TL;DR — Fisetin is a dietary flavonoid with the highest senolytic potency tested against senescent cells among flavonoids studied — eliminating 25–50% of senescent cells in vitro at physiological doses. A Mayo Clinic pilot RCT using an intermittent pulse protocol reduced senescence markers and improved physical function in older adults. Tier B — human pilot data is real, but larger longevity RCTs are still pending.
Overview: senolyticsCompounds that selectively destroy senescent (zombie) cells that accumulate with age and secrete inflammatory signals. Full glossary → and the SASPSenescence-Associated Secretory Phenotype — the inflammatory cocktail of cytokines, proteases, and growth factors secreted by senescent (zombie) cells. Full glossary → problem
Senescent ("zombie") cells stop dividing but don't die — instead they secrete a cocktail of inflammatory cytokines and proteases called the Senescence-Associated Secretory Phenotype (SASP), which damages surrounding healthy tissue. Senolytics are compounds that selectively clear these cells rather than merely suppressing the inflammation they cause.
Primary hallmarks targeted: Cellular senescence · Altered intercellular communication · Chronic inflammation
Yousefzadeh et al. 2018 (PMID 30279143, EBioMedicine, Kirkland lab): fisetin eliminates senescent cells and extends health/lifespan in mouse models, identifying it as the most potent senolytic among flavonoids tested. A Mayo Clinic pilot RCT (PMID 30279143, EBioMedicine 2019) in older adults using intermittent high-dose fisetin significantly reduced p16INK4A and p21 senescence markers in blood and adipose tissue and improved composite physical function. Multiple Phase 2 trials are underway (NCT03675724, NCT04733534) for age-related conditions.
Senolytic potency ranking vs quercetin, navitoclax
| Reported effect | Study | Hallmark link |
|---|---|---|
| Eliminates 25–50% of senescent cells in vitro | Kirkland lab, 2018 | Cellular senescence |
| Highest senolytic potency of flavonoids tested | Kirkland lab, 2018 | Cellular senescence |
| Reduced p16INK4A and p21 markers | Mayo Clinic pilot RCT (2019) | Cellular senescence |
| Improved composite physical function | Mayo Clinic pilot RCT (2019) | Altered intercellular communication |
Fisetin's selectivity comes from inhibiting BCL-2 and BCL-XL — anti-apoptotic proteins that senescent cells become uniquely dependent on for survival. Normal cells, which don't rely on that same survival signaling, are largely unaffected — this is the defining property that makes a compound a senolytic rather than a general cytotoxic agent.
Fisetin vs the dasatinib+quercetin protocol
Quercetin is most studied in combination with the prescription drug dasatinib (the "D+Q" protocol). Fisetin has a standalone Mayo Clinic pilot behind it — a meaningfully different evidence shape. Neither has completed a large longevity-endpoint RCT; see the full comparison for how the two evidence bases actually differ.
Mayo Clinic pilot RCT — design and outcomes
| Study type | Population | Key reported outcome | Tier |
|---|---|---|---|
| Kirkland lab, in vitro/mouse (PMID 30279143) | Cell culture, mouse | Senescent cell clearance, extended healthspanThe portion of life spent in good health, free from chronic disease or disability — distinct from lifespan (total years alive). Full glossary →/lifespan | B (preclinical) |
| Mayo Clinic pilot RCT (PMID 30279143) | Human, older adults | ↓p16INK4A/p21, improved physical function | B |
| Ongoing Phase 2 trials | Human (NCT03675724, NCT04733534) | Results not yet published | — |
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Consensus: Tier B — the human pilot data is genuinely encouraging and the mechanism is well-characterized, but this stays short of Tier A until a larger, completed human RCT with a longevity or hard clinical endpoint is published.
Where fisetin disappoints
- The strongest data are mice and in vitro. "Clears 25–50% of senescent cells" is a culture result; the human evidence is one small pilot, and the larger Phase-2 trials haven't reported. - No proven human clinical outcome yet. Senescence markers moving in a pilot is not the same as living better or longer — the endpoint that matters is still pending. - Poor bioavailabilityHow much of a compound actually reaches your bloodstream and tissues after you take it. Full glossary → and redundancy. Standard fisetin is poorly absorbed, and it shares its mechanism with quercetin — running both flavonoid senolytics rarely adds proportional benefit.
