Ester-C is an advanced form of vitamin C that protects from acidity or stomach upsets accompanying other vitamin C products.
In Ester-C, the acid is ascorbic acid (vitamin C). Vitamin C is esterified with calcium and bioflavanoids (e.g. calcium ascorbate) to make it non-acidic. It is specially formulated for fast absorption and retention to obtain the maximum benefits of vitamin C quickly. It is both oil- and water-soluble and is absorbed 400% faster than regular vitamin C.