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Fisetin as a Senolytic Therapy

Evidence Review created on 10/29/2026 using AI4L / Opus 5.5

Also known as: 3,3’,4’,7-tetrahydroxyflavone, 7,3’,4’-trihydroxyflavonol, 5-desoxyquercetin, 5-deoxyquercetin, Cotinin, Fustel, Superfustel, Novusetin, Cognisetin

Motivation

Fisetin is a yellow plant pigment found in small amounts in strawberries, apples, persimmons and onions, and sold in larger doses as a dietary supplement. It draws interest because of a single idea: that it may help the body clear out worn-out cells, which stop dividing with age but linger and release signals that inflame surrounding tissue.

Laboratory and animal studies examined fisetin for this cell-clearing role, and academic medical centers have since begun testing short, high-dose courses in older adults and people with joint disease. Because it is inexpensive and sold without a prescription, many people interested in healthy aging already take it on their own schedules.

This review examines what the human, animal and laboratory evidence shows about fisetin as a cell-clearing therapy for health-focused adults: its possible effects on physical function and inflammation, its risks and drug interactions, the dosing schedules in use, and how the open questions are being tested.

Benefits - Risks - Protocol - Conclusion

This section lists high-level overviews of fisetin as a senolytic (a compound that selectively kills senescent cells, damaged cells that have permanently stopped dividing) from expert platforms and the academic literature.

No directly relevant content was found from Andrew Huberman (the hubermanlab.com site search and a web search returned no fisetin content) or from Chris Kresser (his site has only a broad phytochemical article with a brief descriptive fisetin paragraph and no discussion of senescent-cell clearance).

Grokipedia

  • Fisetin

    Encyclopedic overview of fisetin’s chemistry, food sources, metabolism to geraldol (its main active breakdown product), preclinical senolytic work and Mayo Clinic trials in frailty (age-related loss of strength and reserve).

Examine

No Examine article on fisetin exists as of 10/29/2026; examine.com’s own search returns no results for fisetin and no dedicated supplement page is published.

ConsumerLab

Systematic Reviews

This section lists systematic reviews relevant to fisetin and its drug class; no meta-analysis of fisetin has been published, and no systematic review addresses fisetin’s harms, so the risk side is unrepresented.

Mechanism of Action

Senescent cells are damaged cells that stop dividing yet resist apoptosis (programmed cell death) and release an inflammatory mix of signals, the senescence-associated secretory phenotype (SASP). Senolytics kill these cells by briefly disabling their survival networks, the senescent-cell anti-apoptotic pathways (SCAPs), per a review (Kirkland 2020). Fisetin, a flavonol (a subclass of plant flavonoids), is thought to act on these networks, including PI3K/AKT signaling (an enzyme cascade that keeps cells alive). It triggered apoptosis in senescent human blood-vessel lining cells but not in senescent lung fibroblasts (connective-tissue cells) or fat-cell precursors, showing cell-type specificity (Zhu 2017). Both papers come from the Mayo Clinic group, whose investigators disclose a financial interest in Mayo-held senolytic patents (Hickson 2019).

A review offers a competing view: fisetin’s effects extend beyond senescent-cell killing to antioxidant and anti-inflammatory actions that vary by tissue (Sandoval-Caballero 2026), and a large mouse study saw no fall in p16INK4a (a cell-cycle brake protein marking senescent cells) after dietary fisetin (Harrison 2024).

Key pharmacology:

  • Half-life: about 1.1 hours for plain fisetin and 1.5 hours for a fenugreek-fiber formulation in 15 volunteers (Krishnakumar 2022; by its developer, Akay Natural Ingredients, and Life Extension, a fisetin seller).
  • Metabolism: glucuronidation by UGT enzymes and sulfation by sulfotransferases (both attach water-soluble groups for excretion) (Shia 2009), plus COMT (catechol-O-methyltransferase) methylation to geraldol, an active metabolite.
  • Tissue distribution: in mice, geraldol reached higher tumor levels than fisetin (Touil 2011).
  • Selectivity: low; fisetin also inhibits CYP2C9 (a drug-clearing liver enzyme) (Si 2009).

