Supplements
quercetin decreases C-reactive protein
In plain terms: Does quercetin reduce inflammation, as measured by CRP?
Part of: 🧪 quercetin
The reviews contradict each other, and the cleanest individual trials found nothing. Any real effect looks limited to people who are already inflamed, at 500 mg a day or more, not healthy people hoping to lower a normal reading.
📅 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)
How the studies fall
What the evidence shows
The human syntheses disagree with each other. One meta-analysis of 16 RCTs in metabolic-syndrome patients found a significant CRP drop (SMD -0.64) but with extreme heterogeneity (I2 = 90%); another found no overall effect, with a signal appearing only in a "diagnosed disease" subgroup.
The evidence (12)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Hellal D et al 2026 · Research Square | animal | supports | low | Unreviewed preprint; rat Freund's-adjuvant RA model, n=24 (4 groups of 6). Quercetin decreased serum CRP and rheumatoid factor alongside IL-1beta/TNF-alpha and mTOR/p-AKT expression vs arthritic controls, comparably to rapamycin. |
| McAnulty SR et al 2008 · Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme | RCT | contradicts | moderate | RCT in 40 athletes, 1000mg/day quercetin vs placebo for 6 weeks plus 3 days of cycling: CRP rose significantly with exercise in both groups with no treatment effect — a clean null despite quercetin's in-vitro antioxidant activity. |
| Liu X et al 2023 · Inflammopharmacology | animal | supports | low | Meta-analysis of 17 animal RA studies (n=251 animals) found quercetin reduced CRP along with IL-1β, IL-6, IL-17, TNF-α, MCP-1, MDA and NF-kB vs control. Preclinical only (SYRCLE risk-of-bias concerns); authors call for more high-quality stu |
| Ziaei S et al 2023 · study_type: meta-analysis | meta-analysis | contradicts | moderate | Meta-analysis of 5 RCTs, n=544 COVID-19 patients; quercetin reduced LDH (SMD -0.42), hospital admission (RR 0.30), ICU admission (RR 0.27), and mortality (RR 0.18), but no significant change in CRP, D-dimer, or ferritin between groups. |
| Rajendran P et al 2026 · study_type: animal | animal | supports | low | Mouse silica-induced lung injury model; a prenylated quercetin derivative (SA, not pure quercetin) at 50-100 mg/kg every 2 days x6 weeks dose-dependently reduced serum CRP, TNF-alpha, IL-1beta, and IL-6 vs SiO2-only controls. |
| Bailly AR et al 2025 · study_type: RCT | RCT | contradicts | low | Double-blind RCT, n=33 postmenopausal women, 500 mg/day quercetin x90 days; IL-6 (p=0.045) and TNF-alpha (p=0.021) decreased vs placebo, but CRP was unchanged (p=0.448, d=0.34). |
| Mohammadi-Sartang M et al 2017 · study_type: meta-analysis | meta-analysis | supports | moderate | Meta-analysis of 7 RCTs/10 treatment arms; overall WMD -0.33 mg/L (95% CI -0.50 to -0.15, P<0.001). Larger effect at doses >=500 mg/day (WMD -0.34, 95% CI -0.52 to -0.16) and in subjects with baseline CRP <3 mg/L (WMD -0.34, 95% CI -0.51 to |
| Mury P et al 2025 · study_type: RCT | RCT | contradicts | moderate | Double-blind RCT, 97 CABG patients (500 mg BID quercetin pre-op through discharge); only a non-significant trend toward reduced CRP at discharge (p=0.073). Effect was sex-differential: endothelial/inflammatory benefit in men only, pro-infla |
| Ou Q et al 2020 · International journal of food sciences and nutrition | meta-analysis | contradicts | moderate | Meta-analysis of RCTs (6 studies pooled for CRP) found NO significant overall effect of quercetin on circulating CRP (or IL-6, TNF-α). Subgroup-only signal: significant CRP reduction in participants with diagnosed disease (SMD=-0.24, 95% CI |
| Nieman DC et al 2009 · Medicine and science in sports and exercise | RCT | mixed | low | RCT in 39 trained cyclists (placebo vs quercetin 1000mg vs quercetin+EGCG+isoquercetin+EPA/DHA) after 3 days heavy exertion: CRP significantly decreased in the multi-compound Q-EGCG combination arm vs placebo, but no significant isolated qu |
| Tabrizi R et al 2020 · Critical reviews in food science and nutrition | meta-analysis | supports | moderate | Meta-analysis of 16 RCTs in metabolic-syndrome/related-disorder patients: quercetin significantly decreased CRP (SMD=-0.64, 95% CI -1.03 to -0.25, p=0.001, I2=90.2%) plus total-cholesterol and LDL-C, but not TG, HDL-C, IL-6 or TNF-α. High h |
| Jin D et al 2025 · study_type: meta-analysis | meta-analysis | supports | moderate | Meta-analysis of 7 RCTs, 540 MASLD patients; quercetin significantly reduced liver enzymes (ALT/AST/GGT), direct bilirubin, and CRP, plus improved lipids. No significant effect on TNF-alpha, kidney function, or BMI. GRADE certainty very low |
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