I eat low mercury fish such as salmon, sardines or herring, but only maybe 7 ounces a week or less. Ester C is good, although some criticize it. There are also other formulations of calcium ascorbate, and there is magnesium ascorbate. Magnesium ascorbate gives you magnesium with vitamin C in a buffered form. It makes it easy to add extra magnesium to your regimen.