Solgar Ester-C Plus 500 mg Vitamin C Vegetable Capsules is a unique Vitamin C clinically-shown to Last longer inside your white blood cells - up to 24 hours. Solgar Ester-C Plus is exclusively formulated by Solgar and provides a patented, pH neutral (non-acidic) Vitamin C that is gentle on the stomach. The Vitamin C metabolites in Ester-C positively impact the retention of Vitamin C in cells, providing additional benefits. A special manufacturing process is employed to form a unique calcium ascorbate metabolite complex. This well-retained complex yields beneficial antioxidant and immune system support and incorporates natural bioflavonoids and acerola berry along with rose hips fruit powder. Unlike regular vitamin C such as Ascorbic Acid, Ester-C® is a unique Vitamin C clinically-shown to last longer inside your white blood cells-up to 24 hours.