Longevity Supplement Stack: NAD+ Precursors & Senolytics Evidence Protocol

Key Definitions

NAD+ (Nicotinamide Adenine Dinucleotide): A coenzyme found in every living cell, central to energy metabolism (ATP production via the mitochondrial electron transport chain) and critical as a substrate for sirtuins (SIRT1–7, longevity-associated deacylases) and PARP enzymes (DNA repair). NAD+ declines approximately 50% between ages 40 and 60 in humans, though the precise mechanisms and consequences of this decline remain an active research area.

NAD+ Precursors: Oral supplements that the body converts to NAD+:

• NMN (Nicotinamide Mononucleotide): One step upstream of NAD+ in the salvage pathway. Converted via NMNAT enzymes. Bioavailability of oral NMN debated (SlC12A8 transporter controversy).
• NR (Nicotinamide Riboside): Two steps upstream. Converted to NMN then NAD+. Strong bioavailability data in humans (Trammell et al. 2016, Martens et al. 2018).
• Niacin / Nicotinamide (NAM): Less expensive but different side-effect profiles (flushing for niacin; NAM may inhibit sirtuins at high doses). Not covered in this protocol.

Senescent Cells: Cells that have permanently exited the cell cycle but resist apoptosis, secreting a pro-inflammatory cocktail called the SASP (Senescence-Associated Secretory Phenotype). SASP includes IL-6, IL-8, MMP3, and other factors that damage neighboring tissue. Senescent cell burden increases exponentially with age and is implicated in multiple age-related diseases.

Senolytics: Compounds that selectively kill senescent cells (from Greek: geras = old age, lysis = destruction). Examples: Dasatinib + Quercetin (D+Q), Fisetin, ABT-263 (navitoclax). Distinct from senomorphics.

Senomorphics: Compounds that suppress SASP without killing senescent cells (e.g., rapamycin, JAK inhibitors). Different mechanism from senolytics. Often confused in popular media.

The Hallmarks of Aging (López-Otín et al., updated 2023): Genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, disabled macroautophagy, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, dysbiosis. Any serious longevity intervention should address one or more of these mechanistically.

Key Findings

What human evidence actually shows:

1. NMN raises NAD+ in blood — confirmed in multiple small RCTs. Whether this raises NAD+ in muscle (the relevant tissue for many aging endpoints) is contested. Yoshino et al. 2021 (Science) found improved muscle insulin sensitivity in 25 prediabetic women without detecting elevated muscle NAD+ — suggesting the benefit may not require tissue-level NAD+ restoration, or that the methodology was insufficient to detect it.

2. NR raises NAD+ in blood — consistently demonstrated (Martens et al. 2018, Nature Communications; n=30, double-blind crossover). Bioavailability well established. Functional outcomes in healthy aging remain modest.

3. GlyNAC reverses multiple aging hallmarks in humans — Kumar et al. 2021 pilot (Clin Transl Med) and Kumar et al. 2023 RCT (J Gerontol) are the most compelling human aging intervention data available for any supplement. Showed improvements in glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, muscle strength, and cognitive function in older adults.

4. Taurine declines with age in humans — confirmed across species (mice, monkeys, humans) in Singh et al. 2023 (Science). However, this is correlation, not causation. The study showed supplementation extended healthspan in mice and monkeys, and associated lower taurine with aging diseases in humans. Human supplementation RCTs for longevity do not yet exist.

5. Fisetin shows senolytic activity in humans — early. Mayo Clinic pilot (Turner et al., 2023) in older women with frailty showed signals: reductions in SASP markers (IL-6, MMPs). Not powered for efficacy endpoints. Ongoing trials (NCT06431932, “Alleviation by Fisetin of Frailty, Inflammation, and Related Measures in Older Women”).

6. Resveratrol largely disappoints — the sirtuin activation hypothesis has not replicated cleanly in humans. A 2025 meta-analysis (ScienceDirect) found no significant effect of resveratrol on SIRT1 expression or serum levels across RCTs. Bioavailability is poor without piperine. Not recommended as a first-line longevity agent.

