Fisetin

What is Fisetin?

Fisetin is a flavonoid found in strawberries, apples, persimmons, onions and cucumbers, best known in longevity research as a "senolytic" — a compound that selectively helps clear senescent cells. Senescent cells are damaged cells that stop dividing but don't die off as they should; instead they accumulate with age and release inflammatory signals (the "senescence-associated secretory phenotype," or SASP) that are believed to drive chronic inflammation and tissue dysfunction.

Why Senolytics Matter

Clearing senescent cells in aged mice has repeatedly been shown to improve physical function, extend healthspan and, in some studies, lifespan. Fisetin was identified in a widely cited screening study as one of the most potent natural senolytics tested, and it's now one of the lead compounds being studied by the Mayo Clinic's aging research program, including trials looking at intermittent high-dose "hit-and-run" dosing protocols rather than continuous daily use — the theory being that senolytics need to be present only long enough to trigger clearance of senescent cells, not taken as a constant supplement.

Human Evidence

Human trials are earlier-stage than the animal data, with active studies underway examining fisetin's effects on frailty, bone health and inflammatory markers in older adults. As with the other senolytic and longevity compounds on this list, fisetin sits in an exciting but still-developing evidence category — strong mechanistic rationale and animal data, with human outcome trials still in progress.

Dosing Guidelines

• Research protocols have generally used intermittent, higher-dose "pulsed" schedules (e.g. several consecutive days per month) rather than daily continuous dosing — reflecting the senolytic "hit-and-run" theory
• Look for: a bioavailability-enhanced formulation (fisetin has naturally low absorption) — liposomal or phytosome forms are common
• Often discussed alongside quercetin as a complementary senolytic pairing
• Consult a doctor before starting, particularly around dosing schedule, since this differs from typical daily-supplement use