Ester-C is the unique immune health formula containing a proprietary, clinically studied Vitamin C that stays in your immune system for 24 hours. Ester-C Vitamin C is clinically shown to last longer than regular vitamin C. That's because Ester-C Vitamin C is carefully formulated to contain vitamin C metabolites, the same metabolites that are naturally produced by your body and help enhance the retention of vitamin C by your white blood cells, a vital part of your immune system. , , So once you take your daily dose of Ester-C Vitamin C, it gets into your white blood cells, and stays there - for up to 24 hours. Vitamin C also contributes to the health of your upper respiratory tract, plus, Ester-C Vitamin C is manufactured without chemicals to neutralize pH, which means it's non-acidic and gentle on your stomach. Ester-C is the kinda of support you can count on 24/7. , Ingredients - Calcium Silicate, Natural Palm Leaf Glaze, Vegetable Magnesium Stearate, Vegetable Stearic Acid. , Storage Instruction - Store at 18-23 degrees C