7. Spermidine shows epidemiological and small-trial signal — dietary spermidine associated with longevity in large Austrian cohort (Kiechl et al. 2018). Supplementation is safe (Wirth et al. 2018). Randomized trial data for longevity endpoints are minimal.

The Evidence Hierarchy (Critical for This Topic)

Why You Must Read This Section

The longevity supplement space is uniquely prone to premature human extrapolation from animal models. Understanding why is essential to evaluating any claim.

The Animal → Human Translation Problem

Most mammalian longevity studies use inbred mice (C57BL/6 or HET3). These animals:

• Live 2–3 years (vs. 80+ for humans)
• Have radically different NAD+ metabolism kinetics
• Are housed in controlled environments with no lifestyle confounders
• Are often studied with interventions starting at equivalent of “middle age” (14–18 months)

Known translation failures:

• Resveratrol → Extended lifespan in C. elegans, yeast, and some mouse models. Failed to activate sirtuins directly in humans at physiological doses. GSK’s Sirtris acquisition (~$720M in 2008) produced no approved drugs.
• Alpha-lipoic acid → Impressive mouse aging data; limited human evidence for longevity endpoints.
• Antioxidants broadly → Massive preclinical promise; ATBC and SELECT trials showed null or harmful effects. Exercise-induced ROS may actually be beneficial — blanket antioxidant supplementation can blunt hormesis.

The ITP Benchmark

The NIA’s Interventions Testing Program (ITP) is the gold standard for rigorous, multi-site, blinded animal testing. Compounds are tested simultaneously at three independent sites using genetically heterogeneous HET3 mice.

ITP compounds with significant lifespan extension (as of 2024):

• Rapamycin (mTOR inhibitor) — most robust signal; 9–26% lifespan extension across multiple tests
• Acarbose — ~22% male, ~5% female lifespan extension
• 17α-Estradiol — males only
• Canagliflozin — males only
• Combination rapamycin + acarbose — synergistic

ITP failures relevant to this protocol:

• Resveratrol — no significant lifespan extension in ITP testing (Miller et al. 2011)
• Fish oil, curcumin, green tea extract — all tested; no significant effect in ITP

What the ITP teaches us: Even compounds with excellent mechanistic rationale and positive preclinical data fail in rigorous multi-site testing. Human data requirements should be higher, not lower, given the complexity of human physiology.

Evidence Grading Used in This Protocol

NAD+ Decline — The Mechanism

Why NAD+ Matters

NAD+ is required as a co-substrate by:

• Sirtuins (SIRT1–7): Deacylases that regulate gene expression, metabolism, and stress responses. Consume NAD+ per reaction — so declining NAD+ limits sirtuin activity.
• PARPs (poly-ADP-ribose polymerases): DNA damage sensors and repair enzymes. PARP1 alone may consume 60–80% of cellular NAD+ under conditions of high DNA damage — a key mechanism of NAD+ depletion in aging tissue.
• CD38: A cyclic ADP-ribose hydrolase and major consumer of NAD+. CD38 activity increases with aging due to chronic inflammation and immune cell infiltration. May be the primary driver of age-related NAD+ decline.

The Decline Curve

• Human NAD+ blood levels decline approximately 1.5–2% per year after age 30
• By age 60, NAD+ is approximately 40–60% of young-adult levels (varies by tissue and measurement method)
• Skeletal muscle, liver, and adipose tissue show the steepest declines
• Brain NAD+ decline is more modest and harder to measure non-invasively

Why Oral Boosting Is Complicated

The “oral NMN → NAD+” pipeline in humans involves:

1. Intestinal absorption (requires SLC12A8 transporter or direct conversion to NR)
2. Hepatic first-pass metabolism
3. Conversion in peripheral tissues (requires NMNAT1/2/3 enzymes)
4. Tissue-specific distribution

Yoshino et al. 2021 found that 250mg/day NMN for 10 weeks raised NAD+ in PBMCs (white blood cells) but NOT detectably in skeletal muscle via muscle biopsy — suggesting blood NAD+ measurements may not reflect what matters most functionally.

