title: Measuring calcium absorption and utilization in humans.
abstract: OBJECTIVE
  Calcium metabolism is comprised primarily of absorption, urinary excretion, endogenous secretion and bone turnover. This review evaluates recent findings relating to the role of genetic and environmental factors, especially diet, on perturbing parameters of calcium metabolism. Calcium dynamics are studied with the use of isotopic tracers. We also cover state-of-the-art methods for stable calcium isotope ratio analysis and offer insights on experimental design.
  
  
  RESULTS
  Some progress has been made identifying genetic and hormonal regulators of calcium absorption. Much progress has been made in understanding the role of diet on influencing calcium retention, especially with regard to dietary protein and salt. Long-held views on dietary factors thought to contribute to bone loss through urinary calcium loss have been shown to have no impact on net calcium retention because of compensatory changes in other aspects of calcium metabolism.
  
  
  CONCLUSIONS
  Much more work needs to be done on understanding genetic regulators of calcium metabolism. Despite recent advances in our knowledge of dietary influences on calcium metabolism, more studies are needed on the role of environmental factors, especially physical activity.
authors.affiliation: Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana 47907-2059, USA. weavercm@purdue.edu
authors.forename: Connie M
authors.initials: CM
authors.lastname: Weaver
authors.forename: Arlene P
authors.initials: AP
authors.lastname: Rothwell
authors.forename: Karl V
authors.initials: KV
authors.lastname: Wood
mesh_terms: D001128:Argon; D001842:Bone and Bones / Q000378:metabolism*; D002127:Calcium Isotopes; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000652:urine; D004032:Diet; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007408:Intestinal Absorption; D013058:Mass Spectrometry / Q000379:methods; D009753:Nutritive Value
chemical_list: D002127:Calcium Isotopes; D002136:Calcium, Dietary; D001128:Argon