Calcium intake and bone health throughout life.

Calcium requirement varies with stage of growth, with physiological drains (eg, pregnancy and lactation), and with factors that influence absorption and excretory loss (eg, gonadal hormone status and sodium and protein intakes). While for certain life-stages the cited requirement values are higher than currently recommended, they are below the intakes of both contemporary hunter-gatherers and our closest primate relatives, after adjusting for body size. Hence, they can be considered high only in comparison with current US practices. However, it also needs to be emphasized that bone health is a multifactorial affair and that meeting calcium requirements alone will neither guarantee optimal bone growth nor protect against bone loss if other critical factors are missing. For example, calcium affords only minimal protection against either immobilization or estrogen-withdrawal bone loss. Thus, while assuring an adequate calcium intake remains a sound strategy, it cannot be considered a panacea.