Historical Context & Evolution

Fisetin was known long before any medical use as a yellow dye in young fustic (smoke tree) wood (Valianou 2009) and as a constituent of the Japanese wax tree (Rhus succedanea), now a commercial source (Hodgin 2021). Its original use was as a colorant, not a therapy.

Pharmacological interest grew from antioxidant, anticancer and nerve-cell research. Salk Institute work found it enhanced long-term memory formation in rodents (Maher 2006), and it later preserved cognition in Alzheimer’s-model mice (Currais 2014).

Its move into health optimization came with the senolytic concept. Mayo Clinic researchers reported in 2017 that fisetin selectively killed senescent blood-vessel lining cells (Zhu 2017), and in 2018 a screen of 10 flavonoids found it the most potent, with late-life feeding extending median and maximum lifespan in a small group of mice (Yousefzadeh 2018). Low cost and supplement status made it the most accessible senolytic, and Mayo launched human trials in frailty and COVID-19 (coronavirus disease 2019).

Two later findings changed the picture without settling it. The National Institute on Aging’s multi-site mouse lifespan program, using about 30 times more mice, found no lifespan effect; its authors suggested the discrepancy may reflect differences in mouse stock or husbandry (Harrison 2024). A placebo-controlled knee osteoarthritis trial posted null clinical results in 2024 (NCT04210986). The mouse-program authors noted that other doses, routes or mouse stocks might behave differently, and larger human trials are still running.

Expected Benefits

High 🟩 🟩 🟩

No benefit reaches High: no human clinical endpoint or validated surrogate has improved with fisetin in trials from more than one independent research group, and the replicated positive findings are animal and cell studies.

Medium 🟩 🟩

No benefit reaches Medium: the only randomized human improvements come from single small trials using daily low doses or add-on designs, which are indirect evidence for intermittent senolytic dosing.

Low 🟩

Lower Insulin Resistance ⭕️ Not Central to Senolytic Therapy

In 22 obese men (11 per arm), 200 mg daily for 12 weeks lowered fasting insulin and HOMA-IR (homeostatic model assessment of insulin resistance, from fasting glucose and insulin) versus placebo (Alipour 2026). This bears on metabolic health, not senescent-cell clearance; daily dosing is indirect for senolytic pulses.

Magnitude: HOMA-IR fell 21.7% within the fisetin-only arm while the placebo arm showed no significant change (its percentage not reported); post-treatment values were significantly lower than placebo, but no between-group difference figure is reported.

Better Neurological Recovery After Clot-Dissolving Stroke Treatment ⭕️ Not Central to Senolytic Therapy

In 192 stroke patients given alteplase (a clot-dissolving drug), adding 100 mg fisetin daily for 7 days improved NIHSS (National Institutes of Health Stroke Scale, a 0–42 deficit score) when treatment began 3–5 hours after onset (Wang 2019). Unreplicated add-on trial; bears on acute stroke care.

Magnitude: NIHSS scores were lower with fisetin than placebo only in the 3–5-hour group (62 patients), not within 3 hours; the paper shows scores graphically and reports no numerical between-group difference.

Physical Function and Joint Symptoms ⚠️ Conflicted

Fisetin improved grip strength and frailty in old mice (Murray 2025). An uncontrolled 40-person study in carpal tunnel syndrome (wrist nerve compression) reported a small symptom-score drop (NCT05416515). A 74-person placebo-controlled knee osteoarthritis trial found no functional, pain or cartilage benefit (NCT04210986). Net: the stronger human evidence is null.

Magnitude: In the knee osteoarthritis trial, six-minute walk distance was 10.5 m shorter with fisetin than placebo, 95% confidence interval (CI, the range likely to contain the true effect) −33.9 to 12.9 m, not significant; knee pain and timed-up-and-go scores did not differ.

