What is Quercetin & Fisetin?
Quercetin and Fisetin are flavonoid polyphenols found in foods (onions, apples, strawberries) and supplements. They have shown senolytic activity in preclinical research — inducing apoptosis in senescent cells while sparing healthy cells, potentially by targeting Bcl-2 family pathways.
Key Points
- •High-dose protocols — senolytic effects may require doses above typical dietary intake
- •Cycling — often used in "hit and run" protocols: high dose for 2–3 days, then 30 days off
- •Combination — sometimes combined with other senolytics (e.g., dasatinib) in research
Why do Quercetin & Fisetin matter?
Quercetin and fisetin matter because they are natural plant compounds being studied as possible senolytics, substances that may help clear aging, dysfunctional "senescent" cells. These cells build up with age and release inflammatory signals.
Quercetin is found in foods such as onions, apples, and capers, while fisetin occurs in smaller amounts in strawberries and some other fruits. Interest in both grew after promising results in laboratory and animal studies.
What affects Quercetin & Fisetin?
Several factors affect how quercetin and fisetin behave in the body. Both are poorly absorbed and quickly broken down, so the amount that reaches tissues is much lower than the amount eaten. Food form, the rest of the meal, and gut bacteria all influence uptake.
Their potential senolytic effects also depend on context. In research, quercetin has often been tested together with a cancer drug, dasatinib, rather than on its own. Human studies are still early-stage, small, and short, and they have not shown clear, lasting health benefits. Both compounds can also interact with some medications. For these reasons, their role in human aging remains unproven.
In ONDA Life
The Senolytic High-Dosing article covers quercetin/fisetin protocols.