, non acidic vitamin c, reduces risk of tummy upsets, unique patented form of vitamin c, fast absorbed & 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 enhanced form of the vitamin although opinions differ amongst experts. we were the first company to launch ester-c® in the uk & 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®