Some scientists believe that naturally occurring bioflavinoids increase the influence of ascorbic acid on good health. Flavinoids are, in essence, plant pigments largely responsible for the colors of many fruits and vegetables that often contain large quantities of vitamin C. Over 4,000 flavinoid-type compounds have been identified and classified according to chemical structure. Some of the better-established citrus flavinoids include rutin, hesperidin, and quercitin, which function to increase capillary permeability. The scientist who discovered both vitamin C and the first flavinoids, Dr. Albert Szent-Gyorgyi, received a Nobel Prize for his research relating to these substances.