Fisetin: The Complete Evidence-Based Guide

Fisetin (3,3′,4′,7-tetrahydroxyflavone) is a naturally occurring flavonoid — a plant polyphenol found in various fruits and vegetables. It belongs to the same family as quercetin and kaempferol, but emerged as the most potent natural senolytic in a landmark 2018 Mayo Clinic study.

Senolytics are compounds that selectively clear senescent cells — damaged cells that stop dividing but resist death and accumulate with age. In a 2018 screening of 46 compounds, fisetin was the most potent natural candidate at reducing senescent cell viability.

No. Fisetin is classified as a dietary supplement under DSHEA and has not been evaluated or approved by the FDA to diagnose, treat, cure, or prevent any disease.

In preclinical research, fisetin has demonstrated senolytic activity (clearing senescent cells via BCL-2 family inhibition), anti-inflammatory effects (NF-κB inhibition), antioxidant activity (Nrf2 pathway activation), and mTOR/AMPK modulation.

Approximately 10–15 clinical trials are registered as of 2026, most in Phase I–II. The strongest evidence comes from preclinical studies showing lifespan extension in mice; human evidence is classified as early-stage/emerging.

Fisetin has been consumed through foods for millennia. In clinical trials, doses of 20 mg/kg/day for up to 2 consecutive days have been used without serious adverse events. Mild GI symptoms (nausea, diarrhea) are the most commonly reported side effects.

Strawberries are the richest source at approximately 160 μg/g fresh weight — 5–10× more than any other common food. Apples (26.9 μg/g), persimmons (10.5 μg/g), and onions (4.8 μg/g) follow. However, you'd need to eat roughly 8 pounds of strawberries to match a single research dose.

There is no established recommended dosage. Clinical trials have used approximately 20 mg/kg/day (roughly 1400 mg for a 70 kg adult) for 2 consecutive days in intermittent 'hit-and-run' protocols, followed by 28 days off.

Yes. A 2018 Mayo Clinic study identified fisetin as the most potent senolytic among 10 flavonoids tested in human cell culture, reducing senescent cell viability by 50–70%.

In naturally aging mice, late-life fisetin treatment extended both median and maximum lifespan by approximately 10%. No human lifespan studies have been conducted.

Both are flavonoid senolytics. Fisetin showed greater senolytic potency in the 2018 Mayo Clinic screening. Research suggests they may be synergistic when used together — fisetin for senescent cell clearance, quercetin for antioxidant support.

No. Typical Western dietary intake is 0.2–1.4 mg/day. Research doses are 1000× higher (1400+ mg). You'd need to consume approximately 8 pounds of strawberries to match a single senolytic research dose.

Fisetin's oral bioavailability is estimated at less than 10% due to poor water solubility and rapid hepatic metabolism. This is a key challenge in translating preclinical results to human applications.