What is fisetin and what does it do?

Fisetin is a flavonoid found in plants, with strawberries the richest food source. In the lab and in mice it acts as a senolytic, a compound that helps clear senescent cells, the worn-out cells that build up with age and give off inflammatory signals. That mechanism is why it draws so much longevity interest.

Does fisetin extend lifespan?

In mice, yes: given late in life, fisetin extended median and maximum lifespan in a 2018 study. In people there is no lifespan or mortality data at all. The animal finding is promising, but it has not been shown in humans, so treating fisetin as a proven longevity drug gets ahead of the evidence.

Is fisetin proven to work in humans?

Not yet. Several small human trials have run or are underway, including Mayo Clinic studies in older adults, but none has published a result showing a senolytic benefit. Today fisetin in people is a well-motivated hypothesis rather than a demonstrated therapy.

Can I get fisetin from food?

Yes, in small amounts. Strawberries are the richest source, followed by apples and persimmons. Food will not reach the doses used in senolytic research, but strawberries are a no-risk way to include fisetin as part of a plant-rich diet.

In the human trials so far, fisetin has been well tolerated at the doses tested, and animal work shows a wide safety margin. The unknowns are the long-term effects of repeated senolytic dosing, which have not been studied in people, and flavonoid interactions with blood thinners and some prescription drugs. Those are worth a conversation before starting.

Where does fisetin fit in a longevity plan?

I place it in the experimental tier, above unfounded gimmicks but below the levers with stronger human support. The foundations come first, then compounds with better evidence like urolithin A, taurine, and spermidine. Fisetin is a reasonable frontier experiment for someone who has the basics handled and understands they are ahead of the evidence.

What would change your mind about fisetin?

A well-run human trial with a meaningful clinical endpoint. The Mayo Clinic and other groups are studying fisetin in older adults, frailty, and other settings. If those trials show that senolytic dosing improves function or a disease outcome in people, fisetin moves up my list quickly. Until the results are published, I hold it as promising rather than proven.

What is fisetin and what does it do?

Fisetin is a flavonoid found in plants, with strawberries the richest food source. In the lab and in mice it acts as a senolytic, a compound that helps clear senescent cells, the worn-out cells that build up with age and give off inflammatory signals. That mechanism is why it draws so much longevity interest.

Does fisetin extend lifespan?

In mice, yes: given late in life, fisetin extended median and maximum lifespan in a 2018 study. In people there is no lifespan or mortality data at all. The animal finding is promising, but it has not been shown in humans, so treating fisetin as a proven longevity drug gets ahead of the evidence.

Is fisetin proven to work in humans?

Not yet. Several small human trials have run or are underway, including Mayo Clinic studies in older adults, but none has published a result showing a senolytic benefit. Today fisetin in people is a well-motivated hypothesis rather than a demonstrated therapy.

Can I get fisetin from food?

Yes, in small amounts. Strawberries are the richest source, followed by apples and persimmons. Food will not reach the doses used in senolytic research, but strawberries are a no-risk way to include fisetin as part of a plant-rich diet.

In the human trials so far, fisetin has been well tolerated at the doses tested, and animal work shows a wide safety margin. The unknowns are the long-term effects of repeated senolytic dosing, which have not been studied in people, and flavonoid interactions with blood thinners and some prescription drugs. Those are worth a conversation before starting.

Where does fisetin fit in a longevity plan?

I place it in the experimental tier, above unfounded gimmicks but below the levers with stronger human support. The foundations come first, then compounds with better evidence like urolithin A, taurine, and spermidine. Fisetin is a reasonable frontier experiment for someone who has the basics handled and understands they are ahead of the evidence.

What would change your mind about fisetin?

A well-run human trial with a meaningful clinical endpoint. The Mayo Clinic and other groups are studying fisetin in older adults, frailty, and other settings. If those trials show that senolytic dosing improves function or a disease outcome in people, fisetin moves up my list quickly. Until the results are published, I hold it as promising rather than proven.

Fisetin Clinical Guide: Senolytics, Aging, and What the Human Evidence Shows

TL;DR30-second take

Fisetin is a plant flavonoid, richest in strawberries, that acts as a senolytic, meaning it can clear worn-out senescent cells in the lab and in mice. In aged mice, fisetin reduced senescent-cell burden and, given late in life, extended lifespan. In people, the story is early: several small trials are underway, but no published human trial has yet shown a senolytic benefit, and unformulated fisetin is poorly absorbed. It appears well tolerated at studied doses. For now it is a promising idea to watch, with strawberries as the no-risk way to get some.