Implication: Blood NAD+ is a biomarker, not an outcome. Interpret supplement marketing (“raises NAD+ by X%”) accordingly — this refers to blood NAD+, not muscle or brain NAD+.

Key Compounds — Evidence Review

NMN (Nicotinamide Mononucleotide)

Evidence Grade: C (human biomarker data; one human RCT with functional endpoint)

Landmark Human Study: Yoshino M, Yoshino J, Kayser BD, et al. “Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women.” Science. 2021;372(6547):1224–1229. DOI: 10.1126/science.abe9985

• Design: Double-blind, placebo-controlled RCT
• n: 25 prediabetic postmenopausal women
• Dose: 250mg/day oral NMN for 10 weeks
• Key finding: Significantly improved muscle insulin sensitivity (hyperinsulinemic-euglycemic clamp) and upregulated muscle remodeling genes. NAD+ increased in PBMCs but NOT in muscle biopsies.
• Limitation: Small n, single-sex, single metabolic condition (prediabetes), short duration, no longevity endpoints

Additional Human Data (2021–2024):

• Balan et al. 2023 (Am J Physiol): NMN + exercise training improved aerobic capacity in middle-aged athletes (n=48)
• Multiple safety studies: NMN well-tolerated up to 1200mg/day. No serious adverse events in trials ≤12 weeks.
• Faverio et al. 2025 (Adv Nutr): Review of completed human trials — consistent blood NAD+ elevation; functional outcome data mixed

Oral Bioavailability Controversy: Chen et al. 2019 (Nat Metab) proposed NMN requires the SLC12A8 transporter for cellular uptake. Subsequent studies challenged whether this transporter is expressed adequately in human intestinal cells. Practical implication: NMN likely converts to NR in the intestine before absorption — meaning the metabolic pathway may be NR-equivalent, not a distinct advantage.

Sublingual/Liposomal NMN: Some manufacturers claim enhanced absorption. Human pharmacokinetic data for these formulations are limited; not yet peer-reviewed at scale.

Recommended dose range: 250–500mg/day (morning, with or without food)

NR (Nicotinamide Riboside)

Evidence Grade: B (multiple human RCTs, blood NAD+ elevation confirmed; functional outcomes modest)

Key Human Studies:

1. Trammell et al. 2016 (Nat Commun): First demonstration that oral NR elevates human NAD+ and metabolome. n=12, crossover design. 300mg NR raised blood NAD+ by ~40%.

2. Martens et al. 2018 (Nat Commun): Double-blind, randomized, crossover, n=30 healthy middle-aged and older adults. 500mg NR twice daily (1000mg/day). NAD+ elevated ~60% in blood. Modestly reduced aortic stiffness (systolic blood pressure −3.9 mmHg). No significant effect on most other endpoints. Best evidence for NR safety and blood NAD+ elevation.

3. Pirinen et al. 2020 (Cell Metab): NR in mitochondrial myopathy patients; no meaningful benefit. Demonstrates that NAD+ boosting is not a universal fix.

NR Safety:

• Well-tolerated across multiple studies
• 300–2000mg/day studied without serious adverse events
• May cause flushing at high doses (less than niacin)
• Long-term (>1 year) safety data in humans limited

Recommended dose range: 300–500mg/day (morning)

NMN vs NR — Which to Choose?

Verdict: Both raise blood NAD+. NR has more robust human bioavailability data and is less expensive. NMN has one high-quality functional RCT (Yoshino 2021). Neither has demonstrated lifespan extension or reversal of major aging hallmarks in humans. Choose based on cost and availability. Do not pay premium pricing for “sublingual” or “liposomal” formulations without demanding peer-reviewed pharmacokinetic data.

Fisetin (Intermittent Senolytic)

Evidence Grade: C→B transitional (strong preclinical; early human pilot data; ongoing Mayo trials)

Mechanism: Fisetin is a polyphenol (flavonol) found naturally in strawberries, apples, persimmons. Senolytic activity via inhibition of BCL-2/BCL-XL anti-apoptotic proteins — forcing senescent cells (which overexpress these proteins for survival) into apoptosis.

