American Health Ester-C with Citrus Bioflavonoids 1000 mg. - 120 Vegetarian Tablets American Health Ester-C with Citrus Bioflavonoids 1000 mg. is a breakthrough patented formula that contains naturally-occurring Vitamin C metabolites. American Health Ester C is quickly absorbed. American Health s Ester-C s unique manufacturing process neutralizes pH making it gentle on the digestive system.