Flavonoid, << FLAY vuh noyd, >> is any of a number of chemicals made by plants. Flavonoids have many important roles in the life cycle of plants. For example, some flavonoids protect leaves from being damaged by ultraviolet light. Others provide the color of flowers, fruits, and leaves. Flavonoids may also provide ultraviolet markings in flower petals. These markings attract insect pollinators, such as bees, to the flowers.
Scientists have identified more than 4,000 naturally occurring flavonoids. Five main groups of these chemicals have been studied extensively by scientists: (1) anthocyanins, (2) flavanones, (3) flavones, (4) flavonols, and (5) isoflavones. A single plant does not make all of the flavonoids, only certain ones. Each plant species may produce a particular combination of the chemicals.
Because much of our food comes from plants, scientists are studying how the flavonoids in fruits and vegetables may affect human health and nutrition. Some flavonoids act as antioxidants, chemical compounds that may prevent some types of cell damage. These flavonoids may help protect against heart disease by preventing blood clots and keeping cholesterol from building up inside arteries. Another group of flavonoids act like the hormone estrogen and are used in hormone replacement therapy. The therapy restores estrogen after a woman’s ovaries stop producing the hormone at menopause. Scientists have also found that some flavonoids can prevent the formation of certain types of tumors. Since almost all fruits and vegetables contain beneficial flavonoids, experts recommend eating at least five servings every day.
See also Antioxidant ; Citrin ; Hormone replacement therapy .
