Vitamin d2 vs vitamin d3
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Chemical Structure and Metabolism of Vitamin D2 vs Vitamin D3
Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) are chemically distinct. Vitamin D2 has a double bond between carbons 22 and 23 and a methyl group on carbon 24, while D3 does not. Despite these differences, both forms are converted in the body through the same enzymatic pathways to their active hormone forms, which are essential for calcium absorption and bone health .
Efficacy in Raising and Maintaining Vitamin D Status
Vitamin D3 Is More Effective Than D2
Multiple studies and systematic reviews have shown that vitamin D3 is more effective than vitamin D2 at raising and maintaining serum 25-hydroxyvitamin D [25(OH)D] levels, which is the main marker of vitamin D status. Large randomized controlled trials and meta-analyses found that vitamin D3 supplementation leads to a greater and more sustained increase in 25(OH)D compared to vitamin D2, both when given as a single large dose (bolus) and in daily low doses 2568+2 MORE. For example, one study found that D3 increased vitamin D status by 74–75%, while D2 only increased it by 33–34% at a low daily dose over 12 weeks 29.
Some Studies Show Similar Effectiveness
However, not all research agrees. Some studies have found that daily supplementation with 1000 IU of either D2 or D3 was equally effective in maintaining serum 25(OH)D levels over 11 weeks, suggesting that at certain doses and durations, both forms can be similarly effective . This highlights that the difference in efficacy may depend on the dose, frequency, and population studied.
Impact on Vitamin D Metabolism
Vitamin D2 not only raises total 25(OH)D less effectively than D3, but it may also suppress the body’s own vitamin D3 and its metabolites. In one trial, vitamin D2 supplementation reduced levels of 25(OH)D3 and other active vitamin D3 metabolites, while D3 supplementation increased them . This suggests that D2 may interfere with the metabolism of D3 in the body.
Public Health and Supplementation Considerations
Most evidence supports the use of vitamin D3 over D2 for supplementation and food fortification, as D3 is generally more effective at improving vitamin D status 1269+1 MORE. However, D2 is still recognized as an acceptable source of vitamin D in foods and supplements, and may be preferred for those following vegan diets, since D3 is usually derived from animal sources 410.
Conclusion
Overall, vitamin D3 is more effective than vitamin D2 at raising and maintaining vitamin D levels in most situations, especially at low doses and with bolus administration. While both forms are accepted for supplementation, D3 is generally the preferred choice for optimizing vitamin D status, though D2 remains important for those with dietary restrictions 1256+3 MORE.
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