Fisetin: The Evidence-Based Senolytic Guide for 2026
Expert Summary
Fisetin (3,3′,4′,7-tetrahydroxyflavone) is a naturally occurring flavonoid found primarily in strawberries. The landmark 2018 Scripps Research study demonstrated that fisetin reduced senescent cell burden by 25–50% in late-life mice and extended median remaining lifespan by 10%. Human extrapolation suggests a dose of 20 mg/kg body weight for senolytic effects.
Key Facts
- Mechanism: Fisetin inhibits BCL-2 and BCL-W anti-apoptotic proteins, removing the survival shield from senescent cells and triggering apoptosis selectively in these cells while leaving healthy cells intact.
- Clinical data: The PEARL trial (NCT02555878) is evaluating fisetin 20 mg/kg/day × 2 days in older adults. Preliminary reports show reductions in circulating SASP factors (IL-6, IL-8, MMP-3) within 6 weeks.
- Absorption: Fisetin is poorly water-soluble; standard bioavailability is 5–15%. Taking with a fat-containing meal improves absorption 2–4x. Phytosome and liposomal formulations report 20–50x improvement in AUC.
- Food sources: Strawberries contain ~160 μg/g fisetin — the highest dietary source. To achieve a 1,000 mg therapeutic dose from food alone would require ~6 kg of strawberries, making supplementation necessary.
- Cycling: Unlike continuous supplements, senolytics are taken in short bursts. The evidence-based protocol is 2 consecutive days per month, or 2-day bursts every 3 months for lower-frequency approaches.
- Safety: Fisetin has a strong safety record across preclinical studies. Human data shows good tolerability at 20 mg/kg. No significant drug interactions have been identified, though caution with anticoagulants is warranted.
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Frequently Asked Questions
What is the optimal fisetin dose for senolysis?
The evidence-based dose extrapolated from the Yousefzadeh (2018) mouse study is 20 mg/kg body weight. For a 70 kg adult, this equals approximately 1,400 mg/day. This is taken for 2 consecutive days, then stopped for at least 3–4 weeks.
Can I take fisetin every day?
Daily low-dose fisetin (100–200 mg) is used by some practitioners for its non-senolytic benefits (anti-inflammatory, neuroprotective). For senolytic purposes specifically, burst dosing (2 days on, extended time off) better mimics the evidence base.
Does fisetin cross the blood-brain barrier?
Yes. Animal studies demonstrate fisetin accumulation in brain tissue. This underlies its documented neuroprotective effects and the rationale for studying it in Alzheimer's disease .
Scientific References
- Yousefzadeh MJ et al. Fisetin is a senotherapeutic that extends health and lifespan. EBioMedicine. 2018. PMID: 30279143
- Maher P. Potentiation of glutathione loss and nerve cell death in vitro by the dietary constituent fisetin. Experimental Neurology. 2019