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Fisetin

Longevity

LimitedLittle human data, early, small, or narrow.

A strawberry flavonoid with striking mouse data and, so far, almost no human data.

No lifespan effect on retest
NIA Interventions Testing Program (Harrison et al. 2024) found no significant lifespan extension in either sex

What it is

A flavonoid pigment found in small amounts in strawberries, apples and onions, sold as a senolytic, a compound intended to clear worn-out "senescent" cells that accumulate with age and leak inflammatory signals. The supplement case rests principally on preclinical work whose lifespan results are mixed: the famous 2018 mouse study was positive, and the independent programme that later retested it was not.

How it works

Cells that are too damaged to divide but refuse to die accumulate as you age, and they secrete a stream of inflammatory molecules that degrade the tissue around them. Senolytics are meant to push those cells into dying. In a laboratory screen of flavonoids, fisetin was the most effective at doing this, and in mice it extended remaining lifespan even when started late in life. Whether any of that transfers to people is the open question, and it is genuinely open.

Which form to buy

Standard fisetin powder or capsuleMost of what is sold

Typically 98% pure extract, usually from the Chinese waxtree rather than strawberries. Poorly absorbed and cleared quickly, which is the core problem with the whole category.

What the mouse work used in principle, but the absorption gap between species is unresolved.

Liposomal or phospholipid-complexed fisetinAbsorption

Wrapped in fat to improve uptake. Laboratory and animal work supports better absorption; no human trial has shown that better absorption produces a better outcome.

Addresses a real weakness, but the endpoint it is meant to improve has not been demonstrated in people.

Dietary fisetin (strawberries)Context, not dosing

Strawberries are the richest food source and still contain a tiny fraction of a supplement dose, you cannot eat your way to the studied amounts.

Worth knowing so the "it is just a strawberry compound" framing does not mislead you.

What it actually does, graded

Extends lifespan in miceLimited

Mixed, and this is the crux. The 2018 study that made fisetin famous was positive with roughly 8-9 mice per late-life group. The NIA Interventions Testing Program, the most rigorous independent replication programme in the field, found no significant lifespan effect in either sex at the dose and schedule it used.

Reduces senescent cell burden in animal tissueModerate

Better supported than the lifespan claim, and still animal work.

Clears senescent cells in humansNone shown

No published trial demonstrates this endpoint in people. The human trials that exist measured other things entirely.

Changed selected inflammatory markers in small trialsLimited

Small randomised trials have reported shifts in markers such as IL-6 and TNF-alpha. These are biomarker studies in small groups, not evidence of a clinical anti-inflammatory effect.

Improves any human ageing outcomeNone shown

No trial has tested an ageing outcome in people. The human trials that exist studied unrelated conditions, and two of them missed their primary outcome.

Pros and cons

Pros
  • The senolytic screen that identified it was rigorous, and the mechanism is a serious research idea
  • Cheap relative to other longevity compounds
  • Human trials have started to appear, so the picture should keep improving
  • Short-term tolerability at ordinary doses appears good
Cons
  • The independent NIA replication programme found no mouse lifespan extension, which undercuts the compound's entire premise
  • Absorption in people is poor and the mouse-to-human dose translation is guesswork
  • Human safety data for the high intermittent protocols is limited to one small trial; nausea, headache, dry mouth and joint pain were reported
  • Sold with longevity claims the evidence does not currently support

What to expect

  • Honestly: nothing you can measure. There is no validated human marker of senescent cell clearance available to you, and no trial has reported a felt effect.
  • Anyone promising you a perceptible result is selling ahead of the evidence.
  • The human trials that have reported so far studied stroke, Gulf War illness and knee osteoarthritis, and the last two missed their primary outcomes. None of them was about ageing.

Interactions

CautionAnticoagulants and antiplatelet drugsFlavonoids as a class have platelet effects in laboratory work. Not established clinically for fisetin specifically, but the high intermittent doses used here are far above dietary intake.
CautionDrugs cleared by CYP enzymesFlavonoids commonly inhibit these liver enzymes in laboratory work, which can raise levels of other medicines. Poorly characterised for fisetin at supplement doses.
CautionOther senolytics (quercetin, dasatinib)Frequently stacked in imitation of research protocols. Dasatinib is a prescription cancer drug and does not belong in a self-directed stack.

Is it for you?

Probably worth it if
  • You knowingly want an early bet on mixed preclinical evidence and can afford for it to be worth nothing
  • You are tracking the human trial literature and want to be ready when it reports
Probably skip it if
  • You want evidence it does anything for ageing in people, no trial has tested that
  • You are copying a high intermittent mouse-derived protocol without a clinician, the human safety data behind it is one small trial
  • You are on anticoagulants or drugs with a narrow therapeutic window

Who should avoid it

  • Anyone pregnant or breastfeeding, no safety data exists
  • Anyone stacking it with prescription senolytics like dasatinib outside a trial

Research on this supplement

Papers about this supplement, not proof of the claims above. A title says what was studied, which is sometimes a negative result or a different question entirely.

What the evidence says

Fisetin was the most potent flavonoid in the senolytic screen that made it famous, and extended lifespan in the widely-cited 2018 mouse work. The independent NIA Interventions Testing Program then tested it and found NO significant lifespan extension in either sex at the dose and schedule used, which is the single most important fact about this compound and is rarely mentioned where it is sold. Human trials do exist (in stroke as an add-on, in Gulf War illness, and in knee osteoarthritis) but none tested senescent-cell clearance or ageing, and the last two did not find a benefit on their primary outcomes.

What studies used

Human trials are ongoing; no established supplemental dose exists. Published studies had not established a preferred timing.

Reported from published studies and product labelling — a record of what was used in research, not a recommendation. What is right for you is a conversation with a clinician.

Watch out for

  • The human safety profile at the high intermittent doses people copy from mouse studies is not established

Evidence base

B1,636 research papers
established literature

Real human evidence: randomised trial reports, or review-level evidence backed by at least one human trial report.

This letter measures how much human research exists, not whether it works for you — the tier above (Limited) is the read on quality.

Research (12)

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Where next

Every supplement in the catalogThe full shelf, grouped and evidence-tiered.→The compound indexSteroids, nootropics and research chemicals.→The peptide indexInjectable peptides and what trials used.→