At Fishtown Medicine, fisetin is one of the compounds patients bring up after a longevity podcast, and I understand the pull. The senolytic idea behind it is a compelling one: clear out the aging cells that linger and stir up inflammation, and you might slow part of aging itself. The animal data is striking. My job is to set that next to what we know in people, which is far less than the marketing suggests, so you can decide whether fisetin earns a place in your plan or a spot on your watch list.

Want to sort hype from evidence on longevity supplements?

What fisetin is and what it does

Fisetin is a flavonoid, a plant pigment in the same broad family as quercetin. You eat small amounts of it every day, with strawberries the richest source by a wide margin, followed by apples and persimmons. What lifted fisetin out of the crowd of plant antioxidants was a 2018 screen of ten flavonoids for senolytic activity, in which fisetin came out the most potent.

To see why that matters, it helps to know about senescent cells. As you age, some cells stop dividing but refuse to die. They linger and give off a stew of inflammatory signals that researchers call the senescence-associated secretory phenotype, which nudges nearby healthy tissue toward dysfunction. These lingering cells are one of the recognized drivers of inflammaging, the slow rise in background inflammation that tracks with age. A senolytic is a compound that selectively pushes these cells to die off, ideally in short pulses rather than every day. The senolytic class began with a prescription pair, dasatinib plus quercetin, and fisetin arrived as a food-derived cousin.

In aged mice, intermittent fisetin lowered senescent-cell markers across several tissues, and when it was given later in life, it extended both median and maximum lifespan. That is a striking result in animals, and it is the source of nearly every headline you have seen. The leap the headlines skip is the one from mouse to person.

Who this is for (and who it isnt)

Fisetin tends to appeal to:

People drawn to the senolytic science. Anyone curious about clearing senescent cells who is willing to treat it as an experiment rather than a settled therapy.
Longevity-minded people with the basics handled. Those who already have sleep, strength, and cardiometabolic health in place and want to explore the frontier.
People who like a food-first entry. Strawberries carry fisetin along with fiber and other polyphenols, so there is a no-risk way to start.

It needs a conversation first, or isnt the right move, if:

You take blood thinners or antiplatelet drugs. Flavonoids can add to their effect, so a high-dose supplement deserves a prescriber's sign-off.
You are pregnant or breastfeeding. Fisetin has not been tested in these groups, so stay with food amounts.
You take medications with narrow margins. Fisetin can influence the same liver enzymes and transporters that process many drugs, so review it with whoever manages your prescriptions.
You want a proven anti-aging therapy today. The human evidence is not there yet, so buying it as a settled longevity treatment gets ahead of the data.

How we evaluate it: safety, then effectiveness, then cost

Every supplement we recommend runs the same three gates, in order (see how we choose supplements).

Safety first. In the small human trials run so far, fisetin has been well tolerated at the doses studied, and mouse work found no toxicity even at very high doses. The open questions are about the long run: no one yet knows the safety of clearing senescent cells repeatedly in people over years. Add the flavonoid interaction cautions above, choose a third-party-tested product, and you have covered the near-term risks.
Effectiveness second. This is where the picture thins out. The mechanism is strong and the mouse data is eye-catching, but no published human trial has shown a senolytic benefit. Several pilots are underway or completed, including Mayo Clinic trials in older adults with frailty, and their results are not yet published in a form that would let me tell you fisetin works in people. Until then, effectiveness in humans is a hypothesis rather than a finding.
Cost last. Capsules are inexpensive, and strawberries more so. The question worth asking is whether what is in the capsule reaches your bloodstream, which brings us to dosing.

How to dose it, and when

Here is the tension at the center of fisetin dosing.

What the trials use. The registered human senolytic trials use a pulse: about 20 milligrams per kilogram per day for two days in a row, then a long gap. For a 70-kilogram adult that works out to roughly 1,400 milligrams a day during the pulse.
What supplements provide. Most commercial fisetin is 100 to 500 milligrams a day taken continuously. That is both a smaller dose and a different schedule than anything tested as a senolytic.
The absorption problem. Even at 1,000 milligrams, plain fisetin barely registers in the blood in human testing, reaching a peak of only about 10 nanograms per milliliter, because it is poorly absorbed and rapidly cleared. Formulations built to improve absorption raise those levels substantially, which is worth looking for on a label.
If you still want to try it. Take it with a fat-containing meal to aid absorption, favor an enhanced-absorption formulation, and treat any senolytic-style pulse dosing as something to design with your physician rather than guess at.

Flaws, side effects, and interactions

Fishtown Medicine

A 90-minute conversation with Dr. Ash. A written plan you can actually follow.