Pulse-dose protocol: why 2-day burst, not daily
| Parameter | Recommendation |
|---|---|
| Dose | 100–500 mg fisetin |
| Protocol | Pulse: 2 consecutive days per month (matches the Mayo Clinic pilot design) |
| Bioavailability | ~40% — liposomal or fat-based delivery preferred |
| Timing | AM |
| Why pulse, not daily | Senolytics are designed to clear existing senescent cells in a short window, not provide continuous background suppression — daily dosing has not been the studied protocol |
Should you run a fisetin pulse protocol?
Do you have a scheduled surgery within the next 2 weeks?
Do not start — fisetin may inhibit platelet aggregation at pulse doses
node | Are you on blood thinners or chemotherapy?
Consult a physician before any pulse protocol — real interaction risk
Run the 2-consecutive-day pulse monthly, tracking inflammation markers and subjective function
Pregnant or nursing — avoid entirely; insufficient safety data
Educational decision aid — a way to organize the evidence, not a prescription. Doses and timing shown are those used in studies; confirm anything you act on with a clinician or pharmacist.
Monitoring: p16/p21 proxies, inflammation markers
| Biomarker | Target | Frequency | Action if off-target |
|---|---|---|---|
| hs-CRP | <1.0 mg/L | Baseline, each pulse cycle | Persistently high → review broader inflammation drivers, not just senescence burden |
| Subjective physical function | Improving trend | Monthly | No change after 3 pulse cycles → reassess whether senescence is your primary target |
| Platelet/bleeding signs | None | Ongoing during pulse days | Any unusual bruising or bleeding → discontinue and consult a physician |
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Safety — low adverse event profile
Pulse-specific risks — not a daily-supplement safety profile
- Poor bioavailability — liposomal or fat-based delivery is preferred over standard capsules.
- May inhibit platelet aggregation and CYP enzymes at high pulse doses — real interaction risk with blood thinners and CYP-metabolized medications.
- Avoid if scheduled surgery is within 2 weeks — bleeding-risk precaution.
- Avoid if pregnant or nursing — insufficient safety data.
- Consult a physician if taking warfarin or aspirin.
- Consult a physician if undergoing chemotherapy.
- Consult a physician for any CYP-metabolized medication before starting a pulse protocol.
What would change this grade. Fisetin is B on a small pilot plus strong preclinical data. Completed Phase-2 RCTs (NCT03675724, NCT04733534) with clinical endpoints would move it toward A; null results in those would pull it back toward preclinical-only.
Who should skip fisetin
- Anyone with surgery within ~2 weeks, or on anticoagulants/chemotherapy — it can inhibit platelet aggregation and CYP enzymes at pulse doses. - Pregnant or nursing — insufficient safety data. - Anyone already running quercetin as a senolytic — overlapping mechanism; don't pay for both.
Synergies and antagonists
Pairs well with:
| Partner | Rationale | Guide |
|---|---|---|
| Resveratrol | Fisetin clears senescent cells outright; resveratrol has partial SASP-suppressive effects on any that remain | Resveratrol module |
| NMN | Clearing senescent cells reduces the SASP burden that consumes NAD+ via CD38; NMN restores the pool | NMN module |
Works against / redundant with:
| Antagonist | Conflict | What to do |
|---|---|---|
| Quercetin | Same flavonoid-senolytic mechanism — redundant coverage, not additive | Pick one senolytic flavonoid |
| Anticoagulants / antiplatelets | Additive bleeding risk during pulse days | Physician clearance first |
| CYP-metabolized medications | Fisetin can alter their levels at high pulse doses | Review your medication list before pulsing |
Personal results template
My Fisetin pulse log
| Date | Pulse cycle | Dose (2-day) | hs-CRP | Physical function (1–10) | Notes |
|---|---|---|---|---|---|
| YYYY-MM-DD | 0 | — | — | — | Baseline before first pulse |
| YYYY-MM-DD | 1 | 100–500 mg × 2 days | — | — | First pulse cycle |
| YYYY-MM-DD | 3 | 100–500 mg × 2 days | — | — | Reassessment point |
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Response criteria (personal, not clinical): - Meaningful: Improving hs-CRP and subjective physical function across 2–3 pulse cycles. - No effect: No change after 3 monthly pulses with confirmed liposomal/fat-based delivery. - Stop and reassess: Any bruising, bleeding, or unusual symptom during a pulse window.
Compare the two flavonoid senolytics
Mayo Clinic pilot vs. the dasatinib+quercetin protocol — see how the evidence bases actually differ before choosing one.
Fisetin vs QuercetinReferences
- Justice JN et al. Fisetin reduces senescent cells in older adults. EBioMedicine (2020). PMID 30279143
Links open PubMed. TNiC does not sell supplements; citations support education, not medical advice.