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Evidence-Based Comparison
Vitamin D3 vs Vitamin D2: Absorption, Sources & Evidence Compared
Which form of Vitamin D is more effective at raising serum 25(OH)D levels?
Key Takeaway (TL;DR)
Clinical meta-analyses show that Vitamin D3 is significantly more effective at raising and sustaining circulating 25(OH)D levels than Vitamin D2. D3 is generally recommended unless dietary restrictions mandate plant-based D2 (or vegan algal D3).
Winner: Vitamin D3 offers superior bioavailability and longer half-life.
Detailed Comparison
| Criteria | Vitamin D3 (Cholecalciferol) | Vitamin D2 (Ergocalciferol) |
|---|---|---|
| Source | Lanolin, fatty fish, or microalgae | UV-irradiated yeast and mushrooms |
| Bioavailability | High (identical to human synthesized form) | Moderate (requires additional conversion) |
| Potency at raising 25(OH)D | Significantly higher (~1.7x to 3x potency) | Lower; clears faster from circulation |
| Vegan Suitability | Non-vegan by default, but vegan algal D3 is available | 100% Vegan friendly |
| Recommended Daily Dose | 400 - 1000 IU/day (Upper Limit: 4000 IU) | 400 - 1000 IU/day (Upper Limit: 4000 IU) |
| Best Timing | With fat-containing meals | With fat-containing meals |
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Includes RDA limits, side effects, and all PubMed trials.
Frequently Asked Questions
Why do clinicians prefer Vitamin D3 over D2?
Evidence demonstrates that Vitamin D3 binds with higher affinity to vitamin D-binding protein (DBP) compared to D2, leading to sustained serum concentrations and faster correction of deficiency.
Can vegans take Vitamin D3?
Yes, vegan Vitamin D3 sourced from lichen or algae is widely available today, offering the superior absorption of D3 without animal-derived lanolin.
This comparison is synthesized from peer-reviewed scientific literature and public health authority guidelines for informational purposes only. Consult a healthcare professional before altering supplementation.