Senolytics (Fisetin)

Mayo Clinic trials ongoing. Accessible natural alternative to pharmaceutical senolytics. Strong preclinical data. Human evidence emerging. UPDATE (August 2026): Context that should temper enthusiasm. A peer-reviewed systematic review of human nutritional interventions and cellular senescence (Ageing Research Reviews 2026; 27 trials, 3,811 participants) found that dietary and nutraceutical interventions consistently move SASP-associated circulating inflammatory markers but leave classical markers of senescent-cell abundance - CDKN2A/p16, CDKN1A/p21 - and telomere length largely unchanged or highly variable. Evidence specifically for dietary supplements was described as limited and heterogeneous. Fisetin's senolytic case therefore still rests principally on preclinical data; no human trial has demonstrated that fisetin reduces senescent-cell burden in people. Mayo Clinic trials remain ongoing and are the ones to watch. UPDATE (August 23, 2026): CHALLENGED — a methodological problem affecting the senescence literature that fisetin's case partly rests on. A research-integrity investigation reported in Nature News (21 August 2026) identified at least 54 cell-aging papers whose methods list an antibody raised against Escherichia coli beta-galactosidase, apparently used to detect beta-galactosidase in mammalian cells as a senescence marker; cross-kingdom reactivity is not supported by theoretical or experimental evidence. Journals including Cell and Springer Nature have said they are assessing. This is journalism reporting a post-publication audit rather than a peer-reviewed re-analysis, and it does not establish that any particular conclusion is wrong. Its relevance here is narrower and practical: SA-beta-gal staining is the assay most often invoked in consumer senolytic marketing, and it now has a validation question layered on top of the pre-existing dispute over whether it identifies senescent cells reliably at all. Combined with the 2026 systematic review finding that nutritional interventions move SASP markers but not senescent-cell abundance markers, the evidentiary basis for claiming that fisetin clears senescent cells in humans remains absent. UPDATE (September 6, 2026): Fisetin finally has a properly controlled human trial - but note carefully what it is and is not. A peer-reviewed PROTOCOL (Basic & Clinical Pharmacology & Toxicology 2026;139(3):e70290; Tavenier, Rasmussen et al., Copenhagen University Hospital Amager and Hvidovre) describes a triple-blind, randomised, placebo-controlled trial randomising generally healthy adults aged 50+ to 100 mg oral fisetin or placebo ONCE DAILY for 7 weeks. The primary outcome is the between-group change in plasma soluble urokinase plasminogen activator receptor (suPAR); the secondary outcome is occurrence and severity of adverse events; exploratory outcomes include other inflammation, aging and cellular-senescence biomarkers plus frailty, physical and cognitive function. NO RESULTS HAVE BEEN REPORTED. Two design choices are informative in themselves: the regimen is low-dose and continuous rather than the high intermittent pulses used in most senolytic protocols, and the primary endpoint is an inflammatory/mortality-associated biomarker rather than senescent-cell burden - an implicit acknowledgement that senescent-cell quantification in humans remains unreliable. Separately, a peer-reviewed multitissue single-cell study of dasatinib + quercetin in aged mice (Nature Aging, June 2026) found that early-initiated, prolonged dosing outperformed short late-stage courses, with incomplete senescent-cell clearance throughout; that study used D+Q rather than fisetin, so the extrapolation to fisetin cycling is indirect. As of this update, no human trial has demonstrated that fisetin reduces senescent-cell burden or improves any clinical outcome.

Evidence Scale