title: Vitamin D and intestinal calcium absorption.
abstract: The principal function of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. Calcium is absorbed by both an active transcellular pathway, which is energy dependent, and by a passive paracellular pathway through tight junctions. 1,25Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) the hormonally active form of vitamin D, through its genomic actions, is the major stimulator of active intestinal calcium absorption which involves calcium influx, translocation of calcium through the interior of the enterocyte and basolateral extrusion of calcium by the intestinal plasma membrane pump. This article reviews recent studies that have challenged the traditional model of vitamin D mediated transcellular calcium absorption and the crucial role of specific calcium transport proteins in intestinal calcium absorption. There is also increasing evidence that 1,25(OH)(2)D(3) can enhance paracellular calcium diffusion. The influence of estrogen, prolactin, glucocorticoids and aging on intestinal calcium absorption and the role of the distal intestine in vitamin D mediated intestinal calcium absorption are also discussed.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School and Graduate School of Biomedical Sciences, Newark, NJ 07103, USA. christak@umdnj.edu
authors.forename: Sylvia
authors.initials: S
authors.lastname: Christakos
authors.forename: Puneet
authors.initials: P
authors.lastname: Dhawan
authors.forename: Angela
authors.initials: A
authors.lastname: Porta
authors.forename: Leila J
authors.initials: LJ
authors.lastname: Mady
authors.forename: Tanya
authors.initials: T
authors.lastname: Seth
mesh_terms: D000367:Age Factors; D000375:Aging; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D004967:Estrogens / Q000097:blood; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology; D006706:Homeostasis; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects / Q000502:physiology*; D007413:Intestinal Mucosa / Q000378:metabolism*; D007774:Lactation / Q000378:metabolism; D011247:Pregnancy; D011388:Prolactin / Q000097:blood; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D004967:Estrogens; D005938:Glucocorticoids; D014807:Vitamin D; D011388:Prolactin; D002118:Calcium