Start your intake

Fisetin is well tolerated in the short human studies so far, with a few caveats to keep in mind:

The human evidence gap is the headline flaw. Strong mouse data and a clear mechanism have not yet produced a positive published human trial.
Poor bioavailability. Plain fisetin is absorbed poorly, so a standard capsule may deliver far less active compound than the milligram count implies.
Dose and schedule mismatch. The daily low-dose habit most people follow does not match the intermittent high-dose pulse used in senolytic research, so even a believer should not assume a capsule reproduces the trials.
Drug interactions. As a flavonoid, fisetin can affect drug-processing enzymes and add to blood thinners and antiplatelet agents. If you take prescription medicines, clear it with your prescriber first.
Unknown long-term safety. Clearing senescent cells is a young idea in humans, and the long-run effects of doing it repeatedly are not mapped.

We look for: strawberries first, as the zero-risk way to get some fisetin, and, for those who want to experiment, a third-party-tested, enhanced-absorption product used thoughtfully.
Worth considering alongside fisetin: the other cellular-maintenance levers that carry their own evidence. Spermidine and time-restricted eating support autophagy, urolithin A supports mitochondrial cleanup, and rapamycin targets the mTOR pathway as a monitored prescription. Fisetin sits in a more experimental tier than these.
We skip: proprietary longevity blends that tuck a pinch of fisetin into a long label, and any product promising it will reverse aging or clear your senescent cells, since no human trial supports that claim.

Guidance from the Clinic

"When a patient asks me about fisetin, my answer is that the animal data earned our attention and the human data has not caught up. I am not against it. I eat the strawberries, I keep an eye on the Mayo Clinic trials, and for the person who wants to experiment with an enhanced-absorption product, I would rather help design a sensible plan than have them guess from a podcast. What I will not do is sell it as a proven way to clear aging cells, because we do not have that proof in people yet. It is a promising idea that still has to prove itself where it counts, in a human being."

Dr. Ash

Actionable Steps

Treat fisetin as an experiment built on a strong base.

Eat the strawberries. They are the richest food source and carry fiber and other polyphenols, with no downside.
Get the foundations right first. Sleep, strength training, cardio, and cardiometabolic risk move the needle far more than any senolytic.
If you want to try a supplement, choose well. Look for third-party testing and an enhanced-absorption formulation, and take it with a meal that contains fat.
Loop in your physician about dose and schedule. This matters more if you take blood thinners or other prescriptions.
Follow the trials rather than the ads. The Mayo Clinic and other groups have human studies underway, and their published results will tell us far more than any supplement label.

Tell Dr. Ash what's going on

Key Takeaways

Fisetin is a plant flavonoid, richest in strawberries, that acts as a senolytic in the lab and in mice, clearing worn-out senescent cells that drive inflammation with age.
In aged mice, fisetin given late in life extended median and maximum lifespan, which is the basis for its longevity reputation.
No published human trial has yet shown a senolytic benefit; several pilots, including Mayo Clinic studies, are underway or awaiting results.
Plain fisetin is poorly absorbed, and typical supplement dosing (100 to 500 milligrams daily) differs in both amount and schedule from the intermittent high-dose pulses used in research.
It appears well tolerated short-term; approach it food-first with strawberries, use an enhanced-absorption product if you experiment, and review it with your physician if you take blood thinners or other prescriptions.

A note on cost: any discount we negotiate on professional-grade supplements passes straight through to you, with no markup. Here is how we choose and source supplements.

Scientific References

Yousefzadeh MJ, Zhu Y, McGowan SJ, et al. Fisetin is a senotherapeutic that extends health and lifespan. EBioMedicine. 2018;36:18-28.
Zhu Y, Doornebal EJ, Pirtskhalava T, et al. New agents that target senescent cells: the flavone, fisetin, and the BCL-XL inhibitors, A1331852 and A1155463. Aging (Albany NY). 2017;9(3):955-963.
Zhu Y, Tchkonia T, Pirtskhalava T, et al. The Achilles' heel of senescent cells: from transcriptome to senolytic drugs. Aging Cell. 2015;14(4):644-658.
Touil YS, Auzeil N, Boulinguez F, et al. Fisetin disposition and metabolism in mice: identification of geraldol as an active metabolite. Biochemical Pharmacology. 2011;82(11):1731-1739.
Joseph A, et al. Enhanced bioavailability and pharmacokinetics of a novel hybrid-hydrogel formulation of fisetin orally administered in healthy individuals: a randomised double-blinded comparative crossover study. Journal of Nutritional Science. 2022;11:e74.
Khan N, Syed DN, Ahmad N, Mukhtar H. Fisetin: a dietary antioxidant for health promotion. Antioxidants & Redox Signaling. 2013;19(2):151-162.
Verdoorn BP, et al. Fisetin for COVID-19 in skilled nursing facilities: senolytic trials in the COVID era. Journal of the American Geriatrics Society. 2021;69(11):3023-3033.
Tavenier J, Nehlin JO, Houlind MB, et al. Fisetin as a senotherapeutic agent: evidence and perspectives for age-related diseases. Mechanisms of Ageing and Development. 2024;222:111995.