Landmark Preclinical Study: Xu M, et al. “Senolytics improve physical function and increase lifespan in old age.” Nat Med. 2018;24:1246–1256. DOI: 10.1038/s41591-018-0092-9

• Fisetin extended lifespan by 10% in old mice when started late in life
• Reduced senescent cell burden, SASP markers, and physical decline
• This is the mechanistic foundation for human trials

Human Data — Mayo Clinic Trials:

• Turner et al. 2023 (EBioMedicine): Phase 1/2 pilot in older women with frailty. 20mg/kg/day oral fisetin × 2 consecutive days. Measured senescent cell markers (p16^INK4a, p21^CIP1, SASP cytokines including IL-6, MMP-3). Preliminary results showed reduction in some SASP markers. Not powered for efficacy; exploratory endpoints only.
• NCT04210986 (AFFIRM) — Fisetin in frailty/inflammation in older women. Ongoing.
• NCT06431932 — Pilot trial of fisetin in healthy volunteers. Ongoing.

⚠️ Critical Dose Caveat: The “Mayo Protocol” dose of 20mg/kg for 2 consecutive days for a 70kg person = 1,400mg/day for 2 days. This is dramatically higher than typical supplement doses (100–500mg/day). This dose comes from preclinical scaling, NOT from established human efficacy data. The translation from mouse to human dosing for senolytics is biologically uncertain.

Commercial fisetin supplements at 100–500mg/day have no clinical evidence for senolytic activity in humans at those doses.

Recommended approach if self-experimenting:

• 500–1000mg/day for 2 consecutive days, monthly (pragmatic dose reduction from 20mg/kg; acknowledge no human efficacy data at this dose)
• Taken with food (fat increases absorption)
• Do NOT take continuously — senolytic mechanism requires pulsed dosing

Quercetin (with Dasatinib Context)

Evidence Grade: D (for quercetin alone as senolytic; senolytic evidence requires dasatinib combination)

Background: The most-studied senolytic combination in humans is Dasatinib + Quercetin (D+Q), originating from Mayo Clinic computational screening (Zhu et al. 2015). Dasatinib (a BCR-ABL kinase inhibitor) and quercetin act synergistically to clear senescent cells.

Key Human Studies (D+Q combination):

• Hickson et al. 2019 (EBioMedicine): Open-label pilot, n=9 patients with idiopathic pulmonary fibrosis. D+Q (100mg dasatinib + 1250mg quercetin) × 3 days/week × 3 weeks. Reduced senescent cell markers (p16^INK4a, p21^CIP1) in adipose tissue and skin biopsies, improved physical function. Open-label, no control group, small n.
• Nambiar et al. 2023 (Nat Aging): D+Q in Alzheimer’s disease — CSF biomarker changes. Phase 1.

⚠️ IMPORTANT — Dasatinib is Rx Only: Dasatinib is an FDA-approved cancer drug (Sprycel, ~$15,000/month). It has serious side effects including pleural effusion, cardiac events, and immunosuppression. It is not appropriate for self-administration as a longevity supplement. Any context in which you read “D+Q protocol” for longevity requires medical supervision.

Quercetin alone: Quercetin without dasatinib has modest anti-SASP activity in vitro but lacks demonstrated senolytic efficacy in human studies. Quercetin is an antioxidant and anti-inflammatory agent with its own evidence base for cardiovascular health, but this is distinct from senolytic activity.

If using quercetin:

• Standard dose: 500–1000mg/day
• Take with piperine (5–10mg) for bioavailability (+20%)
• Do not expect senolytic effects from quercetin alone based on current evidence

Resveratrol

Evidence Grade: D→E (preclinical promise; failed to replicate in human RCTs; ITP failed)

The Sinclair Hypothesis: David Sinclair’s lab (Harvard) proposed in the 2000s that resveratrol activates SIRT1 via conformational change, mimicking caloric restriction. High-profile papers in Nature (2006) showed resveratrol extended lifespan in obese mice. This sparked a decade of enthusiasm and significant pharmaceutical investment.

