Source British Journal of Nutrition and NHI On Demand
Quercetin is one of a number of water-soluble plant pigments called bioflavonoids. Quercetin and the other bioflavonoids cannot be synthesized by humans. However, they reportedly exert a wide variety of biological effects when ingested. It has been shown to have anti-inflammatory and antioxidant properties, and is being investigated for a wide range of potential health benefits. Quercetin is found in many foods including apples, onions, tea, berries, grapes, broccoli, cauliflower, and cabbage, as well as many seeds and nuts.
A new study has found that increased intakes of the compound quercetin may reduce the risk of developing colon cancer by 50 percent. Researchers conducted a case-control study involving 264 people with confirmed colorectal cancer and 408 healthy, cancer-free controls. Using a food frequency questionnaire, researchers were able to calculate flavonoid intake. They determined that although no association was found between developing colorectal cancer and total daily flavonol intake, there was an inverse association between non-tea flavonol and colorectal cancer risk. When the researchers considered only flavonoids from non-tea sources and the specific site of the cancer, a significant protective effect was documented for non-tea flavonols, specifically, quercetin and colon cancer but there was no protective effect for rectal cancer. Therefore, the authors concluded that quercetin appears to reduce the risk of developing colon cancer.