Quercetin is a flavonoid often found in dietary supplements used for treating various conditions. It seems to work as an antioxidant and may also have anti-inflammatory effects. The flavonoid may also inhibit the growth and division of certain cells (including cancer cells) and may have anti-estrogen effects. Some of the side effects that have been reported with this supplement include headaches and tingling of the extremities.
Quercetin is a flavonoid found in a variety of different plants and is claimed to provide several health benefits. Although it can be obtained through eating certain fruits and vegetables, it is also available in dietary supplements.
(Click Benefits of Quercetin for more information about possible uses of this product.)
Quercetin appears to have numerous different actions that could contribute to its medicinal activity. It seems to work as an antioxidant and may also have anti-inflammatory effects. It might inhibit the growth and division of certain cells, including cancer cells, and may have anti-estrogen effects (which could possibly contribute to some effect on hormone-related cancers, such as breast cancer). For allergies, it might work by inhibiting the release of histamine.
These are just a few ways that researchers have suggested that the substance may work for a variety of conditions. At this time, it is not fully known how the different activities of quercetin may work together (or even if the flavonoid really works for most uses).
Although research in laboratory animals or cells shows promise, there is not much evidence in humans to suggest that this flavonoid really works for most uses (see Does Quercetin Work? for more information).