WHAT TYPES OF VITAMIN D ARE THERE?
With regard to the form of vitamin D to be taken, systematic and meta-analytical evidence indicates that vitamin D3 (cholecalciferol) is more effective at raising 25(OH)D levels than D2 (ergocalciferol).1 Vitamin D3 supplementation in doses of 25µg (1000IU) daily for 25 weeks beginning at the end of Summer has also been found to be more effective at maintaining 25(OH)D levels through the winter than D2.2 In terms of half-life, vitamin D3 also appears to be more effective at sustaining 25(OH)D levels in the longer-term.3 The relative potencies of the two forms were reported as D3:D2 ; 9.5:14
- Tripkovic L, et al. (2012) Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr.; 95(6): 1357-64.
- Logan VF, et al. (2013). Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months. Br J Nutr.; 109(6): 1082-8.
- Oliveri B, et al. (2015). Vitamin D3 seems more appropriate than D2 to sustain adequate levels of 25OHD: a pharmacokinetic approach. Eur J Clin Nutr.; 69(6): 697-702
- Laura et al. J Clin Endocrinol Metab, November 2004, 89(11):5387--5391