Fishtown Medicine | Articles

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Frequently Asked Questions

Common Questions

There is no established human dose for a senolytic effect. Research trials use a short pulse of about 20 milligrams per kilogram for two days, which is far more than the 100 to 500 milligrams a day found in most supplements, and on a different schedule. If you choose to try it, an enhanced-absorption product taken with food makes more sense than a bare high dose, and the plan is worth reviewing with your physician.

Deep-Dive Questions

As you age, some cells stop dividing but do not die. They accumulate and secrete inflammatory and tissue-remodeling signals, a mix researchers call the senescence-associated secretory phenotype. This feeds inflammaging and several age-related conditions. The senolytic strategy is to clear these cells in short pulses, which improved function in aged mice. Whether it does the same in humans is the open question.

The senolytic class began with dasatinib plus quercetin, a prescription pairing used in research. Fisetin is a food-derived flavonoid that screened as the most potent senolytic among the flavonoids tested in laboratory studies. Its appeal is that it comes from the plate rather than the pharmacy, though that also means less oversight of dose and purity. None of these, fisetin included, has a positive published human senolytic trial yet.

Plain fisetin is absorbed poorly and cleared quickly. In human testing, even a 1,000-milligram dose reached a blood peak of only about 10 nanograms per milliliter. That gap between the dose you swallow and the amount that reaches your tissues is why formulation matters, and why a milligram count on a label does not tell you how much active compound your body will take up. Enhanced-absorption formulations raise blood levels substantially and are worth looking for.

It may matter a great deal. Senolytic research uses intermittent high-dose pulses, on the theory that you only need to knock back senescent cells periodically, then let the body rest. Most supplement users instead take a modest dose every day. These are different strategies, and the daily-habit approach has not been tested as a senolytic. If the pulse theory is right, continuous low dosing may miss the point.

Ready when you are

Start your intake

Dr. Ash reads every intake himself, and answers questions personally - usually within a few hours.

TL;DR30-second take

Want to sort hype from evidence on longevity supplements?

What fisetin is and what it does

Who this is for (and who it isnt)

Fisetin tends to appeal to:

People drawn to the senolytic science. Anyone curious about clearing senescent cells who is willing to treat it as an experiment rather than a settled therapy.
Longevity-minded people with the basics handled. Those who already have sleep, strength, and cardiometabolic health in place and want to explore the frontier.
People who like a food-first entry. Strawberries carry fisetin along with fiber and other polyphenols, so there is a no-risk way to start.

It needs a conversation first, or isnt the right move, if:

You take blood thinners or antiplatelet drugs. Flavonoids can add to their effect, so a high-dose supplement deserves a prescriber's sign-off.
You are pregnant or breastfeeding. Fisetin has not been tested in these groups, so stay with food amounts.
You take medications with narrow margins. Fisetin can influence the same liver enzymes and transporters that process many drugs, so review it with whoever manages your prescriptions.
You want a proven anti-aging therapy today. The human evidence is not there yet, so buying it as a settled longevity treatment gets ahead of the data.

How we evaluate it: safety, then effectiveness, then cost

Every supplement we recommend runs the same three gates, in order (see how we choose supplements).

Safety first. In the small human trials run so far, fisetin has been well tolerated at the doses studied, and mouse work found no toxicity even at very high doses. The open questions are about the long run: no one yet knows the safety of clearing senescent cells repeatedly in people over years. Add the flavonoid interaction cautions above, choose a third-party-tested product, and you have covered the near-term risks.
Effectiveness second. This is where the picture thins out. The mechanism is strong and the mouse data is eye-catching, but no published human trial has shown a senolytic benefit. Several pilots are underway or completed, including Mayo Clinic trials in older adults with frailty, and their results are not yet published in a form that would let me tell you fisetin works in people. Until then, effectiveness in humans is a hypothesis rather than a finding.
Cost last. Capsules are inexpensive, and strawberries more so. The question worth asking is whether what is in the capsule reaches your bloodstream, which brings us to dosing.

