NMN (Nicotinamide Mononucleotide)
NAD+ precursor supplement. Aims to restore declining NAD+ levels associated with aging. Unregulated supplement, not FDA-approved.
Metformin
FDA-approved diabetes medication. AMPK activator with potential longevity benefits. 60+ years of human safety data.
Side-by-Side Comparison
Raises NAD+ levels, supporting mitochondrial function, sirtuins, and DNA repair. Addresses an age-related decline.
Activates cellular energy sensor AMPK, improves insulin sensitivity, indirectly inhibits mTOR. Multiple pathways.
Small human trials show NAD+ levels increase. Some improvements in insulin sensitivity, muscle function. No longevity trials.
Diabetics on metformin live longer than non-diabetics in some studies. TAME trial for longevity pending. 60+ years of safety data.
Some mouse studies show improvements in health markers but lifespan extension data is inconsistent.
Some strains show 5% extension. Higher doses shortened lifespan. Recent meta-analyses show unreliable effects.
Sold as dietary supplement. Not FDA-approved for any indication. No prescription needed but quality varies widely.
Prescription medication approved for diabetes. Well-regulated, consistent quality. Off-label use for longevity.
No serious adverse events in short-term studies. Long-term safety unknown. Quality concerns with supplements.
60+ years of data. GI upset common. B12 depletion (supplement). Rare lactic acidosis with kidney disease.
Varies widely by brand and purity. 250-500mg/day typical dose. Third-party testing recommended.
Generic medication, extremely affordable. Available at most pharmacies. Cost is not a barrier.
Available online and in stores. No doctor needed. But quality varies, choose reputable brands with testing.
Need a doctor to prescribe. Most will prescribe for pre-diabetes/metabolic syndrome. Telehealth options exist.
Some studies suggest improved endurance and energy. NAD+ supports mitochondrial function during exercise.
Some evidence of reduced muscle adaptations and VO2max improvements. Many users skip on training days.
NMN and metformin represent two very different approaches to longevity.
**NMN** aims to restore NAD+ levels, which decline with age. The theory is compelling, NAD+ is essential for mitochondrial function, DNA repair, and sirtuin activity. However, human evidence is still limited to short-term studies showing NAD+ increases. We don't yet know if this translates to healthspan or lifespan benefits.
**Metformin** works through AMPK activation and has 60+ years of human safety data. The observational evidence is intriguing, diabetics on metformin sometimes outlive non-diabetics, but this isn't proven to extend lifespan in healthy people. It's affordable, well-studied, but may interfere with exercise adaptations.
**The honest answer:** Neither is proven for human longevity. Metformin has more safety data and costs 10x less. NMN has a compelling mechanism but less human evidence. Some people take both, reasoning they work through different pathways.
If you're choosing one, metformin is the more conservative choice with better-known risks. NMN is more experimental but easier to obtain.
Which Is Right for You?
- You want to address declining NAD+ specifically
- You prefer supplements over prescription medications
- Exercise performance is a priority (metformin may interfere)
- You have access to high-quality, third-party tested products
- You're interested in supporting mitochondrial function
- You don't mind the higher cost
- You want the option with more human safety data
- Cost is a factor ($4-15/month vs $30-150)
- You're pre-diabetic or have metabolic syndrome (proven benefits)
- You prefer FDA-regulated medications with consistent quality
- You're comfortable getting a prescription
- You want to start with the more conservative option
Important Note
This comparison is for educational purposes only and should not replace medical advice. The best medication for you depends on your individual health profile, medical history, and personal circumstances. Always consult with a healthcare provider who can evaluate your specific situation before starting any medication.
Frequently Asked Questions
Can I take NMN and metformin together?
Yes, some longevity enthusiasts take both. They work through different pathways, NMN restores NAD+ while metformin activates AMPK. There's no known negative interaction. Some researchers argue they're complementary. However, this adds cost and complexity.
Does NMN actually increase NAD+ levels?
Yes, human studies consistently show NMN supplementation increases blood NAD+ levels. The question is whether this translates to health benefits. NAD+ is definitely important, but we don't yet have evidence that supplementing it extends lifespan in humans.
Is NMN better than NR (nicotinamide riboside)?
Both are NAD+ precursors and both raise NAD+ levels. NMN is larger and was thought to not absorb directly, but recent research shows it can. NR has more human trial data currently. Many experts consider them roughly equivalent; some prefer NMN due to more recent research focus.
Why would I take metformin if I don't have diabetes?
The interest in metformin for non-diabetics comes from observational studies showing diabetics on metformin sometimes live longer than non-diabetics. The TAME trial aims to test this directly. Many longevity researchers take it for potential geroprotective effects, though this isn't proven.
What's the right dose of NMN?
Most studies use 250-500mg daily, with some going up to 1000mg. David Sinclair reportedly takes 1000mg. Start lower and assess tolerance. More isn't necessarily better, the optimal dose for longevity is unknown.
Should I take NMN in the morning or evening?
Most protocols suggest morning dosing since NAD+ is involved in circadian rhythms and energy metabolism. Taking it with food may improve absorption. Some people split doses (morning and afternoon). There's no definitive research on optimal timing.