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, McAnulty LS, Nieman DC, Quindry JC, Hosick PA, Hudson MH, Still L, Henson DA, Milne GL, Morrow JD, Dumke CL, Utter AC, Triplett NT, Dibarnardi A 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, Tao T, Yao H, Zheng H, Wang F, Gao Y 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, Alimohammadi-Kamalabadi M, Hasani M, Malekahmadi M, Persad E, Heshmati J 2023 · Food science & nutrition | 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, Sekar R, Alzahrani A, Balasubramanian R, A Ahmed E, Behket GM, Ben Ammar R, Keddal Govindaram L 2026 · Toxicon : official journal of the International Society on Toxinology | 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, Hester GM, Alesi MG, Buresh RJ, Feito Y, Mermier CM, Ducharme JB, VanDusseldorp TA 2025 · Journal of bone and mineral metabolism | 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, Mazloom Z, Sherafatmanesh S, Ghorbani M, Firoozi D 2017 · European journal of clinical nutrition | 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, 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 | 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, Zheng Z, Zhao Y, Lin W 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, Henson DA, Maxwell KR, Williams AS, McAnulty SR, Jin F, Shanely RA, Lines TC 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, Tamtaji OR, Mirhosseini N, Lankarani KB, Akbari M, Heydari ST, Dadgostar E, Asemi Z 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, Jin S, Zhou T, Sheng G, Gao P, Li G 2025 · Food science & nutrition | 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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