Condition
    Moderate Evidence
    Effectiveness 3/5

    Quercetin for Chronic Inflammation

    Quercetin lowers CRP in meta-analysis, particularly at doses above 500mg daily and in people with elevated baseline inflammation. Bioavailability is poor and translation of biomarker change into clinical benefit is unproven.

    Overview

    Quercetin lowers CRP in meta-analysis, particularly at doses above 500mg daily and in people with elevated baseline inflammation. Bioavailability is poor and translation of biomarker change into clinical benefit is unproven.

    Verdict

    Mixed evidence

    How It Works

    Quercetin inhibits NF-kB activation, the master transcriptional switch for pro-inflammatory cytokines including TNF-alpha, IL-1beta and IL-6. It also stabilises mast cells, reducing histamine release, and scavenges reactive oxygen species directly. The practical constraint is pharmacokinetic. Free quercetin aglycone is poorly absorbed and rapidly conjugated in the intestine and liver, so plasma concentrations after oral dosing are typically far below those used in cell culture experiments. Phytosome and enzymatically modified isoquercitrin formulations improve exposure substantially.

    Dosing & Protocol

    Typical dose

    Recommended dose
    500-1000mg daily in divided doses
    Expected timeframe
    8-12 weeks

    Protocol

    form
    Quercetin phytosome or quercetin with bromelain/vitamin C for absorption
    duration
    8-12 weeks with CRP measured at baseline and end
    co factor
    Take with a fat-containing meal. Evidence is mixed: meta-analyses show quercetin lowers CRP modestly, with the effect concentrated in trials using at least 500 mg/day for more than eight weeks and in people with elevated baseline CRP; studies in healthy people with normal markers show nothing.
    titration
    Up to 1000-1500 mg/day in divided doses, as used in trials
    starting dose
    500 mg quercetin twice daily with food

    Evidence

    What the studies say

    A meta-analysis of randomised trials found that quercetin supplementation significantly reduced circulating CRP, with subgroup analyses indicating stronger effects at doses above 500mg daily, durations beyond eight weeks, and in participants with elevated baseline CRP. Effects on TNF-alpha and IL-6 were smaller and less consistent. No trial has demonstrated that this biomarker change translates into reduced disease activity or clinical events. Trials are mostly small, use varied formulations with very different bioavailability, and rarely last beyond three months. Quercetin can inhibit CYP3A4 and P-glycoprotein, so interaction with medications metabolised by those routes is a genuine consideration.

    Impact of quercetin on systemic levels of inflammation: a meta-analysis of randomised controlled human trials

    Score: 7/10
    2020
    meta_analysis

    Ou Q, Zheng Z, Zhao Y +1 more

    No relevant overall effects on peripheral CRP, IL-6 and TNF-alpha were observed

    View source

    Effects of supplementation with quercetin on plasma C-reactive protein concentrations: a systematic review and meta-analysis of randomized controlled trials

    Score: 8/10
    2017
    meta_analysis

    Mohammadi-Sartang M, Mazloom Z, Sherafatmanesh S +2 more

    The meta-analysis of seven RCTs (10 treatment arms) showed a significant reduction of circulating CRP levels (WMD: -0.33 mg/l)

    View source

    The Effect of Quercetin on Inflammatory Factors and Clinical Symptoms in Women with Rheumatoid Arthritis: A Double-Blind, Randomized Controlled Trial

    Score: 7/10
    2017
    rct
    n=50

    Javadi F, Ahmadzadeh A, Eghtesadi S +2 more

    Quercetin supplementation for 8 weeks significantly reduced EMS, morning pain, and after-activity pain

    View source

    Safety

    Caveats

    Inflammation is a marker, not a diagnosis - persistently raised CRP needs a cause identified, since infection, autoimmune disease and malignancy all raise it. Do not use quercetin in place of disease-modifying treatment for rheumatoid arthritis or IBD. Safety ceiling: doses above 1000-1500 mg/day lack long-term data, and high-dose intravenous quercetin has caused renal injury. Quercetin inhibits CYP3A4 and P-glycoprotein, raising levels of ciclosporin, some statins, warfarin, and certain chemotherapy agents. Avoid in pregnancy and breastfeeding.

    Less likely to help if

    People with normal baseline CRP, in whom trials show no measurable change.

    Medical Disclaimer

    The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.

    Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.