Vitamins D3 and D2
Milk is fortified with vitamin D3 (or cholecalciferol). This form of vitamin D is considered the most effective in humans.1
Studies have shown that vitamin D3 is twice as effective as vitamin D2 in increasing and maintaining serum concentrations of 25-hydroxyvitamin D.1,2 In fact, the biological activity of vitamin D3 is thought to be highly superior to that of vitamin D2. The most plausible explanation for this is that vitamin D3 binds more effectively to the body’s receptors.3
Holick et al. have nevertheless shown that if a supplement of 1,000 IU of vitamin D2 is administered each day, vitamin D2 is as effective as vitamin D3 at maintaining serum levels of 25-hydroxyvitamin D over a period of 11 weeks.4
Cholecalciferol and ergocalciferol
Cholecalciferol (vitamin D3) is a natural by-product of animal origin that is created from exposure to the sun, while ergocalciferol (vitamin D2) is a synthetic by-product of plant origin.
Studies have consistently shown that older adults who take 400 to 800 IU of vitamin D3 per day maintain their bone density and experience fewer fractures.5 The same cannot be said for vitamin D2.5
In addition to unequal bioavailability, vitamin D2 is also considerably less stable than vitamin D3, particularly when its crystalline powder is exposed to varying temperatures, humidity and even storage methods.5
References
- Armas LA et al. Vitamin D2 is much less effective than vitamin D3 in humans. J Clin Endocrinol Metab 2004;89:5387-5391.
- Trang HM et al. Evidence that vitamin D3 increases serum 25-hydr-oxyvitamin D more efficiently than does vitamin D2. Am J Clin Nutr 1998;68:854-858.
- Vieth R. What is the optimal vitamin D status for health? Prog Biophys Mol Biol 2006;92:26-32.
- Holick MF et al. Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. J Clin Endocrin Metab 2008;93(3):677-81.
- Houghton LA and Vieth R. The case against ergocalciferol (vitamin D2) as a vitamin supplement. Am J Clin Nutr 2006;84:694-697.
Keywords: vitamin D
Nutrients in Milk Products Keywords
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