Definition Of Bioflavonoids

Bioflavonoids consist of thousands of antioxidant plant compounds. Bioflavonoids are also known simply as flavonoids, since all flavonoids are plant-based. These compounds occur in many of the foods you eat, including fruits, vegetables, soy products, wine, nuts, spices and teas. Research has indicated that bioflavonoids might provide protection against cardiovascular disease and some forms of cancer.

Structure

Bioflavonoids are polyphenolic compounds that share a common structure of phenylchromane, or phenyl-1,4-benzopyrone. These compounds are further broken down into subclasses including anthocyanidins, isoflavones, flavanols, flavanones, flavones and flavonols. The most common bioflavonoids found in plants are the flavonols and one subtype of flavanol called catechins. In the typical human diet, flavanols are the most common subclass of bioflavonoid.

Subclasses

Anthocyanidins are antioxidant bioflavonoids that create the deep color found in many fruits, such as blueberries, red grapes and raspberries. Isoflavones are bioflavonoids found in soy products and include daidzein, genistein and glycitein. Isoflavones are more common in Asian diets than North American diets because of the consumption of soy in countries such as China and Japan. Flavones include luteolin and apigenin and occur in hot peppers, thyme and parsley. Flavanones are found in citrus fruits and include hesperetin, eriodictyol and naringenin. Flavanols include catechins and proanthocyanidins, which occur in green and black tea, grapes and chocolate. Flavonols are widely found in most fruits and vegetables. In the human diet, the most common type of flavonol is quercetin.

Quercetin

Quercetin is a flavonol and the most common bioflavonoid in the human diet. It occurs in different amounts in all plants, with the highest amounts in apples, grapes, red wine, berries, tea, broccoli and onions. Dietary supplements also contain quercetin. Quercetin is not only a potent antioxidant, it is also biologically active. It inhibits a number of enzymes and is capable of changing the function of cells. Extensive scientific studies have examined the role of quercetin in inhibiting inflammation and reducing the risk of high blood pressure, cardiovascular disease and diabetes.

Metabolism

Bioflavonoids are present in food as glycosides, molecules bound to sugar groups. In this form, they are resistant to the heat from cooking, methods of processing and to destruction by stomach acid. Flavonoids are absorbed in your small intestine, where they can remain as glycosides or the sugar group is removed, making them aglycones. Bacteria in the colon can further change the bioflavonoid by hydrolyzing it, causing the molecule to react with water. Once bioflavonoids leave the bowel, the liver further transforms these molecules. With all of these biochemical changes, very little of the bioflavonoid's original glycoside form can be detected in your blood. The target of current research is examining the further metabolism of bioflavonoids once they reach target cells in your body.