Calcium ions are used as the main co-enzyme to adjust the pH of digesting foods as they enter the blood stream. If you dont have them in your body, your body will rob calcium from your bones to get the calcium it needs. Calcium in it s purest form has a pH of 12. Calcium as a carbonate has a much lower pH than elemental calcium therefore it does not work properly as a co-enzyme. This will explain why people can take calcium carbonate all day long while their bodies rob calcium from their bone structure causing a condition known as osteoporosis. Calcium carbonate is black-board chalk, it s the scale that builds up on your shower wall, it gums up your swamp cooler, it does not mix with water and tends to gum up your circulation system...A person can have high sodium levels and never have high blood pressure if his calcium levels are normal." Rhett Bergeron, M.D.