Fisetin

Supplements · Antioxidants · Supplement, Typed Supps

A plant compound being studied for clearing out worn-out cells, though almost all the exciting evidence so far is in mice, not people.

Stage by stage

Intake (Capsule or dietary source): Taken orally as an extract, or consumed in foods like strawberries.
Small intestine (Limited absorption): Poorly and variably absorbed; much is metabolized before reaching circulation.
Bloodstream (Circulates): What is absorbed travels to tissues throughout the body.
Senescent cell clearance (Emerging research area): Studied in mice for selectively clearing aged, damaged cells — not yet confirmed in people.

What the evidence supports

Clearing senescent ('zombie') cells and supporting healthy aging — insufficient evidence. Fisetin's senolytic reputation comes almost entirely from cell-culture and mouse studies. Human trials (in Alzheimer's disease, chronic kidney disease, osteoarthritis, and skilled-nursing COVID-19 cohorts) are still small, early-phase, and mostly testing safety and biomarkers rather than proving a clinical benefit.
General antioxidant and anti-inflammatory activity — limited evidence. Fisetin scavenges free radicals and modulates inflammatory signalling in lab and animal models; a handful of small human pharmacokinetic and biomarker studies exist, but there isn't yet a body of human outcome data to match the lab findings.
Evidence on Short-term tolerability at doses used in early clinical trials — moderate evidence. Early-phase human trials using pulsed doses (roughly 20mg/kg on two consecutive days) reported no significant adverse events, but fisetin's low oral bioavailability and rapid metabolism mean blood levels achieved in people may not match those used in the animal studies driving interest in it.

Typical dose

Consumer products commonly use 100–500mg per day; clinical senolytic trials have instead tested pulsed high doses (roughly 20mg/kg for 2 consecutive days, repeated periodically) rather than continuous daily dosing.

Upper limit: No established UL

Timing

Take with food to support absorption of this fat-soluble flavonoid; standardized human dosing protocols do not yet exist.

Time to effect

Unclear: No confirmed human time-to-effect exists for any senolytic or anti-aging outcome.

Common myth

“Fisetin is a proven senolytic anti-aging supplement in humans.” In reality: The strong evidence is in mice and cells. Human trials are still in early safety and biomarker phases — no trial has yet shown a senolytic or longevity benefit in people.