A customized formulation of Ester-C with bioflavonoids. Ester-C is a patented nutritional product that contains ascorbic acid and calcium. This formulation is non-acidic and minimally irritating to the intestines. Esterol also provides 3 types of bioflavonoids - quercetin, rutin, and proanthocyanidins from grape seed extract. Ester-C vitamin C is corn-source.