Calciferol vs. Cholecalciferol: Key Differences in Vitamin D2 & D3
Calciferol is the generic name for vitamin D2 (ergocalciferol), while Cholecalciferol is vitamin D3—the form your skin makes from sunlight. Both raise blood levels of 25-hydroxy-vitamin D, yet they are chemically different molecules.
Shoppers squint at pharmacy shelves: “D2 or D3?” Labels scream “vitamin D” without clarifying which. Doctors swap terms in scripts, influencers mix them in posts, and supplement ads blur the line, so people grab either bottle assuming equivalence.
Key Differences
D2 comes from UV-irradiated yeast or mushrooms; D3 is sourced from lanolin or fish oil. D3 binds more tightly to vitamin-D-binding protein, stays in circulation longer, and raises serum 25(OH)D about 87 % more effectively per microgram than D2.
Which One Should You Choose?
Unless you’re vegan, choose Cholecalciferol (D3) for daily or high-dose repletion. Evidence shows it sustains levels longer and cuts deficiency risk faster. Vegans can opt for lichen-derived D3 or accept D2 if no alternative exists.
Can I take both together?
Yes, but dosing must account for the total IU to avoid toxicity.
Is prescription vitamin D always D2?
Historically yes, yet many prescribers now order D3 capsules or liquids.