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What This Page Explains
Fisetin is a naturally occurring flavonoid — a type of polyphenolic plant compound — found in a variety of common fruits and vegetables. It belongs to the flavonol subclass, which also includes quercetin and kaempferol. The compound was first isolated in 1891 from the smoke tree, but significant scientific attention began in the early 2000s.
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Detailed Evidence
Fisetin (3,3′,4′,7-tetrahydroxyflavone) has the molecular formula C₁₅H₁₀O₆ and molecular weight of 286.24 g/mol. Among commonly consumed foods, strawberries are the richest source at approximately 160 μg/g, followed by apples (26.9 μg/g), persimmons (10.5 μg/g), and onions (4.8 μg/g). Typical Western dietary intake is estimated at only 0.2–1.4 mg/day.
Evidence Hierarchy
Systematic Reviews & Meta-Analyses
Multiple high-quality trials combined
Randomized Controlled Trials (RCTs)
Gold standard for treatment efficacy
Observational Studies
Can show associations, not causation
Case Reports & Expert Opinion
Hypothesis-generating only
Preclinical (Lab/Animal) Studies
Should NOT be extrapolated to humans
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Study Quality Indicators
Higher Quality Indicators
- Large sample size (hundreds to thousands)
- Randomized and blinded design
- Placebo-controlled comparison
- Published in peer-reviewed journals
- Replicated in multiple studies
- Registered trial protocol before starting
Lower Quality Indicators
- Small sample size (under 100)
- No control group or blinding
- Manufacturer-funded with conflicts
- Only animal/cell studies
- Never replicated
- Published in predatory journals
Important Limitations
- • Supplement research often has methodological limitations
- • Results from one study may not generalize to all people
- • Marketing claims often exceed what research supports
- • Absence of evidence is not evidence of absence
- • Individual response to supplements varies widely
Quick Answers
What is fisetin made from?
Fisetin is a naturally occurring plant compound (flavonoid) found in fruits and vegetables. Supplemental fisetin is typically extracted from plant sources or synthesized.
What is fisetin's chemical structure?
Fisetin (3,3′,4′,7-tetrahydroxyflavone) has molecular formula C₁₅H₁₀O₆, molecular weight 286.24 g/mol, with hydroxyl groups at positions 3, 7, 3′, and 4′.
Is fisetin a vitamin?
No. Fisetin is a flavonoid polyphenol, not a vitamin. It is not essential for life but has demonstrated biological activity in preclinical research.
When was fisetin discovered?
Fisetin was first isolated in 1891 from the smoke tree (Cotinus coggygria), with its chemical structure determined in 1896.
Which fruit has the most fisetin?
Strawberries contain the highest concentration at approximately 160 μg/g fresh weight — roughly 5 to 10 times more than any other common food source.
Is fisetin the same as flavonoid?
No. Fisetin is a specific flavonoid compound. Flavonoid is the broader class of plant compounds that includes fisetin, quercetin, kaempferol, and many others.
Is fisetin natural or synthetic?
Fisetin occurs naturally in plants. Supplemental fisetin may be extracted from natural sources or synthesized to match the natural compound's structure.
How much fisetin is in an apple?
Apple skin contains approximately 26.9 μg/g of fisetin, making apples the second richest common food source after strawberries.
What makes fisetin different from other flavonoids?
Fisetin's specific hydroxylation pattern (positions 3, 7, 3′, and 4′) distinguishes it from other flavonoids and is thought to contribute to its unique biological activities, particularly its senolytic potency.
Is fisetin regulated?
Fisetin is classified as a dietary supplement under DSHEA in the US. It does not have FDA GRAS status and is not regulated to pharmaceutical standards.
Key Research Facts
Fisetin was first isolated from the smoke tree (Cotinus coggygria) in 1891, with its chemical structure determined in 1896.
Strong EvidenceGrynkiewicz & Demchuk, Frontiers in Chemistry — doi:10.3389/fchem.2019.00159
Strawberries contain approximately 160 μg/g of fisetin — the highest concentration of any commonly consumed food.
Strong EvidenceKhan et al., Antioxidants & Redox Signaling — doi:10.1089/ars.2012.4901
Fisetin (C₁₅H₁₀O₆) is a flavonol with molecular weight 286.24 g/mol and four hydroxyl groups at positions 3, 7, 3′, and 4′.
Strong EvidenceGrynkiewicz & Demchuk, Frontiers in Chemistry — doi:10.3389/fchem.2019.00159
Typical Western dietary fisetin intake is estimated at only 0.2–1.4 mg per day, far below clinical research doses.
Strong EvidenceKhan et al., Antioxidants & Redox Signaling — doi:10.1089/ars.2012.4901
Fisetin belongs to the flavonol subclass of flavonoids, alongside quercetin, kaempferol, and myricetin.
Strong EvidenceKhan et al., Antioxidants & Redox Signaling — doi:10.1089/ars.2012.4901
Unlike urolithin A, fisetin is a preformed dietary compound — consumed directly from food rather than produced by gut bacteria.
Strong EvidenceKhan et al., 2013
Fisetin is classified as a dietary supplement under DSHEA in the US and does not have FDA GRAS status.
Strong EvidenceFDA regulatory framework — DSHEA 1994
Citations & External Resources
ClinicalTrials.gov — Search: Fisetin
EBioMedicine — Yousefzadeh et al. 2018 (Landmark Senolytic Study)
Antioxidants & Redox Signaling — Khan et al. 2013 (Comprehensive Review)
Frontiers in Chemistry — Grynkiewicz & Demchuk 2019 (Chemistry Review)
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Related Reading
Fisetin: Overview, Evidence & Safety
How Fisetin Works: Senolytic Mechanisms
Fisetin Benefits: What the Evidence Shows
References (3)
Written by
ReCellence™ Editorial Team
Health Content Specialists
Medically reviewed by
Medical Review Board
MD, PhD
Last updated: March 8, 2026
Last medical review: March 8, 2026