Bone Turnover and Bone Density ⚠️ Conflicted

A systematic review of cell and animal studies reports fisetin protecting bone (Yamaura 2022). In the fisetin arm (14 women) of a Mayo Clinic bone trial, five monthly three-day courses neither lowered CTX (C-terminal telopeptide, a bone-breakdown marker) nor changed bone density (NCT04313634). Net: no human bone signal.

Magnitude: Median 20-week change: CTX +13.7% with fisetin vs −7.7% in untreated controls; lumbar spine density 0% vs +0.5%; not compared between groups.

Course of Acute Viral Infection in Older Adults ⚠️ Conflicted

Fisetin cut coronavirus-related deaths in old mice (Camell 2021). Placebo-controlled pilots in COVID-19 outpatients (NCT04771611) and nursing-home residents, the latter stopped for futility (NCT04537299), showed no clear benefit. Net: the mouse signal has not translated.

Magnitude: At 60 days, 26 of 27 fisetin and 22 of 24 placebo outpatients were free of activity limitation on the World Health Organization severity scale; not compared between groups.

Speculative 🟨

Lower Systemic Inflammation Markers ⚠️ Conflicted

Daily fisetin lowered interleukin-8 in colorectal cancer (Farsad-Naeimi 2018) and interleukin-6 in obese men (Alipour 2026); two-day pulses left C-reactive protein (a liver-made inflammation marker) unchanged (NCT04210986). Net: unvalidated markers; no signal at senolytic doses.

Clearance of Senescent Cells ⚠️ Conflicted

Most potent of 10 flavonoids in cultured cells; lowered senescence markers in old mice and human fat explants (Yousefzadeh 2018), but not in diverse mice (Harrison 2024) or human plasma (NCT04313634). Net: animal-only, inconsistent.

Longer Lifespan and Healthspan ⚠️ Conflicted

Late-life fisetin extended median and maximum lifespan in a small mouse study (Yousefzadeh 2018); a 30-times-larger study found no effect in either sex (Harrison 2024). Net: animal-only and unreplicated.

Better Arterial Function

Intermittent fisetin improved blood-vessel lining function and lowered arterial stiffness in old mice by removing senescent cells (Mahoney 2024). Basis is animal work only.

Slower Brain Aging and Memory Loss

Fisetin preserved memory in Alzheimer’s-model (Currais 2014) and rapidly aging mice (Currais 2018). No controlled human cognitive data exist; basis is animal work only.

Benefit-Modifying Factors

  • Genetic polymorphisms: No fisetin pharmacogenetic study exists. Because fisetin is cleared by glucuronidation and methylation, variants in UGT1A1 (a liver enzyme attaching glucuronic acid) or COMT (catechol-O-methyltransferase, which methylates catechol compounds) could plausibly change exposure; this is inferred and untested.
  • Baseline senescent-cell burden: In a dasatinib-plus-quercetin bone trial, benefits concentrated in women with the highest T-cell p16INK4a levels (Farr 2024); whether fisetin follows this pattern is untested.
  • Baseline inflammation and insulin resistance: Positive human signals come from inflamed or insulin-resistant groups, such as colorectal cancer and obesity (Farsad-Naeimi 2018, Alipour 2026); people with low baseline values have less room to change.
  • Sex: Monthly fisetin improved metabolism and cognition in male mice but had no effect in females (Fang 2023); human trials have not reported sex-specific results.
  • Pre-existing conditions: Knee osteoarthritis showed no benefit (NCT04210986), whereas obesity showed metabolic improvement with daily dosing (Alipour 2026); benefit may depend on how senescence-driven a condition is.
  • Age: Senescent cells accumulate with age, so older adults have the greatest theoretical benefit; fisetin helped old but not young mice (Murray 2025), and human trials mostly enroll adults over 60.

Potential Risks & Side Effects

High 🟥 🟥 🟥

No risk reaches High: no adverse event has occurred more often with fisetin than with placebo in controlled trials from more than one independent research group.

Medium 🟥 🟥

No risk reaches Medium: the only controlled excess-harm signal comes from a 14-person open-label arm and is outweighed by a larger double-blind placebo-controlled trial.

