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| Chellian J et al 2025 · Research Square | animal | mixed | low | Chronic animal (rat) preprint, not peer-reviewed: STZ-induced type-1-diabetic rats given quercetin 10 mg/kg/day, metformin 180 mg/kg/day, or the combination for 30 days.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 et al 2026 · study_type: animal | 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 et al 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 et al 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 et al 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 et al 2025 · study_type: animal | 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 et al 2025 · study_type: RCT | 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 et al 2026 · study_type: animal | 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. |
Disagree, or know a study we missed?
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.