What Is It? Quercetin belongs to a class of water-soluble plant pigments called bioflavonoids that cannot be produced in the human body. It is also considered a phytoestrogen.* Uses For Quercetin Diminishes Histamine Release: Quercetin inhibits the synthesis of enzymes necessary for the release and degranulation of histamine. An in vitro study performed on neutrophils reported that quercetin mediated beta-glucuronidase and lysozyme release, as well as significantly moderated arachidonic acid release from cell membranes.* Antioxidant Support: Quercetin promotes cardiovascular health by protecting lipids from oxidation and supporting the health of capillaries by enhancing their strength and integrity. Studies suggest that quercetin may also promote healthy vision by mediating sorbitol production.* Cellular Support: An animal study indicated that quercetin supported prostate cell health by moderating receptor function at the transcription level. Additionally, in vitro studies have reported that this powerful flavonoid may be supportive of colon and breast cell health.*