Powerful Immune Support . Solaray Reacta-C is packed with 500 mg of vitamin C plus 200 mg of bioflavonoid concentrate and a vitamin C support base of hesperidin, rutin, acerola cherry, and Indole-3-Carbinol for enhanced, synergistic support. Nutrient Rich Immunity Vitamins. The vitamin C in this formula is from a complex of strontium ascorbate and calcium ascorbate that is non acidic and designed to be fast-acting and long lasting. formulas made to provide 24 hours of highly bioavailable immune functions support.