Vitamin D and calcium interactions: functional outcomes.

I present the results of published studies and original data and describe the functional outcomes of effects related to the interaction between vitamin D status and calcium intake. These effects fall into 3 broad categories: 1) synergistic effects of vitamin D status and calcium intake on calcium absorption; 2) effects of calcium intake on vitamin D status; and 3) largely observational data suggesting an association between calcium and vitamin D status and nonskeletal outcomes, such as cancer. To a considerable extent, both vitamin D status and the benefits associated therewith appear to be dependent on, or at least augmented by, calcium intakes at or above currently recommended levels.