Absorbable, Stomach Friendly, Vitamin C For Immune System Support Ester-C Is A Natural, Buffered Form Of Vitamin C Designed For Maximum Absorption Without Stomach Upset. Since It Has A Neutral Ph, Ester-C Will Not Contribute To The Formation Of Stomach Erosions Like The Common Form Of Vitamin C, Ascorbic Acid, Can. • Dose: Administer 1 Scoop (5 Grams) Per Horse Per Day Or As Directed By Your Veterinarian Or Equine Nutritionist.