Does fisetin from strawberries really work as a zombie-cell cleaner?
Fisetin demonstrably clears zombie cells in lab and mouse research, but whether this also works in humans and is safe has not yet been established. Do not take it as a supplement outside clinical studies for the time being.
Fisetin is found in strawberries, but also in apples and onions. In laboratory research it was compared with nine other plant compounds. It turned out to be the most potent 'senolytic': a substance that selectively clears out aged, no-longer-functioning cells (also known as zombie cells). In cell cultures from both mice and humans, the hallmarks of such aged cells dropped measurably. Zombie cells also disappeared from human fat tissue1. Encouraging, but this is lab and tissue research, not a study in living people.
In mouse studies the results are strikingly consistent. Old mice that received fisetin late in life lived longer on average and reached a higher maximum age. Their tissue health improved and age-related abnormalities decreased1. Another mouse study showed that an alternating schedule (one week of fisetin, two weeks off, one week of fisetin) reduced arterial stiffness and improved blood vessel function2. Age-related changes in blood proteins also reversed after a short-term treatment3. These findings have been replicated across multiple studies, but mouse results do not automatically translate to humans.
In humans, the research is still at a very early stage. Clinical trials are underway in an early phase, but definitive conclusions about safety, dosing and efficacy in humans are not yet available4. Small pilot studies with senolytic agents in general, including fisetin, show positive signals: fewer zombie cells, lower inflammation markers and fewer complaints of frailty in older adults5. The researchers conducting these trials explicitly state that use outside controlled studies is premature for now.
There are also safety questions. Senolytics as a class have been associated with platelet deficiency. The dosing schedule (continuous or with breaks) also affects both efficacy and side effects6. For fisetin in humans, side effects have not yet been sufficiently studied and the optimal dose is unknown. Anyone taking fisetin as a supplement is getting ahead of the current evidence. There is also mouse research into fisetin in serious infections, but those are early animal study data with no clinical evidence in humans7.
Sources used: PMID 30279143 (mouse and tissue study, fisetin as a senolytic), PMID 38062873 (mouse study, arterial function), PMID 39658621 (mouse study, blood proteins), PMID 32686219 (early pilot studies in humans), PMID 39384074 (status of clinical trials of fisetin in humans), PMID 34108263 (mouse study, infection), PMID 40994903 (dosing and side effects of senolytics). No meta-analyses used as a direct source.
What do zombie cells do to your ageing?
Zombie cells accumulate as you age and accelerate ageing through inflammatory signals; how to tackle them is promising but still very much under investigation.
Does chronic inflammation accelerate the ageing of your cells?
Chronic inflammation demonstrably accelerates cellular ageing through a negative spiral that is difficult to break. The best evidence-based approach to tackling that spiral is through lifestyle factors that dampen low-grade inflammation, such as sufficient exercise and a diet low in ultra-processed products.
What does caffeine do to your cells and their repair processes?
Caffeine inhibits important DNA repair processes while simultaneously having protective effects in certain cell types, depending on context. The most concrete consequence for humans has now been demonstrated in blood transfusions: caffeine in donor blood measurably reduces the quality of stored red blood cells.
Do sirtuins actually do anything against ageing?
Sirtuins play a clear role in ageing in animal research, but whether they are of any benefit to humans (through supplements or other means) remains unknown. Wait for human evidence before acting on any sirtuin-based claims.
Does caloric restriction actually make your cells younger?
Caloric restriction slows ageing processes in cells, but whether your cells actually become younger as a result has not yet been proven in humans. The metabolic benefits, such as improved insulin sensitivity, have been demonstrated in human studies.
Does clearing senescent cells with senolytics help against ageing?
Senolytics show impressive results in mouse studies, but in humans the evidence is too thin for use outside clinical trials. Self-medication with Dasatinib is inadvisable due to its side effects and cancer-biology risks.