About this item Plant-Based Immune Support: Quercetin is a naturally occurring flavonoid found in certain fruits, vegetables, and herbs, such as red onions, leafy greens, apples, and red grapes. Quercetin 500 mg from Webber Naturals is a concentrated antioxidant supplement that helps support healthy respiratory, sinus, and immune system function.* Antioxidant Support: Quercetin is considered one of the most abundant flavonoids in the human diet. Despite its prevalence in common plant foods, flavonoid consumption varies widely from person to person, with the average intake estimated to be only 15 mg per day. Once-daily Quercetin 500 mg provides a convenient way to increase your quercetin intake.* Easy-to-Swallow: Convenient way to increase your flavonoid intake with an easy-to-swallow vegetarian capsule. Each capsule contains 500 mg of Quercetin. Free of: Artificial colors, preservatives, or sweeteners; no dairy, starch, sugar, wheat, gluten, yeast, soy, corn, egg, fish, shellfish, animal products, salt, tree nuts, or GMOs. Suitable for vegetarians and vegans