The Collapse of the Narrative:

1. Pfizer/ITP replication failure (2011): Miller et al. tested resveratrol in ITP mice. No significant lifespan extension in non-obese genetically heterogeneous mice. The original mouse data may have been an artifact of the specific obese mouse model used.

2. GSK/Sirtris failure: GSK acquired Sirtris Pharmaceuticals for ~$720M in 2008. Multiple resveratrol-analogue clinical trials (SRT2104, SRT2379) were terminated due to lack of efficacy.

3. Mechanism dispute: Scrutton et al. (2010) argued the SIRT1 activation was an artifact of the fluorescent peptide substrate used in assays — not physiologically relevant. This remains contested but seriously undermined the mechanism.

4. 2025 Meta-analysis: Systematic review of RCTs on resveratrol and SIRT1 expression (ScienceDirect, 2025): No significant impact on SIRT1 gene expression (SMD = 0.05, p=0.73), protein expression, or serum levels.

What Resveratrol DOES:

• Antioxidant activity (moderate)
• Anti-inflammatory (some evidence in metabolic disease)
• Cardiovascular: Mixed RCT results; some evidence for reduced oxidative stress in T2DM
• Bioavailability: Extremely poor (~1% oral bioavailability without piperine; with piperine, absorption increases ~229%)

Verdict: Resveratrol is not a longevity supplement supported by current human evidence. The mechanism that drove interest has failed to validate. If taking for anti-inflammatory cardiovascular effects (separate evidence base), combine with piperine. Do not expect sirtuin activation or longevity benefit.

Resveratrol dose if using: 100–500mg/day with 5mg piperine. Note: Resveratrol + anticoagulants (warfarin, clopidogrel) — potential interaction via CYP2C9 inhibition. Medical review required.

Glycine + NAC (GlyNAC)

Evidence Grade: A (multiple human RCTs; multiple aging hallmarks addressed; independent replication)

This is the strongest human evidence in this entire protocol. Do not let the humble ingredients (amino acids) diminish your assessment of the data quality.

Mechanism:

• Glutathione (GSH): The body’s master antioxidant. Declines ~50% between young and old age. Cannot be effectively supplemented directly (poor oral absorption). Must be synthesized from precursors.
• GSH synthesis requires glycine AND cysteine (from NAC = N-Acetyl Cysteine). In aging, both are deficient — creating a bottleneck.
• GlyNAC addresses both limiting substrates simultaneously.

Key Human Studies (Sekhar Lab, Houston Methodist/Baylor):

1. Kumar et al. 2021 (Clin Transl Med): Pilot RCT, n=8 old + 8 young adults. GlyNAC 100mg/kg/day × 24 weeks. Results: Corrected glutathione deficiency, improved oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, genotoxicity, muscle strength, and cognition. First human study showing multi-hallmark reversal with a supplement.

2. Kumar et al. 2023 (J Gerontol A): Randomized clinical trial, n=84 older adults, 16 weeks. Confirmed: improved glutathione levels, oxidative stress, mitochondrial function, physical function, body composition. Effect sizes were clinically meaningful.

3. Safety: GlyNAC well-tolerated across all studies. Both glycine and NAC have decades of safety data individually (NAC is used medically for acetaminophen overdose).

Why This Matters: GlyNAC is the only supplement in this protocol that has demonstrated reversal of multiple canonical hallmarks of aging in a proper randomized human trial, not just biomarker changes.

Recommended dose:

• Glycine: 1.33g per 10kg body weight (for 70kg: ~9.3g/day) — taken as powder in water
• NAC: 0.81g per 10kg body weight (for 70kg: ~5.7g/day)
• Alternatively (pragmatic dose): Glycine 9g/day + NAC 600–1200mg/day (commercially available dosing)
• Timing: Morning, can split into 2 doses. Glycine improves sleep quality — some prefer evening dose.

