The Longevity Protocol: What Actually Has Evidence

Longevity research is flooded with hype. Every compound gets marketed as a "breakthrough" that extends lifespan. Every supplement founder claims their product will make you live to 120. This is garbage. The reality is that longevity interventions have wildly different levels of evidence, cost-benefit ratios, and applicability. Some interventions are scientifically robust and worth doing. Others are speculative at best, dangerous at worst.

This article ranks every major longevity intervention by evidence strength, explains the mechanisms, and gives you a practical cost-benefit analysis for each. The result is a protocol based on what actually works, not what generates the best marketing.

The Evidence Hierarchy

Longevity evidence falls into tiers. Tier 1 interventions have human lifespan data (studies showing actual lifespan extension in humans). Tier 2 interventions have strong biomarker data and mechanistic plausibility in humans. Tier 3 interventions are promising in animal models but unproven in humans. Tier 4 interventions are speculative or show benefit in animals that doesn't translate to humans. Most longevity supplements you see advertised are Tier 3 or Tier 4.

Tier 1: Interventions With Human Lifespan Evidence

Exercise

Exercise is the single strongest longevity intervention. Period. Multiple large studies show that moderate-to-vigorous exercise extends lifespan by 3-7 years. Every hour of moderately intense exercise adds roughly 2 hours to your remaining lifespan. This isn't theoretical - this is direct human data from hundreds of thousands of people followed over decades.

• Effective dose: 150 minutes moderate intensity OR 75 minutes vigorous intensity per week
• Mechanism: Increases cardiovascular fitness, reduces inflammation, supports metabolic health, improves cognitive function
• Cost: Free (or cheap if you join a gym)
• ROI: Highest of all interventions

Sleep

Poor sleep is associated with 10-15 year lifespan reduction. Good sleep (7-9 hours, consistent timing) is associated with the longest lifespan. The mechanisms are clear: sleep repairs DNA damage, consolidates memories, clears metabolic waste from the brain, and resets immune function. This is as close to proven as you get.

• Effective dose: 7-9 hours nightly, consistent sleep-wake times
• Mechanism: DNA repair, immune consolidation, metabolic waste clearance, cognitive consolidation
• Cost: Free
• ROI: Highest possible

Tier 2: Strong Biomarker Evidence, Likely Lifespan Effect

Metformin

Metformin is the most studied drug in longevity research. Diabetics on metformin live longer than non-diabetics, and longer than diabetics on other medications. Mechanistic studies show metformin activates AMPK, reduces mTOR signaling, improves mitochondrial function, and reduces senescent cell accumulation. The lifespan effect in humans is inferred but strong.

• Dose: 500-1000 mg twice daily
• Considerations: Requires medical supervision; risk of B12 deficiency with long-term use; GI side effects common; contraindicated with kidney disease
• Cost: Pennies per day
• ROI: Very high if you have metabolic dysfunction or family history of metabolic disease

Caloric Restriction (or Time-Restricted Feeding)

Caloric restriction extends lifespan in every organism studied, from yeast to primates. Humans on long-term caloric restriction show improved cardiovascular biomarkers, reduced cancer risk, and reduced diabetes risk. The lifespan extension in humans hasn't been proven directly yet (the studies would take 100 years), but the biomarker evidence is compelling.

• Effective dose: 10-25% caloric reduction, OR 16:8 intermittent fasting daily
• Mechanism: Activates AMPK, reduces mTOR, improves mitochondrial autophagy, reduces inflammation
• Cost: Negative (you spend less on food)
• Challenges: Requires discipline; metabolic adaptation diminishes benefits over time; hunger adapts slowly

Tier 3: Promising Animal Data, Some Human Mechanistic Evidence

Rapamycin (Intermittent, Low-Dose)

Rapamycin is an mTOR inhibitor that extends lifespan in mice, rats, and primates by 10-30%. It's FDA-approved for organ transplant immunosuppression at high doses. At very low doses (1-3 mg weekly), it appears to have longevity benefits with fewer side effects. Human data is limited, but mechanistic evidence is strong - it reduces senescent cells, improves immune function, and inhibits the aging-driver mTOR pathway.

• Dose: 1-3 mg once weekly (much lower than transplant doses)
• Considerations: Requires medical supervision; risks include immunosuppression, mouth ulcers, lipid elevation; not FDA-approved for longevity use
• Cost: $100-300/month
• ROI: Speculative but mechanistically sound if lifespan data eventually emerges

NAD+ Precursors (NMN, NR)

NAD+ is a critical coenzyme for mitochondrial function and DNA repair. NAD+ levels decline with age. Supplementing with NAD+ precursors (nicotinamide mononucleotide or nicotinamide riboside) boosts NAD+, activates sirtuins (longevity-regulating enzymes), and improves mitochondrial function in animal models. Human studies show improved metabolic health, but lifespan data doesn't exist yet.

