Vitamin C and bioflavonoids occur together in nature with one of the richest sources of this combination being found in the pulp and peel of citrus fruits and vegetables while rutin is a bioflavonoid and is found in high amounts in rye. Bioflavonoids are naturally occurring organic plant elements that appear to act synergistically with Vitamin C , increasing its availability and action, and are particularly important in maintaining the integrity of blood vessels as they contribute to the integrity of collagen while some bioflavonoids have antioxidant properties similar to those of vitamin C , and have been shown to protect vitamin C and adrenaline from the oxidative action of copper-containing enzymes.