In 1937, Albert Szent-Gyorgyi received a Nobel Prize for discovering vitamin C and
flavonoids, as well as for exploring their biochemical properties. Originally, he gave the
flavonoids the name "vitamin P" because of their effectiveness in reducing the permeability
of blood vessels. This name was abandoned when it was realized that these substances were not
really vitamins.
Quercetin is extracted from a variety of plant sources, including the onion peel and the
seeds and pods of Dimorphandra mollis, a legume tree native to South America.
Although we are far from knowing everything about quercetin, its antioxidant,
anti-inflammatory, and antihistamine (antiallergic) properties have been observed in numerous
in vitro and animal studies.