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 has a neutral pH, making it non-acidic and 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. Added Citrus Bioflavonoids may help your body better absorb and utilize Vitamin C.