non acidic vitamin c ,reduces risk of tummy upsets,unique patented form of vitamin c,fast absorbed and well retained by the bodyester-c® is a unique patented form of vitamin c that is manufactured in the usa. it is believed that ester-c® may be an improved form of the vitamin, although opinions differ amongst experts. we were the first company to launch ester-c® in the uk and we are still selling it because there have been a number of compelling studies carried out with this novel form of vitamin c. ester-c® is non acidic (it has a neutral ph in solution), which means that it is certainly a very gentle form of vitamin c, which may be useful for those who experience intestinal difficulties when taking acidic forms of vitamin c.ester-c® is also described as a calcium ascorbate, but it is more than just this as the patented manufacturing process creates other compounds called \'metabolites\' of vitamin c, which are believed to impart certain properties to ester-c®