Most fisetin protocols discussed online are built around large, intermittent doses: a gram or more for two or three days, then nothing for weeks. A human trial published as a protocol in 2026 tests the opposite idea. It gives adults aged 50 and over 100 mg of fisetin once a day for seven weeks, against placebo, and measures whether a marker of chronic inflammation called suPAR changes [1].
This is a protocol paper, so there are no results yet. What it does offer is a clear look at how researchers are now choosing to test fisetin in people, and two design choices that say a lot about the state of the evidence: the dose, and the decision to make adverse events a formal outcome.
Key Takeaways
- A triple-blind, randomised, placebo-controlled trial will give adults aged 50 and over 100 mg of fisetin or placebo once daily for seven weeks.
- The primary outcome is the change in plasma suPAR, a blood marker proposed as a measure of low-grade chronic inflammation.
- The secondary outcome is the occurrence and severity of adverse events, a sign of how thin the systematic human safety record for fisetin still is.
- The 100 mg dose is roughly a fourteenth of the pulsed dose used in the TROFFi trial, and the field has not settled on a dose.
- The paper describes a trial design. It reports no results, and nothing in it shows fisetin lowers inflammation in people.
Important: This article describes a trial design, not trial results, and is not medical advice. Fisetin has not been shown to lower inflammation, slow aging or prevent any disease in humans. Fisetin can inhibit drug-metabolising enzymes and may interact with prescription medicines, including anticoagulants. Speak to a doctor or pharmacist before taking it.
What the trial will do
The study is a triple-blind, randomised, placebo-controlled trial in generally healthy middle-aged and older adults [1]. Triple-blind means that participants, the people running the trial, and the people analysing the data are all kept unaware of who received fisetin. Participants aged 50 and over are randomised to 100 mg of oral fisetin or placebo, once daily, for seven weeks.
The primary outcome is the between-group difference in the change in plasma suPAR from baseline to week 7. The secondary outcome is the between-group difference in the occurrence and severity of adverse events. Exploratory outcomes cover other soluble and cellular markers of inflammation, aging and cellular senescence, plus measures of frailty, physical and cognitive function, and subjective health [1].
The authors frame the starting point plainly. Fisetin has anti-inflammatory, antioxidant and senolytic effects in cell and animal models, but evidence from randomised controlled trials in humans is limited [1]. The trial exists to add some.
What suPAR is, and why it was chosen
suPAR stands for soluble urokinase plasminogen activator receptor, a protein released into the blood when the immune system is activated. A 2021 review argues that it works as a marker of systemic chronic inflammation, the persistent, low-grade inflammation linked to many age-related diseases, and lays out ten properties the two share [2].
Two of those properties explain why a supplement trial would pick it. First, the review notes that suPAR is minimally affected by acute changes and short-term influences, unlike many markers in routine use such as CRP and IL-6, which can jump with a cold or a hard workout. Second, suPAR levels can be reduced by anti-inflammatory interventions and treatment of disease [2]. A marker that is stable day to day but still able to move is what a seven-week trial needs.
There is also population data tying it to aging itself. In the Dunedin Study, a New Zealand birth cohort, plasma suPAR was measured in 875 participants at age 45. Higher suPAR was associated with a faster pace of biological aging across multiple organ systems, an older facial appearance and structural signs of an older brain, after adjusting for CRP and other factors [3]. Participants who stopped smoking or became more active between ages 38 and 45 showed smaller rises in suPAR over those years.
None of that makes suPAR a proven target. It is an association marker, and a change in suPAR is not the same thing as a change in health. It is, however, a reasonable choice for asking whether a daily supplement shifts chronic inflammation at all.
Why adverse events are a formal endpoint
Making the occurrence and severity of adverse events a named secondary outcome is an unusual amount of emphasis for a nutritional supplement trial [1]. It is also an honest reflection of how little systematic human safety data fisetin has.
Look at what exists. The first human pharmacokinetic study gave fifteen healthy volunteers a single dose and followed them for twelve hours, reporting no adverse events [4]. The colorectal cancer trial gave 100 mg a day to eighteen people for seven weeks [5]. Reassuring results in small, short studies are not the same as a measured safety profile, and that gap is why this trial counts side effects deliberately rather than only noting them if they occur. Our side effects overview and the page on safety in older adults cover what is and is not known today.
