Supplements
quercetin decreases cancer risk
In plain terms: Does quercetin prevent cancer?
Contested Supplements 🔬 Includes disconfirming
Part of: 🧪 quercetin
RefutedContestedStrong support
consensus score 0.18
The evidence is scattered and site-by-site: a repeated hint for lung cancer, a clean null for ovarian, and for prostate the biggest analysis found MORE cancer, not less. None of it can separate quercetin from the fruit and vegetables that contain it.
📅 Last reviewed: 2026-07-26 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
MechanismIn-vitroAnimalObservationalRCTMeta-analysis
How the studies fall
5 support 3 contradict 0 tested null 9 mixed · 17 sources, 7 independent groups
What the evidence shows
Loud evidence and relevant evidence are two different literatures here. The overwhelming majority of "quercetin anticancer" work is cell-line and rodent research that carries no implication for human risk. The human evidence is dietary-flavonol epidemiology, and it is scattered and site-inconsistent: the most repeated inverse association is lung cancer (OR ~0.66-0.
The evidence (21)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Xie Y, Huang S, Su Y 2016 · Nutrients | meta-analysis | mixed | moderate | Meta-analysis of 12 human population studies (4,593 cases, 519,378 controls) found dietary flavonol intake associated with reduced gastric cancer risk (OR 0.80, 95% CI 0.70-0.91) but no significant association with esophageal cancer (OR 0.8 |
| Amjadi A, Abbasi H, Tahavorgar A, Esfahanian M, Torkaman M, Shahrokhi Sardoo A, Erfanimanesh A, Shamsi-Goushki A, Akbari ME, Alhouei B, Gholamalizadeh M, Doaei S 2026 · Expert reviews in molecular medicine | meta-analysis | supports | moderate | Umbrella review re-pooling meta-analyses (units are syntheses, rubric #690): 'Eligible studies included meta-analyses that examined polyphenol intake and DSC risk.' 'Data from six meta-analyses, encompassing 27 effect sizes, revealed a statistically significant 11% reduction in the risk of DSCs' (RR 0.89, 0.85-0.93); quercetin subgroup 22% lower, digestive cancers only. Review — zero weight. |
| Zamora-Ros R, Sacerdote C, Ricceri F, Weiderpass E, Roswall N, Buckland G, St-Jules DE, Overvad K, Kyrø C, Fagherazzi G, Kvaskoff M, Severi G, Chang-Claude J, Kaaks R, Nöthlings U, Trichopoulou A, Naska A, Trichopoulos D, Palli D, Grioni S, Mattiello A, Tumino R, Gram IT, Engeset D, Huerta JM, Molina-Montes E, Argüelles M, Amiano P, Ardanaz E, Ericson U, Lindkvist B, Nilsson LM, Kiemeney LA, Ros M, Bueno-de-Mesquita HB, Peeters PH, Khaw KT, Wareham NJ, Knaze V, Romieu I, Scalbert A, Brennan P, Wark P, Vineis P, Riboli E, González CA 2014 · British journal of cancer | observational | supports | moderate | EPIC cohort (477,312 participants across 10 European countries, 1,575 incident bladder cancer cases, ~11y follow-up) found dietary flavonol intake inversely associated with bladder cancer risk (HR 0.74, 95% CI 0.61-0.91, top vs. bottom quin |
| Zhou Y, Gu K, Zhou F 2023 · Nutrients | observational | supports | low | NHANES population-based cohort (14,029 participants, 405 cancer deaths over ~117 months) found dietary flavonol intake inversely associated with all-cause cancer mortality across quartiles vs. lowest (HR ~0.54-0.58, p=0.02-0.05), with effec |
| Duan X, Zhang L, Liu F 2025 · Frontiers in pharmacology | animal | mixed | low | Meta-analysis of preclinical animal studies found quercetin treatment reduced tumor/precancerous lesion markers and cell proliferation (PCNA SMD -8.22) in rodent colorectal-cancer models. The authors themselves note human clinical research TEMPERED: preclinical (cell-line/animal) work — carries no implication for human cancer RISK, which is what this claim asserts. |
| Kubina R, Iriti M, Kabała-Dzik A 2021 · Nutrients | in-vitro | mixed | low | Systematic review of PRECLINICAL (in-vitro/animal) studies only, on quercetin/fisetin/kaempferol's antiproliferative and proapoptotic activity in head & neck cancer cell lines and signaling pathways. No human dietary-intake or risk data pre TEMPERED: preclinical (cell-line/animal) work — carries no implication for human cancer RISK, which is what this claim asserts. |
| Chang H, Lei L, Zhou Y, Ye F, Zhao G 2018 · Nutrients | meta-analysis | supports | moderate | Meta-analysis of 12 studies (5 cohort, 7 case-control; 17,481 cases/740,859 controls): highest vs lowest flavonol intake (class including quercetin) OR=0.70 (0.54-0.90) for colon cancer, but no significant effect on rectal cancer (OR=0.93 |
| Yi G, Liu Y, Li G, Chang K 2026 · Molecules | in-vitro | mixed | low | Narrative review: 'This narrative review was conceptualized with reference to the Scale for the Assessment of Narrative Review Articles (SANRA) guidelines'. Content is preclinical: quercetin 'exhibits pleiotropic anti-cancer activities in preclinical models'; no human risk data. Review — zero weight. |
| Rostampour K, Alipour K, Mirjalili F, Forootani B, Yekrang Safakar H, Beigrezaei S, Forbes SC, Salehi-Abargouei A 2025 · Nutrition and cancer | meta-analysis | supports | moderate | GRADE-assessed meta-analysis of 20 observational studies: quercetin intake OR=0.66 (95% CI 0.48-0.91, p=0.01) for lung cancer, alongside similar inverse signals for other flavonoid subclasses. Dietary-intake design cannot isolate quercetin |
