Vitamin D3 vs D2: Which is Better?
Vitamin D3 is cholecalciferol, the natural form of vitamin D. It differs from vitamin D2 (ergocalciferol), which is synthesized by plants. Vitamin D helps maintain normal blood levels of calcium and phosphorus, leading to bone formation. Usage can help reduce the risk of bone loss, when taken with effective calcium, such as AdvaCAL long term.
According to WebMD:
“Currently, many major prescription forms of vitamin D are actually vitamin D2 and not vitamin D3. Vitamin D2 is synthetically made from radiating a compound (ergosterol) from the mold ergot. Vitamin D3 is made commercially and synthetically in a similar way that it is produced intrinsically in human and animal skin when exposed to UVB light. Wool sources of 7-dehydrocholesterol are used (from cholesterol), and irradiatied to form active vitamin D3. Vegetarians or especially vegans may be opposed to the use of vitamin D3 supplementation because it is derived from an animal source, and these individuals should be guided to the vitamin D2 form. Multivitamins have either vitamin D2 or D3”
Which is better: Vitamin D3 or D2? In an article entitled The case against ergocalciferol (vitamin D2) as a vitamin supplement (American Journal of Clinical Nutrition, Vol. 84, No. 4, 694-697, October 2006) Houghton and Veight note:
“Pharmacopoeias have officially regarded these 2 forms as equivalent and interchangeable, yet this presumption of equivalence is based on studies of rickets prevention in infants conducted 70 y ago. The emergence of 25-hydroxyvitamin D as a measure of vitamin D status provides an objective, quantitative measure of the biological response to vitamin D administration. As a result, vitamin D3 has proven to be the more potent form of vitamin D in all primate species, including humans…Vitamin D2, or ergocalciferol, should not be regarded as a nutrient suitable for supplementation or fortification.”
Similarly, an article published in the Journal of Clinical Endocrinolgical Metabolism [2004 Nov; 89(11):5387-91] noted that Vitamin D2 was only one-third as effective as vitamin D3 in humans:
“The relative potencies of vitamins D(2) and D(3) were evaluated by administering single doses of 50,000 IU of the respective calciferols to 20 healthy male volunteers, following the time course of serum vitamin D and 25-hydroxyvitamin D (25OHD) over a period of 28 d and measuring the area under the curve of the rise in 25OHD above baseline. The two calciferols produced similar rises in serum concentration of the administered vitamin, indicating equivalent absorption. Both produced similar initial rises in serum 25OHD over the first 3 d, but 25OHD continued to rise in the D(3)-treated subjects, peaking at 14 d, whereas serum 25OHD fell rapidly in the D(2)-treated subjects and was not different from baseline at 14 d. Area under the curve (AUC) to d 28 was 60.2 ng.d/ml (150.5 nmol.d/liter) for vitamin D(2) and 204.7 (511.8) for vitamin D(3) (P < 0.002). Calculated AUC(infinity) indicated an even greater differential, with the relative potencies for D(3):D(2) being 9.5:1. Vitamin D(2) potency is less than one third that of vitamin D(3). Physicians resorting to use of vitamin D(2) should be aware of its markedly lower potency and shorter duration of action relative to vitamin D(3).”
In sum, if you are a vegetarian, opt for vitamin D2. Otherwise, the research suggests that you will benefit as much as two times more from calcium supplements containing Vitamin D3.