Vitamin D2 vs D3
When choosing a vitamin D supplement, should you pick D2 or D3? D3 is superior in absorption and duration, but D2 can still be a useful choice in specific situations.
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The Short Answer
For most people, vitamin D3 (cholecalciferol) is the better choice. It is absorbed more efficiently, stays in the body longer, and raises blood vitamin D levels more effectively than D2. However, D2 (ergocalciferol) is still used in vegan supplements and certain prescription formulations.
Detailed Comparison
| Feature | Vitamin D2 | Vitamin D3 |
|---|---|---|
| Chemical Name | Ergocalciferol | Cholecalciferol |
| Source | Yeast, mushrooms, fortified foods | Animal products, lanolin (sheep wool) |
| Vegan-Friendly | Yes (from mushrooms/yeast) | Usually no (lanolin). Lichen-derived D3 is vegan |
| Absorption Efficiency | Lower | Higher (~2x D2) |
| Half-Life | Shorter (days to weeks) | Longer (weeks to months) |
| Blood Level Elevation | Less effective | More effective (~70-87% higher levels) |
| Cost | Generally cheaper | Slightly more expensive |
| Best For | Vegans (yeast-derived), prescription 50,000 IU weekly | Most people, general supplementation |
Key Differences Explained
1. Absorption and Duration
Research shows D3 is approximately twice as effective as D2 at raising blood 25(OH)D concentrations. D3 has a half-life of weeks to months, while D2 is much shorter. This means D3 maintains its effect longer between doses.
2. Vegan Options
Traditionally, D3 was extracted from lanolin (sheep wool fat), making it non-vegan. However, recent lichen-derived plant-based D3 supplements are now available, giving vegans a D3 option.
3. Prescription vs Over-the-Counter
In the United States, prescription high-dose vitamin D (typically 50,000 IU) is usually D2. However, since research shows D3 is more effective, ask your doctor about D3 prescriptions or consider over-the-counter D3 supplements.
Note: This information is for educational purposes only. Always consult a healthcare provider before starting vitamin D supplementation.