Vitamin D2

Vitamin D2

"Calcidol" redirects here. For the form of vitamin D3 sometimes called "calcidiol", see Cholecalciferol.
CAS number 50-14-6 YesY
PubChem 5280793
ChemSpider 4444351 YesY
DrugBank DB00153
KEGG C05441 YesY
ChEBI CHEBI:28934 YesY
ATC code CC01
Jmol-3D images Image 1
Molecular formula C28H44O
Molar mass 396.65 g/mol
Melting point

114–118 °C

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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Ergocalciferol is a provitamin form of vitamin D, also called vitamin D2. In isolated manufactured formats, it is marketed under various names including Deltalin (Eli Lilly and Company), discontinued Drisdol (Sanofi-Synthelabo), and Calcidol (Patrin Pharma). Ergocalciferol is created when ultraviolet light activates ergosterol.

Ergocalciferol may be used as a vitamin D supplement, and a 2011 clinical guideline[1] considered it to be as effective as cholecalciferol (vitamin D3), which is produced naturally by the skin when exposed to ultraviolet light.

Conflicting evidence exists for how similarly D2 and D3 behave in the body and whether they are equally active or efficient in production of 25-hydroxyvitamin D (25(OH)D), the active hormone. Some preliminary studies indicate D3 is more potent,[2][3] while others report equal efficacy.[1][4][5] While both appear to have similar efficacy in ameliorating rickets,[6] vitamin D3 may have more potency for reducing falls in elderly patients. The metabolism of each is different, with the vitamin D binding protein (VDP) possibly having greater affinity for 25(OH)D3 than for 25(OH)D2, as shown in one study.[2] Cholecalciferol (vitamin D3) is sensitive to UV radiation and rapidly, but reversibly, forms other sterols which can further irreversibly convert to ergosterol.



  • 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).[7]

Fungus, from USDA nutrient database[8]

  • 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[9]

Ergocalciferol is produced in fungi synthetically through irradiation of ergosterol.[10] 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 to a vitamin D2 supplement.[11] Vitamin D2 from UV-irradiated yeast baked into bread is bioavailable.[12] By visual assessment or using a chromometer, no significant discoloration of irradiated mushrooms, as measured by the degree of "whiteness", was observed.[13] Claims have been made that a normal serving (approx. 3 oz or 1/2 cup, or 60 grams) of mushrooms treated with ultraviolet light provides vitamin D content to levels of 3,476 IU if exposed to just 5 minutes of UV light after being harvested.[14]

Preliminary research

One study found low vitamin D2 levels in patients with Alzheimer's disease,[15] but this observational study did not prove cause or effect related to ergocalciferol and vitamin D2 deficiency in the diet.


External links

  • NIST Chemistry WebBook page for ergocalciferol