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.

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.