Dietary supplement. TwinLab Ester-C 1000 with Citrus Bioflavonoid Complex is a unique ascorbate complex bound to calcium from calcium carbonate. This special form of Vitamin C is pH neutral (non-acidic) and contains naturally occurring metabolites. It is naturally processed in purified water without the use of alcohol or acetone solvents. This product also contains a citrus bioflavonoid complex. Each Ester-C 1000 with Citrus Bioflavonoid Complex tablet contains the highest quality ingredients. This product is manufactured at our own state-of-the-art facility with stringent quality control. 100% Vegetarian tablets. Ester-C 1000 with Citrus Bioflavanoid Complex is free of sugars, salt (sodium), wheat, starch, yeast, dairy, artificial colors, flavors and preservatives.