Vitamin d2
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Efficacy of Vitamin D2 Compared to Vitamin D3
Introduction to Vitamin D2 and D3
Vitamin D is essential for maintaining bone health and supporting the immune system. There are two primary forms of vitamin D: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Despite their structural similarities, there has been ongoing debate about their relative efficacy in maintaining adequate vitamin D levels in the body.
Comparative Efficacy of Vitamin D2 and D3
Vitamin D2 and D3 in Maintaining Serum 25-Hydroxyvitamin D Levels
Several studies have investigated whether vitamin D2 is as effective as vitamin D3 in maintaining serum 25-hydroxyvitamin D [25(OH)D] levels. A randomized, placebo-controlled study found that a daily dose of 1000 IU of vitamin D2 was as effective as 1000 IU of vitamin D3 in maintaining serum 25(OH)D levels over an 11-week period1. However, other research suggests that vitamin D3 is more effective. For instance, a study comparing the effects of 15 µg/day of vitamin D2 and D3 found that vitamin D3 was significantly more effective in increasing serum 25(OH)D levels in both South Asian and white European women over the winter months2 3.
Long-Term Efficacy and Potency
Long-term studies have also shown that vitamin D3 is more potent than vitamin D2. A study conducted over 25 weeks demonstrated that vitamin D3 was more effective in maintaining serum 25(OH)D levels during the winter months compared to vitamin D26. Another study found that vitamin D3 increased serum 25(OH)D concentrations more than vitamin D2 when administered at a high dose of 50,000 IU per week for 12 weeks5.
Meta-Analyses and Systematic Reviews
Meta-analyses and systematic reviews have consistently shown that vitamin D3 is more effective than vitamin D2 in raising serum 25(OH)D levels. A meta-analysis of randomized controlled trials indicated that vitamin D3 had a significant and positive effect on raising serum 25(OH)D concentrations compared to vitamin D27. Another systematic review concluded that vitamin D3 was more efficacious in improving vitamin D status and regulating parathyroid hormone (PTH) levels, regardless of participant demographics, dosage, and vehicle of supplementation10.
Bioavailability and Metabolic Pathways
The bioavailability of vitamin D2 and D3 also differs. A study on the bioavailability of these vitamins found that vitamin D3 increased total 25(OH)D concentrations more than vitamin D2, and vitamin D2 supplementation was associated with a decrease in 25(OH)D3 levels8. This difference in bioavailability may explain why vitamin D3 is generally more effective in raising and maintaining serum 25(OH)D levels.
Safety of High-Dose Vitamin D Supplementation
Long-term high-dose vitamin D supplementation has been studied for its safety profile. A systematic review of randomized controlled trials found that high-dose vitamin D2 or D3 supplementation for one year or longer did not significantly increase the risk of total adverse events or kidney stones, although there was a trend towards increased hypercalcemia9.
Conclusion
In summary, while vitamin D2 can be effective in maintaining serum 25(OH)D levels, the majority of research indicates that vitamin D3 is more potent and effective, especially at higher doses and over longer periods. Given its greater efficacy and lower cost, vitamin D3 is generally recommended as the preferred form of supplementation to correct vitamin D deficiency.
Sources and full results
Most relevant research papers on this topic
Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D.
Vitamin D2 is as effective as vitamin D3 in maintaining serum 25-hydroxyvitamin D levels and does not negatively influence D3 levels.
RCT
Rigorous Journal
Highly CitedDaily supplementation with 15 μg vitamin D2 compared with vitamin D3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial.
Vitamin D3 is more effective than vitamin D2 in increasing serum 25(OH)D in wintertime, making it a preferential form for optimizing vitamin D status in the general population.
RCT
Large Human Trial
Very Rigorous JournalHighly CitedVitamin D2 vs. vitamin D3: They are not one and the same
Vitamin D3 is more than twice as effective as vitamin D2 at raising vitamin D levels, when given at a low dose in a physiologically relevant and public health-friendly manner.
Meta-AnalysisVitamin D requirements during lactation: high-dose maternal supplementation as therapy to prevent hypovitaminosis D for both the mother and the nursing infant.
High-dose maternal vitamin D2 supplementation during lactation safely increases circulating 25-hydroxyvitamin D concentrations, improving both maternal and nursing infants' nutritional vitamin D status.
RCTHighly CitedVitamin D(3) is more potent than vitamin D(2) in humans.
D3 is 87% more potent in raising and maintaining serum 25(OH)D concentrations and produces 2- to 3-fold greater storage of vitamin D than equimolar D2, making it the preferred treatment option for vitamin D deficiency.
RCTVery Rigorous JournalHighly CitedLong-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months
Daily vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over winter months in healthy adults.
RCTVery Rigorous JournalHighly CitedComparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis
Vitamin D3 supplementation is more effective at raising serum 25-hydroxyvitamin D concentrations than vitamin D2, potentially making it the preferred choice for supplementation.
Meta-AnalysisVery Rigorous JournalHighly CitedBioavailability of vitamin D(2) and D(3) in healthy volunteers, a randomized placebo-controlled trial.
Vitamin D3 increases total 25(OH)D concentration more than vitamin D2, while vitamin D2 supplementation leads to a decrease in 25(OH)D3, explaining the different effect on total 25(OH)D.
RCTRigorous JournalHighly CitedAdverse events from large dose vitamin D supplementation taken for one year or longer
Long-term high-dose vitamin D supplementation did not significantly increase the risk of total adverse events or kidney stones, but there was a trend towards increased hypercalcemia and possibly hypercalciuria.
Systematic ReviewRelative Efficacy of Vitamin D2 and Vitamin D3 in Improving Vitamin D Status: Systematic Review and Meta-Analysis
Cholecalciferol is more effective than ergocalciferol in improving vitamin D status and regulating PTH levels, regardless of participant demographics, dosage, and supplementation vehicle.
Meta-AnalysisVery Rigorous Journal