There is a huge great confusion about calcium. The whole world has been told to drink milk to get calcium when in fact too much dairy actually leaches calcium out of your bones.... One of calcium's main jobs (apart from being part of your bones) is to buffer the body when it becomes too acidic. Eating heavy meals every day containing foods like meat and dairy and Sugar make the body acid ... that's when calcium is called upon to neutralize the acid state. The Master Cleanse is a very light burden on the digestive system and because of the dilution is probably not for affecting on the pH of the body system. It does apparently have a good source of three essential elements; calcium, iron and thiamin and also a high ratio of potassium to sodium which is also good. For the length of time you are on the cleanse I wouldn't worry about mineral status compared to the benefits of toxin loss.