| Huang Y, Wang W, Jin J 2024 · Frontiers in nutrition | meta-analysis | contradicts | moderate | Meta-analysis of 38 human observational studies (11 cohort, 27 case-control; n=824,933) found dietary flavonol intake associated with a small but statistically significant INCREASE in prostate cancer risk (OR 1.05, p=0.042), opposite to the |
| El-Mansy MN, Hamdy ZM, Abdelsamie AE, El-Borady OM 2026 · Nanoscale advances | animal | mixed | low | Hamster DMBA-induced oral carcinogenesis model: oral quercetin (25 mg/kg, 3x/week) reduced Ki-67/Bcl-2 expression and carcinoma severity versus DMBA-only controls. Animal chemoprevention model at pharmacologic dose, not a human dietary-inta TEMPERED: preclinical (cell-line/animal) work — carries no implication for human cancer RISK, which is what this claim asserts. |
| Wang K, Lu T, Yang R, Zhou S 2024 · Nutrients | observational | supports | low | NHANES cohort of 6,110 hypertensive US adults (43,977 person-years, 265 cancer deaths) found higher flavonol intake associated with lower cancer-related mortality (HR 0.52, 95% CI 0.28-0.96), while total-flavonoid intake alone showed no sig |
| Bandera EV, Williams MG, Sima C, Bayuga S, Pulick K, Wilcox H, Soslow R, Zauber AG, Olson SH 2009 · Cancer causes & control : CCC | observational | mixed | low | Case-control study (424 endometrial cancer cases, 398 controls): quercetin intake showed a borderline inverse association (OR=0.65, 95% CI 0.41-1.01, highest vs lowest quartile, p-trend=0.02). Confidence interval crosses the null; small cas |
| Gates MA, Vitonis AF, Tworoger SS, Rosner B, Titus-Ernstoff L, Hankinson SE, Cramer DW 2009 · International journal of cancer | observational | contradicts | moderate | Large case-control study (1,141 ovarian cancer cases, 1,183 controls) testing 5 individual flavonoids: quercetin intake showed no significant association with ovarian cancer risk; only apigenin showed a borderline inverse association (RR=0. |
| Li H, Zeng Y, Zi J, Hu Y, Ma G, Wang X, Shan S, Cheng G, Xiong J 2024 · Mol Nutr Food Res | meta-analysis | mixed | low | Umbrella review of syntheses: 'an umbrella review of meta-analyses and systematic reviews is conducted' (32 articles); exposures are total flavonoids and subclasses ('flavonol and gastric cancer'), no quercetin-specific estimate. Review — zero weight. |
| Simons CC, Hughes LA, Arts IC, Goldbohm RA, van den Brandt PA, Weijenberg MP 2009 · International journal of cancer | observational | contradicts | moderate | Netherlands Cohort Study (120,852 participants, ~2,485 colorectal cancer cases, 13.3y follow-up) found NO overall association between dietary flavonol, flavone, or catechin intake and colorectal cancer endpoints. A protective catechin (not |
| Shahid B, Sultan MT, Noman AM, Yehuala TF, Nafees I, Maaz M, Fatima A, Amjad A, Raza H 2026 · Discover oncology | in-vitro | mixed | low | Systematic review of 24 preclinical studies (16 in vitro cell-line, 8 in vivo animal) found quercetin/kaempferol reduced cancer cell viability and induced apoptosis in lung, breast, and colorectal models via PI3K/Akt, MAPK, NF-kB, and p53 p TEMPERED: preclinical (cell-line/animal) work — carries no implication for human cancer RISK, which is what this claim asserts. |
| Wang Z, Huang J, Huang D, An R, Tong G, Yuan W, Liao M, Zhong Q 2026 · PloS one | animal | mixed | low | In vitro HCC cell lines plus mouse xenograft model: quercetin dose-dependently suppressed EGFR/PI3K/AKT/GSK3β signaling and reduced HBV-associated hepatocellular carcinoma tumor growth. Preclinical mechanism/xenograft study at experimental TEMPERED: preclinical (cell-line/animal) work — carries no implication for human cancer RISK, which is what this claim asserts. |
| Woo HD, Kim J 2013 · PloS one | meta-analysis | mixed | moderate | Meta-analysis of 35 studies (19 case-control, 15 cohort; ~1M subjects total) found dietary quercetin (and kaempferol) intake significantly associated with decreased smoking-related cancer risk (aerodigestive tract/lung) only in smokers, wit |
| Parvaresh A, Razavi R, Rafie N, Ghiasvand R, Pourmasoumi M, Miraghajani M 2016 · Journal of research in medical sciences : the official journal of Isfahan University of Medical Sciences | observational | contradicts | low | Narrative systematic review (13 total studies: only 1 prospective + 2 case-control in humans, rest animal/in-vitro) concluded epidemiological data did NOT show quercetin significantly decreases ovarian cancer risk at typical dietary intake |
| Reale G, Russo GI, Di Mauro M, Regis F, Campisi D, Giudice AL, Marranzano M, Ragusa R, Castelli T, Cimino S, Morgia G 2018 · Complementary therapies in medicine | observational | mixed | low | Case-control study (118 prostate cancer cases, 222 controls, Sicily): high flavonol intake OR=0.19 (0.06-0.56) and catechin intake OR=0.12 (0.04-0.36) associated with reduced prostate cancer risk; flavanones were positively associated with TEMPERED: small (118-case) recall-bias-prone case-control whose protective prostate finding directly contradicts the far larger prostate meta-analysis; a genuine disagreement, not support. |
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