Where 100 mg sits among the human trials
The dose is the most interesting design choice. It matches the colorectal cancer trial, which also used 100 mg daily for seven weeks [5]. It is half the 200 mg per day used in a 2026 exercise trial in men with obesity [6]. And it is a small fraction of the TROFFi trial in breast cancer survivors, which gives 20 mg/kg/day on days 1 to 3 of a fourteen-day cycle [7]. For a 70 kg person that is about 1,400 mg a day, roughly fourteen times this trial’s daily dose.
These are not small variations on one protocol. They reflect two different theories of how fisetin might work. Short, high-dose pulses follow the senolytic logic of clearing senescent cells and then stopping, which is explained in our guide to pulse dosing. A modest daily dose tests something closer to a steady anti-inflammatory effect, and it is also much closer to how most people actually take fisetin from a bottle.
Absorption complicates both. In the pharmacokinetic study, 1,000 mg of unformulated fisetin produced a peak plasma concentration of 9.97 ng/mL [4]. If 100 mg of a conventional product reaches the blood at a similar rate, exposure in this trial will be low, and the protocol abstract does not say whether a formulated product is being used.
What a result would and would not mean
If suPAR falls more with fisetin than with placebo, that would be one of the few placebo-controlled signals that fisetin changes an inflammation marker in healthy older adults. It would still be a biomarker result over seven weeks. It would not show that fisetin slows aging, prevents disease or extends life.
If suPAR does not change, that would not show fisetin is useless either. It would show that 100 mg a day for seven weeks, in this population, did not move this marker. It would say nothing about pulsed high doses, about other outcomes, or about formulations that absorb better.
Either way, the adverse event data may end up being the more useful half. A placebo-controlled count of side effects in older adults taking fisetin daily for seven weeks is something the field currently lacks.
What to do with this now
Nothing, yet. A protocol tells you what is being asked, not what was found, and a supplement decision should not be built on a trial that has not reported. What it does justify is scepticism toward any claim that the right fisetin dose is settled. The researchers designing human trials have not settled it, and the dosing research to date points in several directions at once.
Common questions
Has this low-dose fisetin trial reported results?
No. The 2026 paper is a study protocol describing the design: 100 mg of fisetin or placebo once daily for seven weeks in adults aged 50 and over [1]. Results have not been published.
What is suPAR?
Soluble urokinase plasminogen activator receptor, a blood protein released with immune activation. A 2021 review proposed it as a marker of systemic chronic inflammation because it is stable against short-term influences yet can be lowered by anti-inflammatory treatment [2].
Why does the trial use only 100 mg?
The paper describes it as low-dose supplementation and does not argue for a particular dose in its abstract. It matches the 100 mg daily dose of the earlier colorectal cancer trial [5] and is far below the pulsed 20 mg/kg/day used in TROFFi [7].
Is fisetin safe at 100 mg a day?
Small, short human studies have not reported serious problems, but no trial has yet published a systematic, placebo-controlled count of side effects in healthy older adults. Measuring that is the secondary aim of this trial [1].
Should I take 100 mg of fisetin based on this trial?
This trial gives no basis for it yet, because it has not reported. Speak to a doctor first, particularly if you take prescription medicines, since fisetin can affect drug-metabolising enzymes.
References
- Low-Dose Fisetin Supplementation and Its Association With Chronic Inflammation in Middle-Aged and Older Adults: Study Protocol for a Triple-Blind, Randomised, Placebo-Controlled Trial. Basic Clin Pharmacol Toxicol (2026). PMID 42633989
- Soluble Urokinase Plasminogen Activator Receptor (suPAR) as a Biomarker of Systemic Chronic Inflammation. Front Immunol (2021). PMID 34925360
- Association Between Elevated suPAR, a New Biomarker of Inflammation, and Accelerated Aging. J Gerontol A Biol Sci Med Sci (2021). PMID 32766674
- Enhanced bioavailability and pharmacokinetics of a novel hybrid-hydrogel formulation of fisetin orally administered in healthy individuals: a randomised double-blinded comparative crossover study. J Nutr Sci (2022). PMID 36304817
- Effect of fisetin supplementation on inflammatory factors and matrix metalloproteinase enzymes in colorectal cancer patients. Food Funct (2018). PMID 29541713
- 12-weeks fisetin supplementation and interval resistance with aerobic training: changes in Maresin-1 and inflammatory markers in men with obesity: a randomized controlled trial. J Int Soc Sports Nutr (2026). PMID 42218768
- A phase II randomized placebo-controlled study of fisetin to improve physical function in breast cancer survivors: the TROFFi study rationale and trial design. Ther Adv Med Oncol (2026). PMID 41835341
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.