Fisetin

The verdict

Is Fisetin worth taking?

Fisetin is the most accessible senolytic compound currently available without a prescription, and its safety profile is the best of any compound in the clinical senolytic trials. Senolytics are compounds that selectively destroy senescent cells, the zombie cells that accumulate with aging and drive chronic inflammation through their senescence-associated secretory phenotype. The animal evidence is strong. The human evidence is in active clinical trial phase with multiple randomized trials underway in osteoarthritis, peripheral artery disease, sepsis, and multimorbidity. No published RCT has yet demonstrated senolytic clearance in humans. The only human data is a 2024 Mayo Clinic self-report survey, not a controlled trial in 536 long-COVID patients where 64% of fisetin users reported significant symptom improvement.

What it does

What Fisetin does in the body

Selective elimination of senescent cells (senolytics), reduction of the senescence-associated secretory phenotype (SASP) that drives chronic inflammation, and downstream potential benefits for age-related conditions driven by senescent cell accumulation. Fisetin is a flavonol found naturally in strawberries, apples, and persimmons that has been shown in multiple animal models to reduce senescent cell burden in tissues including liver, lung, and brain, extend median lifespan, and attenuate age-related cognitive and physical decline.

The evidence

What the research actually shows

Emerging and in active clinical trial phase. A 2018 study in EBioMedicine found fisetin was the most potent senolytic of ten natural compounds tested, reducing senescent cell burden and extending median lifespan in mice. A 2024 Mayo Clinic observational study in 536 long-COVID patients found 64% of the 44 patients who received fisetin reported significant reduction in fatigue, muscle pain, and orthostatic hypotension. Multiple phase 2 randomized controlled trials are currently underway: STOP-Sepsis (n=220 elderly sepsis patients, 20 mg/kg for 1 to 2 days), FIRST trial in peripheral artery disease (Northwestern University), and a pilot trial in healthy volunteers and multimorbidity patients. No published RCT has yet confirmed senolytic cell clearance in humans.

The arithmetic

Why you cannot eat your way to a senolytic dose

Every article about fisetin opens with strawberries. Almost none of them does the multiplication.

Strawberries are the richest common food source, at roughly 160 micrograms per gram. A 100 gram serving, about seven medium berries, delivers at most around 16 milligrams of fisetin.

The senolytic trials are not working anywhere near that range. Protocols in the current phase 2 work use 20 milligrams per kilogram of body weight, pulsed over one to two days. For an 80 kilogram adult that is 1,600 milligrams in a day. Reaching it from strawberries would take about 10 kilograms of fruit, in one day, twice.

Put the other way round, a generous bowl of strawberries is roughly one percent of a single trial dose. Average dietary fisetin intake has been estimated at about 0.4 milligrams a day, which is four ten-thousandths of the amount being tested.

That gap is not a reason to dismiss the food. It is a reason to be precise about what the food is doing. Fisetin in a strawberry is one flavonol inside a polyphenol matrix, eaten at a dose with a long record of being good for people. Fisetin in a senolytic protocol is a pharmacological intervention being tested for a specific mechanism, at a dose no diet produces. They are different interventions that share a molecule, and the evidence for one does not transfer to the other.

Anyone telling you to eat strawberries for senolytic benefit has either not run the numbers or is hoping you will not.

Reading the marketing

How to read a fisetin sales page

Fisetin is sold into the longevity market, where the distance between what has been shown and what is implied is unusually wide. Four patterns recur.

Mouse lifespan presented as human lifespan. The 2018 work that put fisetin on the map tested ten natural compounds in mice and found fisetin the most potent senolytic among them, reducing senescent cell burden and extending median lifespan. That result is real and it is in mice. No published randomized controlled trial has yet demonstrated senescent cell clearance in humans.

The long-COVID survey quoted as a trial. A 2024 Mayo Clinic observational study of 536 long-COVID patients is cited constantly. Forty-four of those patients took fisetin and 64 percent reported improvement. That is a self-reported, uncontrolled subgroup of forty-four people. It is a reason to run a trial, not a result.

"Clinically studied" doing heavy lifting. Multiple phase 2 trials are genuinely underway, in sepsis, peripheral artery disease and multimorbidity. A compound being in trials is not a compound that has passed them. Watch for the word studied standing in for shown.

Silence about absorption. Fisetin is poorly water soluble and the human pharmacokinetics are thin. Any page quoting a milligram dose without addressing whether that dose arrives anywhere is skipping the part that decides whether the number means anything.

A page that states plainly that human efficacy is unproven, and still thinks the compound is worth watching, is being straight with you. Most do not.

Food first

Getting Fisetin from food

Strawberries are the richest common source by a wide margin. The figures most often quoted trace back to a 2000 analysis of flavonoid content in Japanese foods, which put strawberry at roughly 160 micrograms per gram. Everything else is an order of magnitude behind.

• Strawberry, about 160 µg/g. Up to about 16 mg in a 100 gram serving.
• Apple, about 27 µg/g. Concentrated in and just under the skin, so peeling costs most of it.
• Persimmon, about 10.5 µg/g.
• Lotus root, about 5.8 µg/g.
• Onion, about 4.8 µg/g.
• Grape, about 3.9 µg/g.
• Kiwifruit, about 2.0 µg/g.
• Peach, about 0.6 µg/g. Cucumber and tomato, about 0.1 µg/g.

Two things follow from that list, and both are kitchen decisions.

Do not peel the apple. Flavonols concentrate in the skin and the layer immediately beneath it. An apple peeled is an apple stripped of most of what put it on this list.

Heat and water are where it goes. Fisetin is a flavonol, and flavonols leach into cooking water and degrade with prolonged heat. Strawberries cooked into a compote or a jam are not delivering what raw strawberries deliver. If the fisetin is the reason you are eating them, eat them raw.

Freezing is the exception worth knowing. Strawberries picked ripe and frozen quickly hold their flavonol content better than fresh berries that have spent a week in transit and a few days in a refrigerator. Out of season, frozen is usually the better buy rather than the compromise.

What none of this adds up to is a senolytic dose, for the reasons above. The case for eating strawberries, apples with their skins on and onions is the ordinary case for eating them: a varied polyphenol intake across a long period is one of the better-supported dietary patterns there is. That case does not need fisetin to carry it, and fisetin does not need exaggerating to belong in the diet.

What the guide adds

The part that is not on this page

Everything above is the assessment. What the guide adds for Fisetin is the protocol:

• Optimal Form
• Bioavailability
• Purity Red Flags
• Stack With / Avoid

147 entries across nine categories, every one graded against the clinical literature the same way.

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About the author

Who graded this

Daniel Edlund is a Le Cordon Bleu-trained private chef in Los Angeles, a certified personal trainer and strength coach, and an internationally licensed massage therapist. Thirty years of strength training and fifteen years cooking in private estate kitchens. He is the author of The Complete Supplement Guide, which grades 147 entries against the clinical literature, and of The EASY Way to Organic Cooking, first published in 2013.

More about Daniel →

This page is information, not medical advice. Supplements interact with prescription medication and with each other, and the right answer depends on your own bloodwork and history. Talk to your doctor before starting anything, particularly if you are pregnant, nursing, managing a health condition, or already taking medication.

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