Quercetin was discovered by J. Rigaud in 1854. It is a water-soluble natural pigment found in plant foods. It is the most abundant flavonoid and the most common in human nutrition, standing out for its high antioxidant activity. Many plants, whether considered medicinal or not, owe much of their benefits to the high levels of quercetin they present. For example, some kinds of onion, such as red, contain so much quercetin that the compound represents 10% of their dry density. It has been shown in experimental studies to have numerous effects on the body, including the inhibition of both the production and release of histamine, being especially best known for its antioxidant action. There are recent studies that demonstrate its contribution to cardiovascular well-being. Quercetin is found in many fruits. In the United Kingdom it is also apples (in addition to onions) that, through the diet, provide it in the greatest quantity. Each 500mg tablet provides significantly more Quercetin than 1kg of apples.
