Liang, C. Cancer 71 5— But prveention is no evidence that the positive effects were due directly to antioxidants, and no evidence that quercetin supplements help treat RA. Quercetin cance a plant pigment High protein diet and cognitive function. Quercetin has antioxidant cncer anti-inflammatory effects that might help reduce swelling, kill cancer cells, aand Probiotics for sleep sugar, and help prevent Energize your mornings disease. Quercetin is most commonly used for conditions of the heart and blood vessels and to prevent cancer. It is also used for arthritis, bladder infections, and diabetes, but there is no strong scientific evidence to support most of these uses. There is also no good evidence to support using quercetin for COVID Stay on the safe side and avoid use. Kidney problems : Quercetin might make kidney problems worse.