Supplements · Metabolic & Cardiometabolic
quercetin improves endothelial function
In plain terms: Does quercetin improve blood-vessel function?
Part of: 🧪 quercetin
Unknown, honestly. Nobody has run the standard blood-flow test in people taking quercetin. The one human study measured artery segments removed during heart surgery, and it worked in men and did nothing in women.
📅 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: Animal studies (Animal)
How the studies fall
What the evidence shows
Still no clean human trial. Across two sweeps, not one study measured brachial flow-mediated dilation — the standard endothelial-function endpoint — in humans given quercetin alone.
The evidence (8)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Chellian J et al 2025 · Research Square | animal | mixed | low | Chronic animal (rat) preprint, not peer-reviewed: STZ-induced type-1-diabetic rats given quercetin 10 mg/kg/day, metformin 180 mg/kg/day, or the combination for 30 days. Quercetin alone partially restored vascular/endothelial function (incr TEMPERED: reports molecular surrogates (eNOS/VCAM-1/plaque) rather than a functional endothelium-dependent vasodilation measurement. |
| Mori A, Sakurai A, Takimoto S, Sakamoto K, Nakahara T 2026 · International journal of molecular sciences | animal | supports | moderate | Acute animal (rat) study: intravenous quercetin (10-100 µg/kg/min) dose-dependently increased retinal arteriolar diameter; dilation was abolished by intravitreal L-NAME (NO-synthase inhibitor), confirming an NO-dependent mechanism, with no |
| Lv Y, Weng X, Zhu Y, Zhang X, Ma Y, Dai X, Bai X, Zhang S, Qi J, Zhu X, Chen Y, Zeng M, Meng W, Wu Q, Li J, Jia H, Yu B 2026 · British journal of pharmacology | animal | mixed | low | OVX + high-fat-diet ApoE-/- mouse (postmenopausal atherosclerosis, chronic) + ox-LDL-HUVEC: quercetin suppressed endothelial ferroptosis (raised GPX4, lowered ACSL4/ROS/iron) via KEAP1 ubiquitination -> NRF2 activation; effect lost with NRF TEMPERED: reports molecular surrogates (eNOS/VCAM-1/plaque) rather than a functional endothelium-dependent vasodilation measurement. |
| Long HJ, Liu QJ, Qin SY, Xiang H, Ouyang J, Liao JX, Tao Y, Huang JQ, Chen SH, Lu HW 2026 · The American journal of Chinese medicine | animal | mixed | low | ApoE mouse (high-fat diet, chronic) + ox-LDL-HUVEC model: quercetin reduced aortic plaque/necrotic core and restored endothelial barrier integrity/reduced monocyte adhesion by suppressing ox-LDL-induced ferroptosis via the PACS2-HMOX1 pathw TEMPERED: reports molecular surrogates (eNOS/VCAM-1/plaque) rather than a functional endothelium-dependent vasodilation measurement. |
| Baghdadi MA, do Carmo Las Casas PHF, Mbemba E, Rousseau A, Kempaiah P, Svistunov AA, Bitsadze V, Sabbah M, Fareed J, Van Dreden P, Trachana V, Lefkou E, Gerotziafas G 2026 · Cancers | in-vitro | mixed | low | HUVECs pretreated with quercetin before exposure to pancreatic/breast-cancer-derived extracellular vesicles: quercetin gave only a 'partial and limited protective effect' on endothelial dysfunction (vs. no protection from LMWH/apixaban). No TEMPERED: reports molecular surrogates (eNOS/VCAM-1/plaque) rather than a functional endothelium-dependent vasodilation measurement. |
| Mkhize SA, Nthlane RA, Xhakaza SP, Verhaert PD, Baijnath S, Millen AME, Michel FS 2025 · Basic & clinical pharmacology & toxicology | animal | supports | low | ACUTE single IV dose quercetin (4.5 mg/kg) in L-NAME-induced hypertensive female SD rats: produced concentration-dependent vasodilation in isolated mesenteric arteries and increased sensitivity to ACh-induced (endothelium-dependent) relaxat |
| Mury P, Dagher O, Fortier A, Diaz A, Lamarche Y, Noly PE, Ibrahim M, Pagé P, Demers P, Bouchard D, Bernier PL, Poirier N, Moss E, Durrleman N, Jeanmart H, Pellerin M, Lettre G, Thorin-Trescases N, Carrier M, Thorin E 2025 · Aging cell | RCT | mixed | moderate | RCT, 97 CAD patients (78 men) undergoing CABG; short-term/chronic dosing (quercetin 500 mg twice daily vs placebo, n=47 vs 50, for ~2 days pre-op through hospital discharge). Ex-vivo endothelial acetylcholine-induced relaxation of internal |
| Liu H, Yan H, Yao Y, Yu D, Wang C, Liu Y, Wang C 2026 · European journal of medical research | animal | mixed | low | Radiation-induced erectile-dysfunction rat model (20 Gy pelvic irradiation), CHRONIC 28-day oral quercetin at 10 or 40 mg/kg/day (n=8/group): partially restored endothelial marker CD31/eNOS expression and NO/cGMP signaling alongside erectil TEMPERED: reports molecular surrogates (eNOS/VCAM-1/plaque) rather than a functional endothelium-dependent vasodilation measurement. |
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