Quercetin

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This section does not replicate the other information on this topic but provides additional details or context most relevant to professionals.

No effect of quercetin on EGCG bioavailability

Quercetin showed no evidence of an effect on bioavailability of EGCG and methylation activity in prostate tissue or red blood cells among men with prostate cancer treated with quercetin in a small RCT.¹Henning SM, Wang P et al. Prospective randomized trial evaluating blood and prostate tissue concentrations of green tea polyphenols and quercetin in men with prostate cancer. Food & Function. 2020 May 1;11(5):4114-4122.

Preclinical evidence

Notable preclinical evidence is presented here; clinical evidence is in How can quercetin help you? What the research says ›

Improving treatment outcomes

Quercetin increases chemosensitivity of cancer cells.²Hu Y, Li R, Jin J, Wang Y, Ma R. Quercetin improves pancreatic cancer chemo-sensitivity by regulating oxidative-inflammatory networks. Journal of Food Biochemistry. 2022 Dec;46(12):e14453; Zhang X, Huang J et al. Quercetin enhanced paclitaxel therapeutic effects towards PC-3 prostate cancer through ER stress induction and ROS production. OncoTargets and Therapy. 2020 Jan 16;13:513-523; Prieto-Vila M, Shimomura I et al. Quercetin Inhibits Lef1 and resensitizes docetaxel-resistant breast cancer cells. Molecules. 2020 Jun 1;25(11):2576. .

Managing side effects: preclinical evidence

Cardiotoxicity: Quercetin reduces the cardiotoxicity of doxorubicin combined with cyclophosphamide in cell studies.³Zhang P, Zhang J, Zhao L, Li S, Li K. Quercetin attenuates the cardiotoxicity of doxorubicin-cyclophosphamide regimen and potentiates its chemotherapeutic effect against triple-negative breast cancer. Phytotherapy Research. 2022 Jan;36(1):551-561. 

Immunosuppression and cognitive effects: Quercetin ameliorates cyclophosphamide-induced immunosuppression of rats.⁴Ebokaiwe AP, Ushang OR, Ogunwa TH, Kikiowo B, Olusanya O. Quercetin attenuates cyclophosphamide induced-immunosuppressive indoleamine 2,3-dioxygenase in the hippocampus and cerebral cortex of male Wister rats. Journal of Biochemical and Molecular Toxicology. 2022 Nov;36(11):e23179; Peter Ebokaiwe A, Olachi Obasi D, Kalu WO. Abatement of cyclophosphamide-induced splenic immunosuppressive indoleamine 2, 3-dioxygenase and altered hematological indices in Wister rats by dietary quercetin. Immunobiology. 2022 May;227(3):152218..

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