Note on “Glycine alone”: Some evidence suggests glycine supplementation (3–5g/day) has independent benefits on sleep quality, insulin sensitivity, and collagen synthesis. Taking glycine alone is a lower-cost option with its own rationale.

Taurine

Evidence Grade: C→B transitional (declining levels in humans confirmed; mouse + monkey lifespan data; no human longevity RCT)

Key Study: Singh P, et al. “Taurine deficiency as a driver of aging.” Science. 2023;380(6649):eabn9257. DOI: 10.1126/science.abn9257

What the study showed:

• Taurine blood concentrations decline with aging in mice, monkeys, AND humans (~80% lower in 60-year-old humans vs. young adults)
• Taurine supplementation extended healthspan in middle-aged mice by 10–12% and lifespan by 10–12%
• In monkeys, taurine reduced bone loss, improved energy levels, reduced fat mass
• In humans: cross-sectional association between lower taurine and aging-related diseases (not causal)

⚠️ Critical Limitation: The human data in Singh et al. is observational and cross-sectional — showing that older people have less taurine, not that supplementing taurine makes them younger. A separate 2025 study (PMC12507425) found no difference in taurine levels between physically active and inactive older adults, challenging the “taurine deficiency drives aging” narrative in humans specifically.

No human longevity RCT exists for taurine. The Science 2023 paper is important mechanistically but does not provide the same level of evidence as GlyNAC trials.

Taurine Safety: Extensively established. Present in energy drinks at 1–2g/dose; 3g/day is a common supplement dose with no known safety concerns. Long history of clinical use.

Recommended dose: 1–3g/day (morning or split doses). Low risk, potential benefit, reasonable to include while awaiting RCT data.

Spermidine

Evidence Grade: C (epidemiological signal; small human safety/tolerability trial; mechanistic animal data)

Mechanism: Natural polyamine found in high concentrations in wheat germ, aged cheese, soybeans, mushrooms. Activates autophagy (cellular self-cleaning mechanism — inhibits mTOR pathway). Autophagy is one of the confirmed hallmarks-of-aging mechanisms, and spermidine is one of the few orally bioavailable autophagy inducers.

Human Evidence:

1. Kiechl et al. 2018 (Am J Clin Nutr): Large prospective cohort (n=829, Bruneck Study). Higher dietary spermidine intake associated with reduced cardiovascular mortality and all-cause mortality over 20-year follow-up. Observational; confounding possible (spermidine-rich diet = Mediterranean-adjacent).

2. Wirth et al. 2018 (Aging): Safety and tolerability study — wheat germ extract spermidine in older adults with subjective cognitive decline. Safe and well-tolerated. Trend toward cognitive improvement (not powered for efficacy).

3. Schroeder et al. 2021 (GeroScience): Spermidine supplementation improved memory in older adults with subjective memory decline. n=100, RCT. First adequately powered trial — cognitive endpoint.

Recommended dose: 1–3mg/day from wheat germ extract (standardized to spermidine content). Alternatively, increase dietary sources (wheat germ, aged parmesan, green peas, mushrooms).

Note: Most commercial “spermidine supplements” contain 1–2mg spermidine per capsule. This is a relatively small dose compared to what high-spermidine diets provide.

Dosing Schedules

Daily Stack (Evidence-Based Core)

What’s NOT in the daily stack:

• Resveratrol: insufficient evidence; not recommended as longevity agent
• Quercetin: include if desired for anti-inflammatory benefit (500mg/day), but not as senolytic
• Fisetin: intermittent use only (see below)

Intermittent (Senolytic) Stack

Rationale: Senolytics work by clearing existing senescent cells. Continuous dosing is neither necessary nor beneficial — senescent cells accumulate over weeks/months. Monthly pulses target accumulated burden.

Monthly Senolytic Protocol (practical):

• Day 1–2 of each month: Fisetin 500–1000mg (morning) + Quercetin 500mg (morning) + higher fat meal for absorption
• All other days: Daily stack as above
• What to expect: No subjective “feeling” of senolysis. This is a long-term, evidence-light intervention. Track objective markers (see Monitoring Protocol).

