Supports Immune System. With Ascorbic Acid and Rutin. Citrus Bioflavonoids are powerful polyphenolic compounds found in lemons, limes, oranges, grapefruits, and tangerines. Bioflavonoids serve to protect cells from free radicals that can compromise many cellular functions. Among the many attributes of Bioflavonoids is their ability to support a healthy immune system response and to promote the maintenance of a healthy vascular system. This product is enhanced with Vitamin C for its synergistic effect.