Gentle and Non-Acidic Patented Vitamin C Formula 100% Vegetarian 500 mg with Citrus Bioflavonoids 24-Hour Immune Support Dietary Supplement Ester-C is a breakthrough patented Vitamin C formula supported with 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.