Objective A novel assay was employed to study the free 1, 25-dihydroxyvitamin D (1, 25
(OH) 2D) concentrations in various populations with different levels of 1, 25 (OH) 2D and …

Aging alters the metabolism of vitamin D and calcium in a number of ways. There is an age-
related decline in dermal production of 7-dehydrocholesterol, the precursor of previtamin …

Background It is assumed that calcium absorption decreases with age, but this is not well
documented. We report a study that addresses this issue. Objective The aim was to establish …

1, 25-Dihydroxyvitamin D3 [1, 25 (OH) 2D3] increases intestinal calcium absorption through
events that include binding of 1, 25 (OH) 2D3 to the intracellular vitamin D receptor. In vitro …

Calcium and phosphate regulate numerous biological processes and they are essential for
bone mass and bone quality. The calcium and phosphate balance largely depends on …

The absorptive response to graded doses of vitamin D3, 25 (OH) D, and 1, 25 (OH) 2D was
measured in healthy adult men after treatment periods of eight, four, and two weeks …

The finding that the link between polymorphism at the vitamin D receptor (VDR) gene and
rates of bone loss from the femoral neck in postmenopausal women is enhanced at low …

Objective Diurnal variations in plasma levels of 1, 25-dihydroxyvitamin D (1, 25 (OH) 2D)
have previously only been investigated in young individuals, and these studies have failed …

Vitamin D along with parathyroid hormone (PTH) and calcitonin (CT) are the three principal
effectors of calcium and phosphorus homeostasis. The secosteroid, vitamin D 3, is subject to …

Dihydroxyvitamin D [1, 25‐(OH) 2D] is the principal mediator of the biologic effects of vitamin
D. We showed previously that obese white subjects have low serum vitamin D and 25 …