Most of what you read about fisetin comes from mice. We wanted the human part, so we searched PubMed and the U.S. trial registry for studies in people, and wrote down what each one found and what it did not.
By BoneScience Editorial · Sources checked against PubMed abstracts and ClinicalTrials.gov on November 8, 2026 · Last reviewed November 8, 2026
What fisetin is
Fisetin (3,3′,4′,7-tetrahydroxyflavone) is a flavonol, a plant pigment in the same flavonoid family as quercetin. It occurs naturally in strawberries, apples, persimmons, grapes, onions and cucumbers.
What the lab studies suggest (mice and cells)
This section is about mice and lab dishes, not people. In a 2018 study, researchers tested 10 flavonoids on senescent cells, cells that have stopped dividing after stress and are sometimes nicknamed "zombie cells." Fisetin was the most active at clearing them, which is why it is called a senolytic. Old mice given fisetin late in life had fewer senescence markers, less age-related tissue damage, and a longer median and maximum lifespan. A separate test-tube study using human liver tissue found that fisetin blocks CYP2C8, an enzyme the liver uses to clear some medicines. Neither result has been tested in living people.
What the human studies found
These are the studies we could verify in which people took fisetin by mouth and results were published. The longest daily study with a placebo group ran 12 weeks.
| Study | Who and how long | Daily fisetin | What it found | What it did not find |
|---|---|---|---|---|
| Alipour 2026 (two reports, one trial) | 60 men with obesity in Iran, 12 weeks, four groups (placebo, fisetin, exercise plus placebo, exercise plus fisetin). 44 finished, about 11 per group. | 200 mg | In the fisetin-only group, two blood markers of inflammation (IL-6 and TNF-alpha) fell, as did fasting glucose and insulin. Changes were largest with exercise plus fisetin. No adverse events. | Maresin-1, the main marker, rose only in the exercise groups. 16 of 60 men dropped out. Men only, one country. Several results are changes within a group, not differences from placebo. |
| Krishnakumar 2022 | 15 healthy adults aged 22 to 55, one dose of each of two forms (crossover) | 1,000 mg plain fisetin, or 1,000 mg of a fiber-gel form holding 192 mg | Blood fisetin over 12 hours was 26.9 times higher with the fiber-gel form. Peak level was 238.2 vs 9.97 ng/mL. No adverse events. | One dose. It measured blood levels, not health effects. Funded by the maker of the fiber-gel form. |
| Hodgin 2021 | 11 male veterans with Gulf War illness, one month per dose, compared with a placebo month | 200 mg, then 800 mg | Nothing beyond placebo. Side effects were mild to moderate; two men reported more fatigue on 800 mg. | Symptom, pain and fatigue scores did not improve more than placebo at either dose. |
| Lee 2024 | 10 healthy adults over 50, 6 months, no placebo group | 500 mg a day, one week each month | On a blood test of "biological age," 4 of 10 people went down. No adverse effects. | 5 of 10 went up. Telomere length did not change. The authors advised against taking fisetin for this until larger studies are done. |
A 2026 review of trial registries found 34 registered fisetin trials. Six were completed and four had results. The reviewers called the clinical evidence limited and mixed, with small samples and combined interventions that make it hard to credit fisetin itself.
Fisetin bioavailability: why the form matters
Bioavailability means how much of what you swallow reaches your blood. For plain fisetin it appears to be low. In the 2022 crossover study, 15 adults took 1,000 mg of plain fisetin on one day and 1,000 mg of a formulated powder on another. The formulated powder held only 192 mg of fisetin, packed into a fenugreek fiber gel. Yet blood fisetin over 12 hours was 26.9 times higher, and the peak was more than 23 times higher. The authors called it the first human pharmacokinetic study of fisetin.
A higher blood level is not a health effect, and the maker of the formulated ingredient funded the study. Other formulas add phospholipids or black pepper extract; we did not find a published human study measuring fisetin absorption with those. A registered German study, FISEKIN-1, plans to compare blood fisetin in younger and older adults, with and without food. It was recruiting as of November 2026.
Fisetin dosage: what the studies used
| Amount | Schedule | Study |
|---|---|---|
| 100 mg | Daily for 7 weeks | Danish placebo-controlled trial, recruiting |
| 100 mg | Daily for 60 days | Steadman Philippon trial, no results posted |
| 200 mg | Daily for 12 weeks | Alipour 2026 |
| 200 mg, then 800 mg | Daily, one month each | Hodgin 2021 |
| 500 mg | Daily for one week a month, 6 months | Lee 2024 |
| 1,000 mg | Single dose of plain fisetin | Krishnakumar 2022 |
| About 20 mg per kg of body weight | Two days in a row, sometimes repeated monthly | Mayo Clinic AFFIRM trials, no results posted |
Published daily studies used 200 to 800 mg; two registered trials are testing 100 mg. The Mayo Clinic trials instead give a large dose two days in a row; for a 70 kg (154 lb) adult, 20 mg per kg is about 1,400 mg a day. One completed trial compared 100 mg daily with the two-day schedule, but it has posted no results.