Low 🟥

Gastrointestinal and General Adverse Events at High Intermittent Doses ⚠️ Conflicted

In a Mayo bone trial, 2 of 14 women withdrew for adverse events and 1 had serious gastric bleeding; controls had none (NCT04313634). A double-blind trial found no excess (NCT04210986); bloating appears in a pharmacokinetic (absorption and clearance) study’s full text, not its abstract (Krishnakumar 2022). Net: no placebo-controlled excess.

Magnitude: Any treatment-emergent adverse event: 28 of 34 with fisetin vs 33 of 40 with placebo; odds ratio (OR, the relative odds of an event) 0.99 (95% CI 0.25–4.02); nausea 4 of 34 vs 5 of 40.

Speculative 🟨

Chromosome Damage

In cultured human cells, fisetin inhibited topoisomerase II (an enzyme untangling DNA, the genetic material), causing chromosome loss at low and breaks at high concentrations (Olaharski 2005). Basis is laboratory-dish (in vitro) work only.

Impaired Tissue Repair After Injury or Surgery

Senescent cells aid wound closure in mice by secreting a repair growth factor (Demaria 2014). Clearing them around surgery could slow healing; basis is mechanistic, with no fisetin data.

Raised Levels of Co-Prescribed Drugs

Fisetin competitively inhibited CYP2C9 in vitro (Si 2009), which could raise levels of warfarin or other narrow-margin drugs. Basis is in-vitro; no human interaction study exists.

Risk-Modifying Factors

  • Genetic polymorphisms: Carriers of CYP2C9*2 or *3 (reduced-function variants of the warfarin-clearing enzyme) already show heightened warfarin sensitivity; added CYP2C9 inhibition by fisetin (Si 2009) could compound this. Reduced UGT1A1 activity (Gilbert syndrome) may slow fisetin clearance; both are inferred.
  • Baseline biomarkers: Raised liver enzymes, impaired kidney function or a high INR (international normalized ratio, a clotting-time measure) narrow the safety margin; the Mayo bone-trial protocol stopped dosing if liver values exceeded twice the upper normal limit (NCT04313634).
  • Sex: No sex-specific harm data exist; the trial with excess withdrawals enrolled only women (NCT04313634), so sex and dose effects cannot be separated.
  • Pre-existing conditions: Active cancer treatment, recent surgery or open wounds, pregnancy and liver disease raise theoretical risks through topoisomerase inhibition, impaired repair and slower clearance; none has human data.
  • Age: Older adults take more interacting medications, and weight-based dosing means 12–20 capsules of 100 mg per day; frail nursing-home residents were dosed in a small pilot stopped for futility (NCT04537299).

Key Interactions & Contraindications

Documented interactions:

  • Fenugreek-fiber hydrogel formulation (FF-20): raised fisetin exposure 26.9-fold over plain fisetin in 15 volunteers (Krishnakumar 2022); consequence: equal milligram labels give very different blood levels. Mitigation: dose by formulation, not label weight.
  • Interval resistance-aerobic training: no blunting found; in obese men, training plus 200 mg daily gave the largest within-group insulin-resistance and interleukin-6 reductions, without a reported comparison against training alone (Alipour 2026).

Theoretical interactions (inferred from mechanism, not studied in humans):

