Quercetin vs Fisetin: Comparing Senolytic Flavonoids

Fisetin showed stronger single-agent senolytic potency than quercetin in the 2018 Mayo Clinic screening. However, quercetin has more human senolytic data via the dasatinib+quercetin (D+Q) combination. Neither is proven superior in a head-to-head human trial.

Combining them has not been studied. Both have poor bioavailability and potential CYP interactions. There is no evidence for additive senolytic effects. Consult a healthcare provider before combining.

Quercetin has broad human evidence for antioxidant and anti-inflammatory effects, with hundreds of published trials. It's studied for allergy/immunity, cardiovascular health, exercise performance, and metabolic markers — a broader evidence base than fisetin.

Fisetin showed the highest senolytic index among 10 flavonoids in the 2018 screening, outperforming quercetin as a single agent. Its potential as a standalone senolytic (without dasatinib) is its key distinguishing feature.

Quercetin: 500–1,000 mg/day (or intermittent senolytic protocols with dasatinib). Fisetin: ~20 mg/kg/day for 2-day intermittent courses in trials. Doses and protocols differ — neither has established standard dosing.

Both have poor oral bioavailability (quercetin ~2%, fisetin ~5–10%). Quercetin has more developed enhanced formulations (piperine, phytosome) with some human PK validation. Fisetin's enhanced formulations are less clinically validated.

Quercetin has human senolytic data via the D+Q combination (diabetic kidney disease, IPF). Fisetin's human trials are primarily safety/tolerability; the AFFIRM trial (NCT03675724) is testing fisetin for frailty/inflammation in older adults.

Quercetin: onions (~300 μg/g), apples, capers, berries. Fisetin: strawberries (~160 μg/g), apples, persimmons. Dietary fisetin intake averages only 0.4 mg/day vs 10–50 mg/day for quercetin.

Both are generally well-tolerated. Quercetin has a longer safety history as a dietary supplement. Fisetin at 20 mg/kg for 2-day courses showed mild GI symptoms in early trials. Neither has serious adverse events documented at standard doses.

Both target anti-apoptotic pathways in senescent cells and inhibit NF-κB, but through partially distinct upstream kinase targets. Fisetin primarily inhibits BCL-xL; the D+Q combination targets a broader set of survival networks.

Senolytic protocols use intermittent 'hit-and-run' dosing (2–3 days/month) rather than continuous daily supplementation, based on the hypothesis that brief exposure triggers senescent cell apoptosis without needing sustained drug levels.

Quercetin has substantially more published studies overall (~20,000 PubMed entries vs ~2,000 for fisetin), including more cancer-related research. Neither is approved as a cancer treatment.

The D+Q combination reduced senescent cell burden in human adipose tissue (Hickson 2019). Fisetin's senolytic activity in humans is still being validated. Preclinical data is strong; human confirmation is ongoing.

Both inhibit NF-κB signaling in cell culture. Quercetin has more published human anti-inflammatory biomarker data (CRP, IL-6), though results are inconsistent. Neither has robust clinical anti-inflammatory evidence as monotherapy.

Quercetin has approximately 20,000 PubMed entries versus 2,000 for fisetin, reflecting a much longer research history. Fisetin's senolytic research is newer and more focused.