Older standards suggested getting twice as much calcium as magnesium. This was based on the ratio of the two minerals in the blood, and does not necessarily reflect dietary needs. Variations in absorption, utilization, and the physiology of the two minerals make the blood levels unreliable figures for determining dietary needs.

Magnesium deficiencies are quite common, marginal deficiencies are difficult to detect, and long-term consequences of low magnesium intake are quite serious. They include neurologic, heart and kidney diseases. For these reasons I recommend at least as much magnesium as calcium. High calcium intake also increases the need for magnesium.

A healthy diet naturally contains a lot of potassium. However, people taking certain diuretics or those eating a large amount of salt may need potassium supplements.