  • CYP2C9-cleared prescription drugs (warfarin, phenytoin, glipizide): inferred from competitive CYP2C9 inhibition in vitro (Si 2009); consequence: higher drug levels, bleeding with warfarin, low blood sugar with glipizide. Mitigation: INR check within a week of a pulse.
  • Over-the-counter NSAIDs (nonsteroidal anti-inflammatory drugs: ibuprofen, diclofenac, naproxen): inferred from CYP2C9 inhibition measured with diclofenac as the test drug (Si 2009); consequence: higher exposure and stomach bleeding risk. Mitigation: avoid on dosing days.
  • CYP2C8 (a drug-clearing liver enzyme) and liver-uptake-transporter substrates (repaglinide, cyclosporine, tacrolimus, bosentan): inferred from selective CYP2C8 inhibition by fisetin in human liver cell fractions (Shrestha 2018); trial protocols hold them around dosing (NCT04210986); consequence: toxic drug levels. Mitigation: prescriber-supervised hold.
  • Anticoagulant and antiplatelet drugs (clot-preventing medicines: apixaban, clopidogrel, aspirin): inferred from possible additive flavonol effects on platelets; Mayo protocols hold antiplatelets during dosing (NCT04313634); consequence: increased bleeding risk. Mitigation: prescriber-supervised hold.
  • Glucose-lowering drugs (metformin, insulin, glipizide): inferred from fisetin’s insulin and glucose lowering in obese men (Alipour 2026); consequence: low blood sugar. Mitigation: glucose checks on dosing days.
  • Topoisomerase-targeting chemotherapy (doxorubicin, etoposide): inferred from fisetin’s topoisomerase II inhibition (Olaharski 2005); consequence: altered tumor response or added DNA damage. Mitigation: use only under oncology supervision.
  • Other flavonoid supplements (quercetin, luteolin, apigenin): all inhibit CYP2C9 in vitro (Si 2009); consequence: compounded enzyme inhibition with the drugs above. Mitigation: avoid combining them with fisetin on dosing days.
  • Glucose-lowering supplements (berberine): inferred from additive glucose lowering; consequence: low blood sugar, especially with diabetes drugs. Mitigation: glucose checks.

Populations who should avoid Fisetin:

  • Pregnancy and breastfeeding: inferred from topoisomerase II inhibition and chromosome-loss effects in cultured cells (Olaharski 2005); no human data.
  • People with unhealed wounds or planned surgery: inferred from the wound-repair role of senescent cells in mice (Demaria 2014); no human data.
  • People receiving chemotherapy outside a trial: inferred from topoisomerase II inhibition (Olaharski 2005); no human data.
  • People on warfarin with unstable INR: inferred from CYP2C9 inhibition (Si 2009); no human data.
  • People with significant liver disease: inferred from rapid, extensive sulfation and glucuronidation of fisetin in rats (Shia 2009), clearance steps that liver disease may slow; no human data.

Risk Mitigation Strategies

Doses and timings below follow common practice unless cited.

  • Single test pulse first: one day of the planned dose before a full two- or three-day course screens for nausea or other stomach upset, the most reported complaints at high doses.
  • Meals and split capsules: spreading 12–20 capsules across breakfast and lunch limits stomach upset, the main tolerability risk; food may also aid absorption (ConsumerLab fisetin answer).
  • Liver stopping rule: liver enzymes checked before and 1–2 weeks after the first pulse, with dosing stopped above twice the upper normal limit, the Mayo bone-trial rule (NCT04313634), detect slowed liver clearance that would raise co-prescribed drug levels.
  • Drug-interaction hold: an INR check 3–7 days after a pulse for warfarin users, no NSAIDs on dosing days, and prescriber-agreed holds of narrow-margin CYP2C8/CYP2C9 drugs reduce bleeding and toxicity risk.
  • Surgery and wound pause: no pulses from at least 2 weeks before elective surgery until wounds heal, avoiding interference with senescent-cell-assisted repair.
  • Glucose checks with diabetes drugs: glucose readings on dosing days and the day after detect low blood sugar early.
  • Dose by formulation: the trial dose of 20 mg/kg/day (NCT04210986) used plain fisetin; enhanced-absorption products deliver far higher blood levels (Krishnakumar 2022), so applying it to them risks overexposure.

Therapeutic Protocol

Timing, cycling and titration steps without a citation reflect common practice.

