Vitamin D3 (25-OH D3)

25-hydroxyvitamin D3 [25(OH)D3] is the measured form of Vitamin D3 (Cholecalciferol), synthesized in the skin upon sun exposure and found in animal-based foods and most supplements. It is generally considered more effective at raising and maintaining total 25(OH)D levels than D2. The sum of 25(OH)D2 and 25(OH)D3 constitutes the total Vitamin D status [Total 25(OH)D]. Measuring D3 specifically is usually not necessary if Total 25(OH)D is measured.