Ester-C is a patented form of Vitamin C. It provides 24-hour immune support, is non-acidic, and contains naturally-occurring metabolites for quick absorption. Ester-C is the most patented Vitamin C brand in the world and, since its benefits are supported by science, you know you are giving your body the advanced immune support it shouldn't be without. Ester-C along with Citrus bioflavonoid delivers advanced antioxidant protection, remaining active in the Immune system for up to 24 hours! 24-Hou