Bioflavonoids (or flavonoids) are a class of water-soluble plant pigments that bring color to many fruits and vegetables. Citrus fruits are a rich source of bioflavonoids, including disomin, hesperidin, rutin, and naringenin. Flavonoids are broken down into categories. One system breaks flavonoids into isoflavones, anthocyanidins, flavans, flavonols, flavones, and flavanones. Although they are all structurally related, their functions are different.
Citrus bioflavonoids and related substances are widely used in Europe to treat diseases of the blood vessels and lymph system, including hemorrhoids, chronic venous insufficiency, easy bruising, nosebleeds, and lymphedema following breast cancer surgery. These compounds are thought to work by strengthening the walls of blood.
While they are not considered essential, some flavonoids act as anti-inflammatory, antihistaminic, and antiviral agents. Quercetin can block the “sorbitol pathway” that is linked to many problems associated with diabetes. Rutin and several other flavonoids may also protect blood vessels and act as antioxidants, protecting LDL-cholesterol from oxidative damage, a goal for anyone with concerns about developing heart disease.
Others, such as the anthocyanidins from bilberry, may help protect the lens of the eye from cataracts. Animal research suggests that naringenin may have anticancer activity while soy isoflavones are also currently being studied to see if they help fight cancer.