Skeletal formula of ergocalciferol
Ball-and-stick model of the ergocalciferol molecule
IUPAC name
Other names
Drisdol (Sanofi-Synthelabo), Calcidol (Patrin Pharma)
ATC code A11
ChemSpider  Y
DrugBank  Y
Jmol-3D images Image
Molar mass 396.65 g/mol
Melting point 114 to 118 °C (237 to 244 °F; 387 to 391 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 Y  (: Y/N?)

Ergocalciferol (vitamin D2) is a form of vitamin D. Ergocalciferol is a secosteroid formed by a photochemical bond breaking of a steroid, specifically, by the action of ultraviolet light on ergosterol. Viosterol, the name given to early preparations of irradiated ergosterol, is essentially synonymous with ergocalciferol.[1][2]

Ergocalciferol may be used as a vitamin D supplement, and a 2011 clinical guideline[3] considered it to be as effective as cholecalciferol (vitamin D3) which is produced naturally by the skin when exposed to ultraviolet light. It is manufactured and marketed under various names, including Deltalin (Eli Lilly and Company), Drisdol (Sanofi-Synthelabo) and Calcidol (Patrin Pharma).


  • Sources 1
  • Research concerning efficacy of vitamin D2 and D3 2
  • Preliminary research 3
  • References 4
  • External links 5



  • Cladina arbuscula specimens grown under different natural conditions: The contents of vitamin D3 range from 0.67 to 2.04 μg/g dry matter in the thalli of C. arbuscula specimens grown under different natural conditions, while provitamin D3 could not be detected. The ranges for provitamin D2 and vitamin D2 were 89-146 and 0.22-0.55 μg/g dry matter, respectively, while the contents of provitamin D3 were below the detection limit (0.01 μg/g dry matter).[4]

Fungus, from USDA nutrient database (per 100g) [5]

  • Mushrooms, portobello, exposed to ultraviolet light, raw: Vitamin D (D2 + D3): 11.2 µg (446 IU)
  • Mushrooms, portobello, exposed to ultraviolet light, grilled: Vitamin D (D2 + D3): 13.1 µg (524 IU)
  • Mushrooms, shiitake, dried: Vitamin D (D2 + D3): 3.9 μg (154 IU)
  • Mushrooms, shiitake, raw: Vitamin D (D2 + D3): 0.4 μg (18 IU)
  • Mushrooms, portobello, raw: Vitamin D (D2 + D3): 0.3 μg (10 IU)


  • Alfalfa (Medicago sativa subsp. sativa), shoot: 4.8 μg (192 IU) vitamin D2, 0.1 μg (4 IU) vitamin D3[6]

Ergocalciferol is produced in fungi synthetically through irradiation of ergosterol.[7] Human bioavailability of vitamin D2 from vitamin D2-enhanced button mushrooms via UV-B irradiation is effective in improving vitamin D status and not different from a vitamin D2 supplement.[8] Vitamin D2 from UV-irradiated yeast baked into bread is bioavailable.[9] By visual assessment or using a chromometer, no significant discoloration of irradiated mushrooms, as measured by the degree of "whiteness", was observed.[10] Claims that a normal serving of mushrooms treated with ultraviolet light provides the equivalent of 3,500 International Units of vitamin D when exposed to ultraviolet light after harvest have gained popular attention.[11]

Research concerning efficacy of vitamin D2 and D3

Conflicting evidence exists for how similarly D2 and D3 behave in the body and whether they are equally active or efficient in production of 1,25-hydroxyvitamin D (1,25(OH)D), the active hormone. Some preliminary studies indicate D3 is more potent,[12][13] while others report equal efficacy.[3][14][15] Both forms appear to have similar efficacy in ameliorating rickets[16] and reducing the incidence of falls in elderly patients.[17]

The metabolism of each appears to be different, with the vitamin D binding protein possibly having greater affinity for 25(OH)D3 than for 25(OH)D2, as shown in one study.[12] Cholecalciferol (vitamin D3) is sensitive to UV radiation and rapidly, but reversibly, forms other sterols which can further irreversibly convert to ergosterol.

Preliminary research

One study found low vitamin D2 levels in patients with Alzheimer's disease,[18] but this observational study did not prove cause or effect related to ergocalciferol and vitamin D2 deficiency in the diet.


