Ester-C is a unique, breakthrough Vitamin C formula containing naturally occurring metabolites. Metabolites help enhance the retention of Vitamin C by your white blood cells, an important part of your immune system. Ester-C’s water-based manufacturing process neutralizes pH, making it non-acidic & gentle on the stomach. In a daily 1,000 mg dose, Ester-C delivers 24-hour immune support… so once a day is all you need.