reactions, calms the nervous system, regulates blood pressure, and improves sleep depth. Recent 2024 reviews link higher magnesium intake with lower all-cause mortality and reduced risk of dementia and cardiovascular disease. I take this one daily because it’s the best on the market. - Is spermidine gluten-free?
It depends on sourcing. I use a gluten-free one. You won’t get enough from food alone—most studies suggest supplementation if you want reliable autophagy benefits. - Is C15:0 just another fish oil?
No. C15:0 is a trace fatty acid that strengthens aging cell membranes. It complements omega-3s but works differently—think of it as restoring cell architecture, not just reducing inflammation. (Link to the one I take) - Do longevity supplements mess with hormones?
There’s no evidence that spermidine or C15:0 disrupt hormones. Most concern online is with compounds like resveratrol or rapamycin, which act on pathways that can overlap with hormone regulation. Spermidine and C15:0 have clean safety profiles in current research. - Do I need both omega‑3s and C15:0?
Yes—they target different pathways. Omega‑3s reduce inflammation and support brain/heart. C15:0 stabilizes cell membranes and activates AMPK/PPAR for metabolic resilience. - What’s the best time of day to take spermidine?
Research is early, but because spermidine supports autophagy, many take it in the morning or during a fasting window. Consistency is more important than timing. - Can I combine C15:0 with omega‑3s?
Yes. Studies suggest they are complementary: omega-3s reduce inflammation, while C15:0 strengthens membranes and improves metabolic signaling. - Does spermidine work right away?
No. Autophagy is a long‑term process. Benefits accumulate over months. Human trials show measurable improvements in resilience markers after consistent use. - What’s unique about C15:0 compared to other fatty acids?
It’s a trace odd‑chain saturated fatty acid. Unlike most saturated fats, it’s linked to lower inflammation, improved cell repair, and greater metabolic stability. - Can omega‑3s replace spermidine?
No. Omega‑3s and spermidine work on different longevity pathways. One supports inflammation control, the other clears damaged proteins and organelles.
4. Oral Health = Longevity Medicine
What if your dentist holds the secret to living longer?
Here’s my view:
- Oral health is systemic health. We now know that bacteria from the mouth—especially P. gingivalis, a keystone pathogen in gum disease—don’t stay confined to the gums. They can enter the bloodstream, trigger inflammation in distant organs, and have been detected in the brains of patients with Alzheimer’s disease. Studies suggest their toxins (gingipains) may damage neurons and accelerate cognitive decline. This is one of the clearest examples of the mouth–body connection: the health of your gums and oral microbiome has direct consequences for your brain, heart, and overall longevity.
- Flossing is one of the most powerful preventive tools we have. It disorganizes the pathogens that start the cascade and keeps gum disease from gaining a foothold. Once disease is advanced, you’ll need professional care too—but daily flossing is the habit that tips the odds in your favor.
- Oil pulling: swishing oil (like coconut or MCT) for 2–5 minutes. It supports the oral microbiome, and is safe. Think of it as an addition to, not a replacement for, brushing and flossing.
- Hydroxyapatite: I would only use Fluidnova brand nano‑hydroxyapatite, which is biomimetic and well‑studied for remineralization and systemic safety. It integrates naturally with enamel, supports oral health without fluoride, and has a strong safety profile. (Link to my toothpaste)
I’ll leave you with this:
The biggest risk to your longevity is feeling overwhelmed. Choose one or two levers, get them rock-solid, and only then, you can layer on more.
Hit reply with your burning questions—I may feature them in the next newsletter.
Talk soon,
Mark
P.S. May I ask for a favor? Forward this email to a loved one or fellow “health nut” — they never have to miss another newsletter if they sign up for future emails here.
Sources & Further Reading
- Induction of autophagy by spermidine promotes longevity
- Higher spermidine intake is linked to lower mortality: a prospective population-based study
- Serial measures of circulating biomarkers of dairy fat and total and cause-specific mortality in older adults: the Cardiovascular Health Study.
- Biomarkers of dairy fat intake, incident cardiovascular disease, and all-cause mortality: A cohort study, systematic review, and meta-analysis
- Magnesium and Cognitive Health in Adults: A Systematic Review and Meta-Analysis
The post What I’d tell you if we sat down to talk longevity over coffee appeared first on Ask the Dentist.
