GNC Quercetin 500mg: Fight Free Radicals In Your Body*. Antioxidants can help protect against harmful free radicals that can destroy healthy cells and promote the cell aging process*. Some free radicals may be produced by intense exercise—so if you're starting a new workout program, you might want to consider a daily quercetin supplement. Quercetin Has Antioxidant Properties. Antioxidants help to control cell-damaging free radicals by becoming oxidized themselves*. Just one daily serving of GNC Quercetin delivers 500mg of a bioflavonoid with antioxidant properties. Trust Science-Backed Support. Whether you're building a new training regimen or taking a look at new ways to support wellness, find out how the benefits of GNC Quercetin 500mg can help you achieve your goals. A bioflavonoid with antioxidant properties* Contains 60 caplets These statements have not been evaluated by the Food & Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.