How to dose it, and when

Here is the tension at the center of fisetin dosing.

What the trials use. The registered human senolytic trials use a pulse: about 20 milligrams per kilogram per day for two days in a row, then a long gap. For a 70-kilogram adult that works out to roughly 1,400 milligrams a day during the pulse.
What supplements provide. Most commercial fisetin is 100 to 500 milligrams a day taken continuously. That is both a smaller dose and a different schedule than anything tested as a senolytic.
The absorption problem. Even at 1,000 milligrams, plain fisetin barely registers in the blood in human testing, reaching a peak of only about 10 nanograms per milliliter, because it is poorly absorbed and rapidly cleared. Formulations built to improve absorption raise those levels substantially, which is worth looking for on a label.
If you still want to try it. Take it with a fat-containing meal to aid absorption, favor an enhanced-absorption formulation, and treat any senolytic-style pulse dosing as something to design with your physician rather than guess at.

Flaws, side effects, and interactions

Fishtown Medicine

A 90-minute conversation with Dr. Ash. A written plan you can actually follow.

Start your intake

Fisetin is well tolerated in the short human studies so far, with a few caveats to keep in mind:

The human evidence gap is the headline flaw. Strong mouse data and a clear mechanism have not yet produced a positive published human trial.
Poor bioavailability. Plain fisetin is absorbed poorly, so a standard capsule may deliver far less active compound than the milligram count implies.
Dose and schedule mismatch. The daily low-dose habit most people follow does not match the intermittent high-dose pulse used in senolytic research, so even a believer should not assume a capsule reproduces the trials.
Drug interactions. As a flavonoid, fisetin can affect drug-processing enzymes and add to blood thinners and antiplatelet agents. If you take prescription medicines, clear it with your prescriber first.
Unknown long-term safety. Clearing senescent cells is a young idea in humans, and the long-run effects of doing it repeatedly are not mapped.

We look for: strawberries first, as the zero-risk way to get some fisetin, and, for those who want to experiment, a third-party-tested, enhanced-absorption product used thoughtfully.
Worth considering alongside fisetin: the other cellular-maintenance levers that carry their own evidence. Spermidine and time-restricted eating support autophagy, urolithin A supports mitochondrial cleanup, and rapamycin targets the mTOR pathway as a monitored prescription. Fisetin sits in a more experimental tier than these.
We skip: proprietary longevity blends that tuck a pinch of fisetin into a long label, and any product promising it will reverse aging or clear your senescent cells, since no human trial supports that claim.

Guidance from the Clinic

"When a patient asks me about fisetin, my answer is that the animal data earned our attention and the human data has not caught up. I am not against it. I eat the strawberries, I keep an eye on the Mayo Clinic trials, and for the person who wants to experiment with an enhanced-absorption product, I would rather help design a sensible plan than have them guess from a podcast. What I will not do is sell it as a proven way to clear aging cells, because we do not have that proof in people yet. It is a promising idea that still has to prove itself where it counts, in a human being."

Dr. Ash

Actionable Steps

Treat fisetin as an experiment built on a strong base.

Eat the strawberries. They are the richest food source and carry fiber and other polyphenols, with no downside.
Get the foundations right first. Sleep, strength training, cardio, and cardiometabolic risk move the needle far more than any senolytic.
If you want to try a supplement, choose well. Look for third-party testing and an enhanced-absorption formulation, and take it with a meal that contains fat.
Loop in your physician about dose and schedule. This matters more if you take blood thinners or other prescriptions.
Follow the trials rather than the ads. The Mayo Clinic and other groups have human studies underway, and their published results will tell us far more than any supplement label.

Tell Dr. Ash what's going on

Key Takeaways

Fisetin is a plant flavonoid, richest in strawberries, that acts as a senolytic in the lab and in mice, clearing worn-out senescent cells that drive inflammation with age.
In aged mice, fisetin given late in life extended median and maximum lifespan, which is the basis for its longevity reputation.
No published human trial has yet shown a senolytic benefit; several pilots, including Mayo Clinic studies, are underway or awaiting results.
Plain fisetin is poorly absorbed, and typical supplement dosing (100 to 500 milligrams daily) differs in both amount and schedule from the intermittent high-dose pulses used in research.
It appears well tolerated short-term; approach it food-first with strawberries, use an enhanced-absorption product if you experiment, and review it with your physician if you take blood thinners or other prescriptions.

A note on cost: any discount we negotiate on professional-grade supplements passes straight through to you, with no markup. Here is how we choose and source supplements.