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Quercetin

Quercetin: Quercetin is a part of the flavonoids. These are pigments – there over 4000 of them that give their colors to flowers, fruits and vegetables. These components which are naturally present in vegetables have numerous effects on the organism: The principal one is to reinforce the capillary walls (the smallest blood vessels) and to reduce their permeability. 

Quercetin and rutin are considered to be two of the most active flavonoids. It is the quercetin to which certain medicine plants, like the ginkgo and the St.John’s-wort, owe a part of their therapeutic effects. In supplements, it is often associated to vitamin C, which improves the absorption of quercetin by the organism and holds up its elimination.

Quercetin is extracted from diverse vegetable sources, notably from the onion peeling as well as from seeds and pods of the Dimophandra mollis, a tree from the legume family originating in South America. Even though we are far from knowing everything about quercetin, its antioxidant, anti-inflammatory and antihistamine properties have been observed during numerous in vitro and animal studies.

An epidemiological study in Finland linked a high consumption of foods which are rich in quercetin to a decrease of coronary heart problems and of strokes. Clinical studies also show that taking supplements of quercetin results in a decrease of the blood pressure for people with high blood pressure.

The endogenous quercetin content has been underestimated in the past and can be increased by the diet. Amongst the biological effects which have a particular interest, the effects of quercetin against human high blood pressure and the improvement of the endothelial function have to be underlined, as well as its anti-thrombotic and anti-inflammatory effects.

PMID: 18827577 [PubMed - listed for MEDLINE]