Fisetin side effects and safety
The 12-week trial, the single-dose study and the 10-person pilot each reported no adverse events. In the veterans' trial, side effects were mild to moderate, and two of 11 men reported more fatigue on 800 mg a day. Fewer than 100 people took fisetin in all four studies combined, and no placebo-controlled study gave it daily for longer than 12 weeks. None included pregnant or breastfeeding women or children. The liver-enzyme result from the lab has not been checked in people, so if you take prescription medicine, ask your doctor or pharmacist first.
Registered trials still waiting for results
Status as listed on ClinicalTrials.gov on November 8, 2026. We found no published fisetin results for any of them.
- AFFIRM and AFFIRM-LITE (Mayo Clinic). Placebo-controlled trials in adults 70 and older (AFFIRM: women only), started in 2018. Both are enrolling by invitation, with an estimated primary completion date of November 2026.
- Steadman Philippon Research Institute. An open-label trial in 82 adults 55 and older comparing 100 mg daily with two-day high-dose courses. Completed in January 2024.
- Fisetin LOW (Copenhagen). 100 mg a day or placebo for 7 weeks in adults 50 and older, measuring suPAR, a blood marker of inflammation, and side effects. Recruiting.
- A dropped group. A Mayo Clinic bone-marker trial in older women planned a fisetin group but discontinued it because of the COVID pandemic and cost.
How to read a fisetin label
- Find the milligrams of fisetin itself. "Fisetin 200 mg" is the dose. "Extract 500 mg (40% fisetin)" needs math: that is 200 mg.
- Tell a purity spec from a product test. "98% purity" usually describes the raw powder the maker bought. A finished-product assay measures the fisetin in the capsule you swallow. Ask for both.
- Match the certificate to your bottle. The certificate of analysis should carry the same lot number as your bottle.
- Check who tested it. Look for a lab accredited to ISO/IEC 17025 that is separate from the seller.
- Skip hidden blends. A "proprietary blend" hides how much fisetin is inside. A multi-ingredient formula should list every amount.
- Compare the dose to the evidence. The published daily studies used 200 to 800 mg a day. A bigger number on a label is not backed by more human data.
Questions readers ask
- Does fisetin work?
- In people, nobody knows yet. In one 12-week trial in men with obesity, some blood markers of inflammation fell with 200 mg a day, but the main marker changed only with exercise. A trial in veterans found no benefit over placebo. The lifespan results come from mice.
- Has fisetin been tested in humans?
- Only in small studies: four with published results, and fewer than 100 people took fisetin in them. A 2026 review counted 34 registered fisetin trials; 4 had results.
- How much fisetin per day did studies use?
- Published daily studies used 200 to 800 mg; two registered trials are testing 100 mg. The 12-week trial used 200 mg. The Mayo Clinic trials use about 20 mg per kg of body weight for two days in a row. No study has worked out an ideal dose.
- What are the side effects of fisetin?
- Three studies reported no adverse events. In the veterans' trial, two of 11 men reported more fatigue on 800 mg a day. A lab study suggests fisetin may affect a liver enzyme that clears some medicines, so ask your doctor or pharmacist if you take prescription drugs.
- Should fisetin be taken with food?
- Nobody knows yet. No published human study has compared fisetin with and without food; a registered German study, FISEKIN-1, is set up to test it.
- Does fisetin slow aging?
- No human study has shown that. Old mice given fisetin lived longer. In a 10-person pilot, a blood test of biological age went down in 4 people and up in 5.
- Can I get fisetin from food?
- Fisetin occurs in strawberries, apples, persimmons, grapes, onions and cucumbers. We did not find a human study comparing the amounts in food with supplement doses.
See Prime Fisetin
The studies above were not conducted on BoneScience products. Prime Fisetin combines fisetin with other ingredients, and the finished product has not been tested in a clinical trial.
Related: Does NMN Work? What 12 Human Studies Actually Found · Black Ginger: What 10 Human Trials Actually Found
Sources
- Alipour M, et al. J Int Soc Sports Nutr. 2026;23(1):2679718. PubMed · doi
- Alipour M, et al. Nutrients. 2026;18(3):433. PubMed · doi
- Krishnakumar IM, et al. J Nutr Sci. 2022;11:e74. PubMed · doi
- Hodgin KS, et al. Int J Environ Res Public Health. 2021;18(5):2483. PubMed · doi
- Lee E, Burns M. Altern Ther Health Med. 2024;30(9):6-10. PubMed
- Sandoval-Caballero C, et al. Nutrients. 2026;18(18):2999. PubMed · doi
- Tavenier J, et al. Basic Clin Pharmacol Toxicol. 2026;139(3):e70290. PubMed · doi
- Yousefzadeh MJ, et al. EBioMedicine. 2018;36:18-28. PubMed · doi
- Shrestha R, et al. Drug Metab Pharmacokinet. 2018;33(2):111-117. PubMed · doi
- Khan N, et al. Antioxid Redox Signal. 2013;19(2):151-162. PubMed · doi
- Farr JN, et al. Nat Med. 2024;30(9):2605-2612. PubMed · doi
- ClinicalTrials.gov: AFFIRM NCT03430037 · AFFIRM-LITE NCT03675724 · NCT07918261 · Fisetin LOW NCT07195318 · FISEKIN-1 NCT06796374 · NCT04313634. Accessed November 8, 2026.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for general education and is not medical advice.