  • Mayo two-day pulse: about 20 mg/kg/day orally on 2 consecutive days, monthly for 2 months (NCT03430037); the “hit-and-run” approach popularized by the Mayo Clinic Kirkland–Tchkonia group in a review (Kirkland 2020).
  • Mayo three-day monthly course: about 20 mg/kg/day for 3 consecutive days every 28 days, five courses over 20 weeks, as used in older women (NCT04313634).
  • Low-dose intermittent alternative: 2 mg/kg/day for 3 days every 2 weeks, six courses, in a University of Colorado vascular trial (NCT07871162); one-tenth the Mayo dose.
  • Daily low-dose approach: 100 mg/day (Farsad-Naeimi 2018) or 200 mg/day (Alipour 2026); acts as an anti-inflammatory rather than a tested senolytic regimen.
  • Weekly high-dose approach: Life Extension describes once-weekly high doses of fisetin with other plant compounds, without trial support (Life Extension, Senolytics Remove Aged Cells); Life Extension sells these products.
  • Time of day: no study compares timing; morning or midday with a fat-containing meal is common, keeping evening free if stomach upset occurs.
  • Half-life: about 1.1–1.5 hours (Krishnakumar 2022); pulses rely on brief exposure killing senescent cells, which take weeks to re-accumulate, per a review (Kirkland 2020).
  • Single or split dose: trials specify a daily total; splitting 12–20 capsules across two meals improves tolerance without evidence of lost effect.
  • Genetic polymorphisms: no pharmacogenetic dosing data exist; CYP2C9 reduced-function carriers taking warfarin are the group in which extra INR monitoring is most relevant.
  • Sex: no sex-specific human dosing; mouse benefits appeared in males only (Fang 2023).
  • Age: trials enroll mostly adults over 60 or 70 at full weight-based doses; a single-day test pulse is a common first step in frail older adults.
  • Baseline biomarkers: high senescent-cell burden predicted response to another senolytic (Farr 2024); no fisetin-specific selection marker is validated.
  • Pre-existing conditions: obesity and insulin resistance showed responses to daily dosing (Alipour 2026); knee osteoarthritis did not respond to pulses (NCT04210986).

Discontinuation & Cycling

  • Short-term by design: senolytic regimens are brief pulses, not continuous therapy; the longest tested schedule is five monthly courses over 20 weeks (NCT04313634), and lifelong repetition is untested.
  • Withdrawal effects: none reported in completed trials; senescent cells re-accumulate over weeks, so effects, if any, are expected to fade gradually.
  • Tapering: not applicable; pulses end abruptly by protocol, and daily low-dose users can stop without tapering.
  • Cycling for efficacy: intermittent cycling is the mechanism itself, giving time for senescent cells to re-accumulate between pulses, per a review (Kirkland 2020); optimal intervals of monthly, quarterly or longer are unknown.

Sourcing and Quality

  • Regulatory status and purity: fisetin is sold as a dietary supplement, which the FDA (Food and Drug Administration) does not approve before marketing (FDA Q&A on dietary supplements), so identity and dose rest on the manufacturer.
  • Source material: most fisetin is extracted from the Japanese wax tree (Rhus succedanea); branded ingredients such as Novusetin are standardized extracts used in several trials (Wang 2019, NCT06796374).
  • Formulation: the fenugreek-fiber hydrogel form delivered far more fisetin per milligram than plain powder in humans (Krishnakumar 2022); other enhanced forms lack comparable human data, and trial doses of 20 mg/kg used plain fisetin.
  • What to look for: a certificate of analysis showing high-performance liquid chromatography purity of at least 98%, heavy-metal and microbial testing, and lot numbers; independent seals (United States Pharmacopeia, NSF International) are rare for fisetin.
  • Stability: fisetin content in mouse-feed batches averaged 99% of target (standard error, a measure of how precisely that average is known, 9%; five batches) in a large study (Harrison 2024); sealed, cool, dark storage and in-date products reduce degradation.

Practical Considerations

  • Time to effect: unknown in humans; senescent-cell clearance in mice was detectable within weeks (Yousefzadeh 2018), and trials assess function from 2 weeks to 12 months after pulses.
  • Common pitfalls: assuming mouse lifespan results apply to people, expecting senolysis from 100 mg daily capsules, ignoring formulation strength, and combining pulses with warfarin, NSAIDs or other flavonoids without monitoring.
  • Regulatory status: sold in the US as a dietary supplement, a category the FDA does not approve before marketing (FDA Q&A on dietary supplements); use as a senolytic therapy is therefore off-label in practice and investigational in trials.
  • Cost and capsule burden: not exceptionally expensive, but a 20 mg/kg pulse for an 80 kg adult means 16 capsules of 100 mg per day.
  • Funding gap: as an unpatentable supplement, fisetin has no sponsor with an incentive to fund large outcome trials, and insurers have no reason to pay for them; this structurally limits the evidence base.

