Ergocalciferol may be used as a vitamin D
supplement, whereas
cholecalciferol (vitamin D3) is produced naturally by the skin when exposed to ultraviolet light.[15] Ergocalciferol (D2) and cholecalciferol (D3) are considered to be equivalent for vitamin D production, as both forms appear to have similar efficacy in ameliorating
rickets[16] and reducing the incidence of falls in elderly patients.[17] Conflicting reports exist, however, concerning the relative effectiveness, with some studies suggesting that ergocalciferol has less efficacy based on limitations in absorption, binding, and inactivation.[18] A
meta-analysis concluded that evidence usually favors cholecalciferol in raising vitamin D levels in blood, although it stated more research is needed.[18]
Like
cholecalciferol, ergocalciferol is inactive by itself. It requires two
hydroxylations to become active: the first in the liver by
CYP2R1 to form 25-hydroxyergocalciferol (ercalcidiol or 25-OH D2[20]), and the second in the kidney by
CYP27B1, to form the active 1,25-dihydroxyergocalciferol (ercalcitriol or 1,25-(OH)2D2), which activates the
vitamin D receptor.[21] Unlike
cholecalciferol, 25-hydroxylation is not performed by
CYP27A1 for ergocalciferol.[22]
Ergocalciferol and metabolites have lower affinity to the
vitamin D-binding protein compared to the D3 counterparts. The binding affinity of ercalcitriol to the vitamin D receptor is similar to that of
calcitriol.[22] Ergocalciferol itself and metabolites can be deactivated by 24-hydroxylation.[23]
Sources
Fungus, from USDA nutrient database (per 100g), D2 + D3:[24][25]
Cladina arbuscula specimens grown under different natural conditions contain provitamin D2 and vitamin D2, ranges 89-146 and 0.22-0.55 μg/g dry matter respectively. They also contain vitamin D3 (range 0.67 to 2.04 μg/g) although provitamin D3 could not be detected. Vitamin D levels correlate positively with UV irradiation.[26]
The vitamin D2 content in mushrooms and C. arbuscula increase with exposure to ultraviolet light.[26][28]Ergosterol (provitamin D2) found in these fungi is converted to previtamin D2 on UV exposure, which then turns into vitamin D2. As cultured mushrooms are generally grown in darkness, less vitamin D2 is found compared to those grown in the wild or dried in the sun.[19]
When fresh mushrooms or dried powders are purposely exposed to ultraviolet light, vitamin D2 levels can be concentrated to much higher levels.[29][30][31] The irradiation procedure does not cause significant discoloration, or whitening, of mushrooms.[32] Claims have been made that a normal serving (approx. 2 oz or 60 grams) of fresh mushrooms treated with ultraviolet light have increased vitamin D content to levels up to 80 micrograms or 3200 IU if exposed to just five minutes of UV light after being harvested.[30]
Button mushrooms with enhanced vitamin D2 content produced this way functions similarly to a vitamin D2 supplement; both effectively improves vitamin D status.[29][33] Vitamin D2 from UV-irradiated yeast baked into bread or mushrooms is bioavailable and increases blood levels of 25(OH)D.[29]
Names
Viosterol, the name given to early preparations of irradiated ergosterol, is essentially synonymous with ergocalciferol.[34][35] However, currently, Viosterol is also the brand name for
cholecalciferol (vitamin D3) in some countries.[36][37]
Ergocalciferol is manufactured and marketed under various names, including Deltalin (
Eli Lilly and Company), Drisdol (Sanofi-Synthelabo), and Calcidol (Patrin Pharma).
^World Health Organization (2021). World Health Organization model list of essential medicines: 22nd list (2021). Geneva: World Health Organization.
hdl:10665/345533. WHO/MHP/HPS/EML/2021.02.
^Haytowitz DB (2009).
"Vitamin D in mushrooms"(PDF). Nutrient Data Laboratory, US Department of Agriculture.
Archived(PDF) from the original on 1 February 2021. Retrieved 16 April 2018.
^Haytowitz DB (2009).
"Vitamin D in mushrooms"(PDF). Nutrient Data Laboratory, US Department of Agriculture.
Archived(PDF) from the original on 1 February 2021. Retrieved 16 April 2018.
^Simon RR, Borzelleca JF, DeLuca HF, Weaver CM (June 2013). "Safety assessment of the post-harvest treatment of button mushrooms (Agaricus bisporus) using ultraviolet light". Food and Chemical Toxicology. 56: 278–289.
doi:
10.1016/j.fct.2013.02.009.
PMID23485617.
^Koyyalamudi SR, Jeong SC, Song CH, Cho KY, Pang G (April 2009). "Vitamin D2 formation and bioavailability from Agaricus bisporus button mushrooms treated with ultraviolet irradiation". Journal of Agricultural and Food Chemistry. 57 (8): 3351–3355.
doi:
10.1021/jf803908q.
PMID19281276.
^See "Viosterol" and "Calciferol" at Merriam-Webster Medical Dictionary, e.g.,
"Medical Definition of VIOSTEROL".
Archived from the original on 14 July 2014. Retrieved 10 July 2014. and
"Definition of CALCIFEROL".
Archived from the original on 14 July 2014. Retrieved 10 July 2014., accessed 10 July 2014.