Multiple sources of dietary calcium-some aspects of its essentiality.

The increasing recognition of the important role of calcium in the myriad regulation of cellular processes in the health and well being throughout one's lifetime has focused on the need to ensure a sufficiency of its intake for nutritional, physiological, and medical reasons. Additionally, the recognition of the dynamic dietary changes and preferences of various populations in terms of their consumption of calcium-containing products coupled with large variations of food patterns and availability of calcium, highlights the need to consider and evaluate multiple sources of calcium (dairy, non-dairy, fortified foods, and supplemental). Aspects of the essentiality of calcium are thus considered via an initial consideration of: the salient aspects of absorption and bioavailability, changes in individual and societal dietary habits and preferences and the evaluation of various RDAs, AIs, and DRIs for calcium.