⚠️ Do NOT use:

• Dasatinib (prescription cancer drug, not appropriate for self-administration)
• ABT-263 (navitoclax) — causes platelet toxicity; Rx only

Monitoring Protocol

Baseline labs before starting, then every 6 months:

Minimum monitoring (budget-conscious):

• hs-CRP, HbA1c, fasting glucose, lipid panel, ALT/AST — available as standard labs, low cost

Animal Evidence Only — Do NOT Extrapolate

These compounds have compelling mouse data. Human translation has NOT been established or has been explicitly tested and failed.

Safety & Interactions

Resveratrol

• Warfarin / anticoagulants: Resveratrol inhibits CYP2C9 — may increase warfarin effect, raising bleeding risk. Do not combine without INR monitoring.
• Hormonal medications: Weak estrogenic activity; theoretical concern with hormone-sensitive conditions.

NMN / NR

• Cancer concern: NAD+ is required for cancer cell metabolism. Theoretical risk that NAD+ boosting could support tumor growth. Limited human evidence exists on this. Individuals with active cancer or high cancer risk should consult oncologist before NMN/NR.
• Nicotinamide (NAM) at high doses: Inhibits sirtuins — counterproductive. This applies to NAM specifically, less clearly to NMN/NR at standard doses.
• Diabetes medications: NMN showed insulin-sensitizing effects; monitor blood glucose if on metformin or insulin.

NAC (in GlyNAC)

• Bleeding: NAC may mildly inhibit platelet aggregation at high doses. Caution with anticoagulants.
• Acetylcysteine odor: Sulfur smell is normal; not a sign of product degradation.
• Asthma: Inhaled NAC can cause bronchospasm; oral NAC is generally safe.

Fisetin

• Drug interactions: Fisetin inhibits CYP3A4 and CYP2C9 enzymes. Theoretical interaction with any drug metabolized by these pathways (many statins, some antihypertensives, immunosuppressants). Pause senolytics if starting new prescription medications.
• Quercetin + thyroid medication: Quercetin may interfere with levothyroxine absorption. Separate dosing by 4+ hours.
• Immunosuppressants: Senolytics affect immune-senescent cell populations. Caution in transplant recipients.

Taurine

• No significant drug interactions known. Safe at 3g/day based on extensive use in energy drinks and clinical settings.

Spermidine

• No significant drug interactions known at supplement doses. Naturally occurring in many foods.

General Principles

• Always disclose supplement use to your physician, particularly before surgery (stop senolytics 2 weeks pre-op due to possible platelet effects)
• Pregnancy/breastfeeding: None of these supplements have adequate safety data; avoid
• Children and adolescents: Not appropriate targets for longevity supplementation

Limitations & Caveats

This section is intentionally uncomfortable. Read it.

The Longevity Hype Problem

The longevity supplement market is estimated at $25+ billion globally. The incentive to sell unproven products is enormous. Specific dynamics that create hype:

1. Animal data published as human insight: A mouse study shows compound X extends lifespan. Supplement company launches product the next day. The study was in inbred mice with a specific genetic background, started at equivalent of “30 years old,” and given in doses that would require drinking a bathtub of the supplement daily as a human.

2. Biomarker marketing: “Raises NAD+ by 40%!” — This is a blood measurement proxy. It says nothing about whether the raised NAD+ improved any organ function, reduced disease risk, or will extend your life.

3. Correlation sold as causation: People who eat more spermidine-rich foods live longer. But people who eat wheat germ, aged cheese, and legumes also eat Mediterranean-adjacent diets, exercise more, and have higher socioeconomic status. Confounding is nearly impossible to separate.

4. N=1 self-experimentation amplified: Influential longevity advocates (some with financial stakes in supplement companies) publish their personal protocols as if they were clinical trials. This is not science; it is testimony.