  1. ^ Science Service (1930) Viosterol official name for irradiated ergosterol, J. Chem. Educ. 7(1) 166, DOI: 10.1021/ed007p166, see [, accessed 10 July 2014.
  2. ^ See "Viosterol" and "Calciferol" at Merriam-Webster Medical Dictionary, e.g., [3] and [4], accessed 10 July 2014.
  3. ^ a b Holick, M. F.; Binkley, N. C.; Bischoff-Ferrari, H. A.; Gordon, C. M.; Hanley, D. A.; Heaney, R. P.; Murad, M. H.; Weaver, C. M. (2011). "Evaluation, Treatment, and Prevention of Vitamin D Deficiency: An Endocrine Society Clinical Practice Guideline". Journal of Clinical Endocrinology & Metabolism 96 (7): 1911–1930.  
  4. ^ Wang, T; Bengtsson, G; Kärnefelt, I; Björn, LO (2001). "Provitamins and vitamins D₂and D₃in Cladina spp. Over a latitudinal gradient: Possible correlation with UV levels". Journal of photochemistry and photobiology. B, Biology 62 (1–2): 118–22.  
  5. ^ "use the keyword 'portabella' and then click submit"USDA nutrient database – . 
  6. ^ "Dr. Duke's Phytochemical and Ethnobotanical Databases". 
  7. ^ Simon, R. R.; Borzelleca, J. F.; Deluca, H. F.; Weaver, C. M. (2013). "Safety assessment of the post-harvest treatment of button mushrooms (Agaricus bisporus) using ultraviolet light". Food and Chemical Toxicology 56: 278–89.  
  8. ^ P Urbain, F Singler, G Ihorst, H-K Biesalski and H Bertz (August 2011). "Bioavailability of vitamin D2 from UV-B-irradiated button mushrooms in healthy adults deficient in serum 25-hydroxyvitamin D: a randomized controlled trial". European Journal of Clinical Nutrition 65 (8): 965–971.  
  9. ^ Hohman, E. E.; Martin, B. R.; Lachcik, P. J.; Gordon, D. T.; Fleet, J. C.; Weaver, C. M. (2011). "Bioavailability and Efficacy of Vitamin D2from UV-Irradiated Yeast in Growing, Vitamin D-Deficient Rats". Journal of Agricultural and Food Chemistry 59 (6): 2341–2346.  
  10. ^ Koyyalamudi, SR; Jeong, SC; Song, CH; Cho, KY; Pang, G (2009). "Vitamin D2 formation and bioavailability from Agaricus bisporus button mushrooms treated with ultraviolet irradiation". J Agric Food Chem 57 (8): 3351–5.  
  11. ^ "Bringing Mushrooms Out of the Dark". MSNBC. April 18, 2006. Retrieved 2007-08-06. 
  12. ^ a b Houghton, L.; Vieth, R. (2006). "The case against ergocalciferol (vitamin D2) as a vitamin supplement". The American Journal of Clinical Nutrition 84 (4): 694–697.  
  13. ^ Trang, H. M.; Cole, D. E.; Rubin, L. A.; Pierratos, A.; Siu, S.; Vieth, R. (1998). "Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2". The American journal of clinical nutrition 68 (4): 854–858.  
  14. ^ Holick, M. F.; Biancuzzo, R. M.; Chen, T. C.; Klein, E. K.; Young, A.; Bibuld, D.; Reitz, R.; Salameh, W.; Ameri, A.; Tannenbaum, A. D. (2007). "Vitamin D2 is as Effective as Vitamin D3 in Maintaining Circulating Concentrations of 25-Hydroxyvitamin D". Journal of Clinical Endocrinology & Metabolism 93 (3): 677–681.  
  15. ^ Biancuzzo, R. M.; Young, A.; Bibuld, D.; Cai, M. H.; Winter, M. R.; Klein, E. K.; Ameri, A.; Reitz, R.; Salameh, W.; Chen, T. C.; Holick, M. F. (2010). "Fortification of orange juice with vitamin D2 or vitamin D3 is as effective as an oral supplement in maintaining vitamin D status in adults". American Journal of Clinical Nutrition 91 (6): 1621–1626.  
  16. ^ Thacher, TD; Fischer, PR; Obadofin, MO; Levine, MA; Singh, RJ; Pettifor, JM (2010). "Comparison of Metabolism of Vitamins D2 and D3 in Children with Nutritional Rickets". Journal of Bone and Mineral Research 25 (9): 1988–1995.  
  17. ^ Fosnight, S. M.; Zafirau, W. J.; Hazelett, S. E. (2008). "Vitamin D Supplementation to Prevent Falls in the Elderly: Evidence and Practical Considerations". Pharmacotherapy 28 (2): 225–234.  
  18. ^ Iltaf Shah; Petroczi, Andrea; Tabet, Naji; Klugman, Anthony; Isaac, Mokhtar; p. Naughton, Declan (2012). "Low 25OH Vitamin D2 Levels Found in Untreated Alzheimer's Patients, Compared to Acetylcholinesterase-Inhibitor Treated and Controls". Current Alzheimer Research 9 (9): 1069–1076.  

External links

  • NIST Chemistry WebBook page for ergocalciferol