Quercetin is actually an antioxidant that is found naturally in green tea, apples, citrus fruits, broccoli, onions, and other foods. Advocates of natural remedies are usually fans of quercetin, which may have antihistamine effects. It’s been linked to reduced inflammation. To take advantage of quercetin’s benefits, you can just add more quercetin-rich foods to your diet. You can also find quercetin dietary supplements in capsules and powders.