What Actually Extends Human Lifespan (Established)

The following interventions have decades of robust epidemiological and RCT evidence for reducing all-cause mortality and extending healthspan:

1. Not smoking — most powerful single intervention
2. Regular aerobic exercise — 150+ min/week moderate intensity; associated with 3–7 year lifespan extension
3. Adequate sleep — 7–9 hours; <6 hours per night associated with significantly elevated all-cause mortality
4. Maintaining healthy body weight — particularly avoiding visceral adiposity
5. Diet quality — Mediterranean, MIND, or similar patterns; not strict caloric restriction for healthy-weight individuals
6. Not drinking alcohol excessively — or at all; no safe alcohol level for cancer risk
7. Social connection and purpose — Blue Zone data; remarkably powerful predictor

Honest comparison: GlyNAC, the best-evidenced supplement in this protocol, showed improvements in functional markers across 16 weeks. Regular resistance exercise shows similar or greater effects across the same biomarkers. Exercise is free. Exercise has no side effects (done safely). Exercise does not require monthly lab work.

The Supplement Stack Is a Layer, Not a Foundation

If you are not sleeping well, not exercising, under chronic stress, or eating poor diet — no supplement stack will meaningfully compensate. The marginal benefit of NMN on top of poor lifestyle is approximately zero. The marginal benefit of GlyNAC on top of an optimized lifestyle is real but modest.

Use this protocol as a top layer on an optimized foundation, not as a substitute for one.

The Bottom Line

Use with confidence (Grade A evidence, low risk):

• GlyNAC (Glycine + NAC): The most evidence-backed longevity supplement combination in this protocol. Multiple RCTs, multiple aging hallmarks addressed, safe, inexpensive. If you only take one thing from this protocol, make it this.

Reasonable additions (Grade B-C, low risk, emerging human evidence):

• NR (or NMN): Raises blood NAD+. Functional benefits are modest in healthy individuals but mechanism is sound. Low risk. Reasonable to add.
• Taurine: Declines with age in humans. Good safety profile. Mechanistic rationale. Await RCT data but low-risk addition now.
• Spermidine: Epidemiological signal + autophagy mechanism. Easily obtained via wheat germ extract or diet. Low cost, low risk.

Proceed with clear eyes (Grade C, intermittent only):

• Fisetin (monthly pulse): Biologically compelling senolytic mechanism. Early human data is promising but not definitive. The “Mayo Protocol” dose (20mg/kg) has not been confirmed as effective in humans. Self-experimenting at 500–1000mg × 2 days/month is low risk; do not expect confirmed benefit.

Do not prioritize (Grade D-E, evidence fails or too weak):

• Resveratrol: Failed in ITP, failed to activate sirtuins in human meta-analysis. Not recommended as longevity agent. At best, an antioxidant with modest cardiovascular benefit.

Do not self-administer:

• Dasatinib: Prescription chemotherapy drug. The D+Q combination requires medical supervision.
• Rapamycin: Prescription immunosuppressant. Despite compelling ITP data, appropriate only under medical supervision with informed risk discussion.

Sources

1. Yoshino M, Yoshino J, Kayser BD, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science. 2021;372(6547):1224–1229. https://doi.org/10.1126/science.abe9985

2. Martens CR, Denman BA, Mazzo MR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018;9(1):1286. https://doi.org/10.1038/s41467-018-03421-7

3. Trammell SAJ, Schmidt MS, Weidemann BJ, et al. Nicotinamide riboside is uniquely and orally bioavailable in healthy humans. Nat Commun. 2016;7:12948. https://doi.org/10.1038/ncomms12948

4. Kumar P, Liu C, Suliburk J, et al. Glycine and N-acetylcysteine (GlyNAC) supplementation in older adults improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, insulin resistance, endothelial dysfunction, genotoxicity, muscle strength, and cognition. Clin Transl Med. 2021;11(3):e372. https://doi.org/10.1002/ctm2.372

5. Kumar P, Osahon OW, Sekhar RV. GlyNAC supplementation improves glutathione deficiency, oxidative stress, mitochondrial dysfunction, inflammation, aging hallmarks, and metabolic health in older humans. J Gerontol A Biol Sci Med Sci. 2023;78(1):75–89. https://doi.org/10.1093/gerona/glac135

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