Interaction with Foundational Habits

  • Sleep: None known. No sleep disruption appears in completed trials’ adverse-event lists; a trial pairing fisetin with urolithin A is measuring sleep and aging markers (NCT06990256). Practical: dosing time relative to sleep is unconstrained.
  • Nutrition: Indirect. Food supplies only trace amounts; about a pound of strawberries equals a typical capsule (ConsumerLab fisetin answer). Taking it with a fat-containing meal may aid absorption; a food-effect study is underway (NCT06796374).
  • Exercise: Possibly potentiating, not blunting. In obese men, 200 mg daily plus interval resistance-aerobic training produced the largest within-group insulin-resistance and interleukin-6 reductions, without a reported comparison against training alone (Alipour 2026). A systematic review found exercise itself lowers senescence markers in humans (Chen 2021).
  • Stress management: None known. No human study links fisetin to cortisol or stress responses; mechanism is unstudied, so no timing or technique adjustments apply.

Monitoring Protocol & Defining Success

Baseline testing before the first pulse sets a personal reference point: liver enzymes, kidney function, fasting glucose and insulin, an inflammation panel, and INR for anyone taking warfarin. Function tests recorded at the same visit, such as six-minute walk distance, grip strength and chair-rise time, give a non-laboratory baseline for frailty-related goals.

Ongoing monitoring follows this cadence: safety labs 1–2 weeks after the first pulse, then every 3–6 months while cycling; inflammation and metabolic markers at 3 and 6 months; INR 3–7 days after each pulse for warfarin users. Success means stable safety labs plus a sustained improvement in function or inflammation over the personal baseline; no blood marker can yet confirm that senescent cells were cleared.

Biomarker Optimal Functional Range Why Measure It? Context/Notes
Interleukin-6 No established target; track change from own baseline Expected to change: inflammation signal Fell with daily 200 mg in obese men (Alipour 2026); assay availability varies; morning draw for consistency
Fasting glucose 70–99 mg/dL (standard reference range) Safety check with glucose-lowering drugs; may change 8–12 hour fast; pair with fasting insulin; check on dosing days if on diabetes drugs
HOMA-IR No established target; track change from own baseline Expected to change: insulin resistance Homeostatic model assessment of insulin resistance, calculated from fasting glucose and insulin; fell with daily dosing (Alipour 2026)
ALT 7–55 U/L (standard reference range) Safety check: stop if above twice the upper normal limit Alanine aminotransferase, a liver enzyme; stopping rule from the Mayo bone-trial protocol (NCT04313634); pair with AST (aspartate aminotransferase)
Creatinine 0.74–1.35 mg/dL men, 0.59–1.04 mg/dL women (standard reference range) Safety check: kidney clearance Used to estimate eGFR (estimated glomerular filtration rate, kidney filtering capacity); trials excluded significant kidney disease
INR No established target; track against the prescriber-set warfarin range Safety check: CYP2C9 inhibition may raise warfarin effect International normalized ratio, a clotting-time measure; only for warfarin users; check 3–7 days after a pulse
T-cell p16INK4a No established target; research assay only, so track change from own baseline where offered in a trial Expected to change: senescent-cell burden Proposed trial-selection marker (Farr 2025); not commercially standardized

Qualitative markers:

  • Walking endurance and ease on stairs
  • Joint pain and morning stiffness
  • Energy and fatigue in the weeks after a pulse
  • Stomach tolerance on dosing days
  • Wound and minor-injury healing speed
  • Sleep quality

