Vitamin D: Role in the calcium and phosphorus economies

Robert P. Heaney

Research output: Chapter in Book/Report/Conference proceedingChapter

7 Scopus citations


Vitamin D functions in many body systems, but perhaps the best attested of the nutrient's actions-and certainly the one first associated with human disease-is its role in transferring calcium (and phosphorus) from ingested food into the body fluids. In this capacity, vitamin D functions as a part of a control system that operates to maintain constancy of the calcium ion concentrations in the extracellular fluid against the demands of obligatory excretory losses and skeletal mineralization. In both transfers, vitamin D works in concert with parathyroid hormone. Quantitative analysis of the inputs and drains of the calcium economy reveals that, at contemporary calcium intakes, D-mediated absorptive enhancement only partially mitigates the impact of low calcium intake or large calcium losses. While 1,25(OH)2D is clearly the most potent form of the vitamin, 25(OH) D exerts significant vitamin-D-like activity in its own right at physiological serum levels. Optimal vitamin D status is operationally defined as a level of D intake (or production) high enough to ensure that the D-mediated transfers are not limited by D availability. However, at intakes closer to those prevailing during hominid evolution, minor shifts in vitamin D mediated absorption are fully adequate to compensate for stresses on the calcium economy.

Original languageEnglish (US)
Title of host publicationVitamin D
PublisherElsevier Inc.
Number of pages18
ISBN (Print)9780123819789
StatePublished - 2011

All Science Journal Classification (ASJC) codes

  • Dentistry(all)
  • Medicine(all)


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