• Dose: NMN 250-500 mg daily, OR NR 250-1000 mg daily
• Mechanism: Restores NAD+, activates sirtuins, improves mitochondrial function and DNA repair
• Cost: $50-150/month depending on form and purity
• Quality concern: Many cheap NMN/NR supplements are poorly characterized; use brands with third-party testing

Tier 3.5: Senolytics (Emerging Evidence)

Dasatinib + Quercetin (the "D+Q" Protocol)

Senolytics are compounds that kill senescent cells - aging cells that no longer divide but accumulate with age, driving inflammation and tissue dysfunction. Dasatinib (a tyrosine kinase inhibitor) plus quercetin (a flavonoid) effectively clear senescent cells in human tissue. One small human trial showed improvement in physical function in older adults. Animal studies show lifespan extension, but human data is minimal.

• Dose protocol: Dasatinib 100 mg once, then quercetin 500 mg 3x daily for 2 days, repeated monthly or quarterly
• Mechanism: Senescent cell clearance, reduced inflammatory signals from aged tissue
• Considerations: Dasatinib requires medical prescription; potential side effects include GI upset and QT prolongation (requires ECG monitoring)
• Cost: $200-500 per treatment cycle
• ROI: Very high IF senescent cell accumulation is a major driver of your aging (which it likely is), but human proof is still emerging

GlyNAC (Glycine + NAC)

GlyNAC is a combination supplement designed to restore the body's most abundant antioxidant, glutathione. Glutathione declines with age; supplementing it directly doesn't work (it's not absorbed). But glycine plus N-acetylcysteine together are substrates for glutathione synthesis. A Stanford study showed GlyNAC improves mitochondrial function, metabolic health, and physical function in older adults. Very promising, but human lifespan data doesn't exist.

• Dose: Glycine 7.5 g + NAC 7.5 g daily (usually in divided doses)
• Mechanism: Restores glutathione, improves antioxidant defenses and mitochondrial function
• Cost: $30-50/month
• ROI: High if you're over 50 or have signs of accelerated aging

Tier 4: Speculative or Unproven in Humans

Resveratrol

Resveratrol activates sirtuins and extends lifespan in yeast and short-lived organisms. But human studies show minimal benefit, bioavailability is poor, and no lifespan data exists. It's promoted heavily but has weak evidence.

Spermidine

Spermidine induces autophagy in animal models and extends lifespan in some organisms. Epidemiological studies suggest higher dietary spermidine is associated with longer lifespan. But intervention trials in humans are lacking. Possibly useful, but speculative.

Pterostilbene, Fisetin, Sulforaphane

All promote cellular stress responses or senescent cell clearance in vitro or in animals. None have human lifespan data. These are Tier 4 - interesting mechanistically, but not proven.

Complete Evidence-Based Longevity Protocol

Tier 1 (Essential - Do These First)

• Exercise: 150 minutes moderate intensity or 75 minutes vigorous weekly
• Sleep: 7-9 hours nightly, consistent sleep-wake times

Tier 2 (Highly Recommended If Applicable)

• Caloric restriction or intermittent fasting: 10-25% caloric reduction or 16:8 fasting
• Metformin: 500-1000 mg twice daily (requires medical supervision, for people with metabolic dysfunction)

Tier 3 (Worth Considering, Especially After Age 50)

• NAD+ precursors: NMN 250-500 mg daily or NR 500-1000 mg daily
• GlyNAC: Glycine 7.5 g + NAC 7.5 g daily

Tier 3.5 (Emerging, Consider With Medical Guidance)

• Senolytics (D+Q): Dasatinib 100 mg + Quercetin 1500 mg monthly or quarterly (requires prescription)
• Rapamycin: 1-3 mg weekly (requires medical supervision and discussion of risk-benefit)

Cost-Benefit Summary

The Honest Truth About Longevity

Living to 120 is not realistic with current science. But living healthily to 90-95 instead of 75-80 is absolutely achievable. The interventions that do this are: exercise (non-negotiable), sleep (non-negotiable), metabolic health (through diet and/or metformin), and senescent cell management (through caloric restriction and/or senolytics). Everything else is optimizing around these core pillars.

The supplement industry wants to convince you that expensive pills are the answer. They're not. Exercise and sleep alone will extend your lifespan by 10+ years. Everything else adds years on top of that foundation.

Bottom Line

Build your longevity protocol in order: Tier 1 first (you must do exercise and sleep), then Tier 2 (metabolic health), then Tier 3 (cellular maintenance). Ignore Tier 4 entirely. This evidence-based approach eliminates hype and focuses on what actually works. The result: meaningful lifespan and healthspan extension without wasting money on speculative compounds.