CAS number  YesY
ChemSpider  YesY
ATC code A11
Jmol-3D images Image 1
Molecular formula C27H44O2
Molar mass 400.64 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N   YesY/N?)

Alfacalcidol (or 1-hydroxycholecalciferol) is an analogue of vitamin D used for supplementation in humans and as a poultry feed additive.

Alfacalcidol has a weaker impact on calcium metabolism[1] and parathyroid hormone levels[2] than calcitriol, however alfacalcidiol has significant effects on the immune system, including regulatory T cells.[3] It is considered to be a more useful form of vitamin D supplementation, mostly due to much longer half-life and lower kidney load.[4]

Used as a poultry feed additive, it prevents tibial dyschondroplasia and increases phytate bioavailability.[5]


  1. ^ Biological effects of various regimes of 25-hydroxyvitamin D3 (calcidiol) administration on bone mineral metabolism in postmenopausal women, Clin Cases Miner Bone Metab. 2009 May–Aug; 6(2): 169–173; [1]
  2. ^ Oral calcitriol versus oral alfacalcidol for the treatment of secondary hyperparathyroidism in patients receiving hemodialysis: a randomized, crossover trial, Can J ,Clin Pharmacol Vol 15 (1) Winter 2008:e36 -e43; January 9, 2008; [2]
  3. ^ Alfacalcidol treatment restores derailed immune-regulation in patients with undifferentiated connective tissue disease, Autoimmunity Reviews, August 2010;
  4. ^ Superiority of alfacalcidol compared to vitamin D plus calcium in lumbar bone mineral density in postmenopausal osteoporosis, Rheumatol Int. 2006 Mar;26(5):445-53. Epub 2005 Nov 10; [3]
  5. ^ VDI Product Data