Emerging Research

  • Older adults’ frailty and inflammation (AFFIRM-LITE): phase 2 (mid-stage efficacy) placebo-controlled trial in 40 older adults, primary outcome blood inflammation markers (NCT03675724). Positive: first controlled human senolytic signal for fisetin. Null: weakens inflammation-based rationale for pulses.
  • Older women’s walking function (AFFIRM): phase 2 placebo-controlled trial in 40 older women, primary outcome six-minute walk (NCT03430037). Positive: moves physical function toward Medium. Null: adds to the knee osteoarthritis null.
  • Breast cancer survivors (TROFFi): phase 2 placebo-controlled trial in 88 survivors, primary outcome six-minute walk (NCT05595499; design in Ji 2026). Positive: supports fisetin against treatment-induced aging. Null: limits use after chemotherapy.
  • Breast cancer survivors with exercise (PROFFi): triple-blind placebo-controlled phase 2 trial in 164 survivors, fisetin 3 days every 2 weeks with or without supervised exercise, primary outcome six-minute walk (NCT06113016). Positive: supports pulses and tests exercise synergy. Null: weakens the physical-function rationale.
  • Sepsis (life-threatening infection response) organ failure (STOP-Sepsis): phase 2 trial of one or two 20 mg/kg doses versus placebo in 220 patients, primary outcome organ-failure score (NCT05758246). Positive: first acute clinical benefit. Null: further weakens the infection item.
  • Vascular function in older adults: phase 1/2 placebo-controlled trial in 70 adults, primary outcome endothelial (blood-vessel lining) function at 1 month; primary completion passed in March 2026, final completion due March 2027, no results posted (NCT06133634). Positive: first human arterial evidence. Null: arterial item stays Speculative.
  • Low-dose daily fisetin and chronic inflammation: triple-blind trial of 100 mg daily versus placebo for 7 weeks in 120 adults over 50, primary outcome suPAR (soluble urokinase plasminogen activator receptor, a chronic-inflammation marker) (NCT07195318; protocol in Tavenier 2026). Positive: supports daily dosing. Null: favors pulses or neither.
  • Age and food effects on absorption: pharmacokinetic study of 500 mg in 80 young and old adults, fasted versus fed (NCT06796374). Positive age or food effect: refines dosing. Null: simplifies dosing.
  • Hospitalized COVID-19 (COVID-FISETIN): phase 2 trial of 80 participants; registered completion September 2026 passed, status active, not recruiting, no results posted (NCT04476953).
  • Better senescence biomarkers: T-cell p16 and plasma secretory panels may identify responders (Farr 2025); this could rescue fisetin in high-burden subgroups or confirm broad inactivity.
  • Epigenetic clocks as endpoints: senescence-trained DNA methylation clocks (patterns of chemical tags on DNA, the genetic material) did not fall after senolytic treatment (Kasamoto 2026), weakening clock-based claims of rejuvenation.

Conclusion

Fisetin is an inexpensive plant pigment sold as a supplement and promoted as a way to clear worn-out cells that build up with age and inflame nearby tissue. For health-focused adults weighing it, the evidence splits sharply by species. In laboratory dishes and in mice, fisetin removed such cells and improved blood vessels, muscle, memory and in one study lifespan, although a much larger mouse study found no lifespan gain.

In people, the record is thin and mostly null for the cell-clearing use. Short high-dose courses did not improve joint function, bone strength or the course of viral infection in early controlled studies, and no study has yet shown that fisetin clears worn-out cells in humans. Small studies of lower daily doses suggest modest drops in inflammation and better blood-sugar control, but these used a different schedule and are unconfirmed.

Short courses appear mostly well tolerated, with stomach upset the most reported complaint and a single serious stomach bleed in one small study. The main open concerns are effects on other medicines, especially clot-preventing and diabetes drugs, possible slower wound healing, and unknown effects of repeated courses over years.

The evidence base is small and early, and much of it comes from groups with a stake in the outcome: researchers whose institution holds patents on cell-clearing treatments, and supplement companies that sell fisetin products. Several larger controlled studies are now underway, and the case for fisetin in this role remains uncertain.

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