QUERCETIN

Quercetin is the most abundant of the flavonoids. Quercetin belongs to the flavonoids family and consist of 3 rings and 5 hydroxyl groups. Querctin is also a building block for other flavonoids. Quercetin occurs in food as a aglycone (attached to a sugar molecule). Only a small percentage of the ingested quercetin will get absorbed in the blood.

Distribution

Quercetin is found in many common foods including apple, tea, onion, nuts, berries, cauliflower and cabbage.

Health Benefits of Quercetin

Quercetin, a member of the flavonoids family, exerts many beneficial health effects, including improvement of cardiovascular health, reducing risk for cancer, protection against osteoporosis. This phytochemical has anti-inflammatory, anti-allergic and antitoxic effects. Most of these properties are linked to its strong antioxidant action of quercetin but quercetin also modulates the expression of specific enzymes. Quercetin induces apoptosis and influences protein and lipid kinase signaling pathways. Quercetin is a candidate for preventing obesity-related diseases.

Diabetes

Quercetin may help to reduce symptoms of diabetes patients. One study showed that quercetin reduced blood glucose level and improved improved plasma insulin levels in streptozotocin-induced diabetic rats. An in-vitro study concluded that quercetin may have a pharmacological application in treating cardiovascular disease in diabetes mellitus patients.
Anti-inflammatory

Quercetin shows anti-inflammatory action by its direct antioxidant action and inhibition of inflammatory mediators and enzymes, such as lipoxygenase. Quercetin also inhibits the release of histamine, which causes congestion, by basophils and mast cells. Studies have shown an improved lung function and lower risk of certain respiratory diseases (asthma and bronchitis) for people with high apple (rich in quercetin) intake. Patients with increased levels of inflammation and oxidative stress might benefit most from a quercetin supplementation.
Heart disease

Studies demonstrate that flavonoid-rich diets protect against myocardial infarction and stroke. As many other flavonoids, quercetin inhibits oxidation of LDL (bad) cholesterol, lowers blood pressure and reduces the risk of heart disease.
Anti-cancer

Studies have shown that quercetin reduces cancer risk of prostate, ovary, breast, gastric and colon cells. Numerous in-vitro studies show that quercetin induces apoptosis of cancer cells through different mechanisms.
Performance

Quercetin supplementation has been linked with improved performance, but supporting evidence is week and often conflicting. Scientists suggest that quercetin may aid performance through its anti-inflammatory properties or by stimulating the activity of mitochondria.

Research Reviews

Dietary Intakes of Flavonols, Flavones and Isoflavones by Japanese Women and the Inverse Correlation between Quercetin Intake and Plasma LDL Cholesterol Concentration

Tissue Distribution of Quercetin in Rats and Pigs

The Effect of Quercetin on SW480 Human Colon Carcinoma Cells: a Proteomic Study

Quercetin inhibits eNOS, microtubule polymerization, and mitotic progression in bovine aortic endothelial cells.

Rat Gastrointestinal Tissues Metabolize Quercetin