Quercetin

Quercetin is the most abundant of the flavonoids. Quercetin belongs to the flavonoids family. 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.

Sources

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

Properties

Quercetin 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. It is increasingly appearing as an additive to energy supplements.