Fisetin + Quercetin Stack: Synergistic Senolytic Protocol
Expert Summary
Fisetin preferentially inhibits BCL-XL and BCL-W; quercetin primarily inhibits BCL-2. Different senescent cell types preferentially rely on different BCL-2 family members for survival. Combining these two senolytic flavonoids on burst dosing days may achieve broader senescent cell clearance than either agent alone at equivalent individual doses.
Key Facts
- Complementary mechanisms: Fisetin + quercetin creates a "belt and suspenders" approach to BCL-2 inhibition. Fat senescent cells (adipocytes) rely heavily on BCL-XL (fisetin target); endothelial senescent cells rely more on BCL-2 (quercetin target).
- Evidence base: No human trial has specifically compared fisetin+quercetin vs either alone. The D+Q (dasatinib+quercetin) combination, however, demonstrates that combining BCL-2 targeting agents improves clinical outcomes vs historical quercetin-alone data.
- Dosing ratio: Common practitioner protocols use 500 mg fisetin + 500–1,000 mg quercetin on burst days. There is no clinically validated ratio; equal dosing by weight is a reasonable starting point.
- Bioavailability synergy: Both fisetin and quercetin benefit from fat co-administration. Taking the combination with a fat-containing meal efficiently optimizes both simultaneously. Phytosome forms of quercetin pair well with standard fisetin extract.
- Timing: Both can be taken simultaneously on burst days. Some protocols separate morning and evening doses to maintain plasma levels throughout the 2-day window.
- No known interactions: Fisetin and quercetin share metabolic pathways (CYP450, UGT) but at supplement doses, no clinically significant competitive interactions have been documented.
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Frequently Asked Questions
What is the best ratio of fisetin to quercetin?
No clinical ratio is established. Most practitioners use 1:1 to 1:2 (fisetin:quercetin) by mass. The D+Q protocol uses dasatinib 100 mg + quercetin 1,000 mg — quercetin-heavy. Natural-only protocols often use equal amounts of each flavonoid.
Can I add spermidine to the fisetin + quercetin stack?
Yes. Spermidine works through autophagy induction, complementing senolytic mechanisms. Daily spermidine (1–4 mg) maintained throughout the month, with fisetin + quercetin added on burst days, is a widely used protocol.
Should I cycle off quercetin or fisetin between burst days?
Many practitioners take low-dose quercetin (200–300 mg/day) continuously for its anti-inflammatory and cardiovascular benefits, using high-dose quercetin only on burst days for senolytic purposes. Fisetin is typically reserved for burst days only.
Scientific References
- Yousefzadeh MJ et al. Fisetin is a senotherapeutic that extends health and lifespan. EBioMedicine. 2018. PMID: 30279143
- Xu M et al. Senolytics improve physical function and increase lifespan. Nature Medicine. 2018. PMID: 29988130