A 2017 double blind, placebo controlled clinical trial tested the efficacy of quercetin on symptoms of rheumatoid arthritis in 50 women. Participants were randomized to receive 500 mg of quercetin or placebo daily for eight weeks. Blood work and clinical assessment, at the end of the study, revealed that patients treated with quercetin had significantly less early morning stiffness and pain and less after activity pain. The inflammatory marker TNF-a was also significantly reduced in the quercetin group compared to placebo.
Javadi F, Ahmadzadeh A, Eghtesadi S, Aryaeian N, Zabihiyeganeh M, Rahimi Foroushani A, Jazayeri S. The Effect of Quercetin on Inflammatory Factors and Clinical Symptoms in Women with Rheumatoid Arthritis: A Double-Blind, Randomized Controlled Trial. J Am Coll Nutr. 2017 Jan;36(1):9-15. doi: 10.1080/07315724.2016.1140093. Epub 2016 Oct 6. PMID: 27710596.