Jarrow Formulas Quercetin supplement supports immune and cardiovascular health.(1) These quercetin 500 mg capsules support immune function by providing quercetin, the bioflavonoid antioxidant found in onions, green leafy vegetables, and fruits such as apples and cherries.(1) Quercetin supports healthy cellular function, cardiovascular health, and has been shown to support a healthy immune response.(1) This dietary supplement is non-GMO and is gluten-free. Adults take one capsule once a day with meals or as directed by your qualified healthcare professional. Jarrow Formulas – Superior Science. Smarter Formulas.(1)These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.