Vitamin D3 (cholecalciferol) vs Vitamin D2 (ergocalciferol)
Almost all over-the-counter vitamin D is D3. Prescription vitamin D is often D2 because it's cheaper to produce at pharmaceutical scale. For raising and holding 25(OH)D levels, D3 wins.
Option A
Vitamin D3 (cholecalciferol)
VS
Option B
Vitamin D2 (ergocalciferol)
| Factor | Vitamin D3 (cholecalciferol) | Vitamin D2 (ergocalciferol) |
|---|---|---|
| Source | Animal (lanolin) or lichen | Yeast / fungi |
| Vegan option | Lichen-derived D3 | Yes (most forms) |
| Blood level raise | Reliable, durable | Weaker and shorter |
| Typical dose | 1000–4000 IU | Higher equivalent required |
| Half-life | Longer | Shorter |
| When prescribed | Most OTC bottles | Rx megadose (50,000 IU) |
When to pick each
Vitamin D3 (cholecalciferol)
Pick D3 if…
You want the form with the strongest evidence for raising and maintaining 25(OH)D. Lichen-derived D3 covers the vegan case without the efficacy penalty.
Vitamin D2 (ergocalciferol)
Pick D2 if…
Your prescriber specifically prescribed it, or you only have access to fungus-derived forms. Otherwise D3 is the default.
Frequently asked
- Is D3 always better than D2?
- For raising serum 25(OH)D and keeping it raised, yes. Both can correct deficiency, but D3 does it more efficiently per IU.
- How much vitamin D should I take?
- Most adults need 1000–4000 IU daily. Start with 2000 IU, retest in 12 weeks, aim for a serum level of 40–60 ng/mL.
- Do I need vitamin K2 with D3?
- Reasonable but not mandatory. K2 helps direct absorbed calcium to bones instead of arteries, which matters more at higher D3 doses and in older adults.
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