This chapter deals with the history of calcium and its metabolism in adult humans. It should be read in conjunction with Chapter IV.D.4 on osteoporosis, which contains a further discussion of calcium requirements and the effects of a deficiency in adults, and with Chapter IV.A.4 on vitamin D, which deals with the history of rickets, a disease caused in part by a deficiency of calcium resulting from reduced intake or poor absorption.

Historical Aspects

Bone is the main depository of calcium. Fully 99 percent of the body’s calcium is in the skeleton, with the rest in extracellular fluid and soft tissues. As early as the sixteenth century, it was recognized by a Dutch physician that the skeleton is not an inactive but a dynamic tissue under hormonal influence and capable of remodeling throughout life (Lutwak, Singer, and Urist 1974). Two specific types of bone cells acted upon in these processes are the osteoblasts (involved in bone formation) and the osteoclasts (involved in bone resorption).

Another important discovery in the history of calcium was made by Sidney Ringer more than 100 years ago. He demonstrated that the contractility of cardiac muscle was stimulated and maintained by the addition of calcium to the perfusion fluid (Ringer 1883). It has also been shown that this important effect of calcium is not limited to cardiac muscle but has a generalized, activating effect in practically all differentiated cells (Opie 1980; Rubin 1982; Campbell 1986). However, in addition to calcium, the presence of specific concentrations of sodium and potassium are needed to achieve this effect (Mines 1911; Lowenstein and Rose 1978).