Unique gentle form of vitamin C Patented formula Immune system support Non-acidic Ester-C is a breakthrough patented formula that contains naturally-occurring Vitamin C metabolites and is quickly absorbed. Its unique manufacturing process neutralises pH, making it gentle on the digestive system. Unique gentle form of vitamin C Patented formula Immune system support Non-acidic Ester-C is a breakthrough patented formula that contains naturally-occurring Vitamin C metabolites and is quickly absorbed. Its unique manufacturing process neutralises pH, making it gentle on the digestive system.