1 Introduction Vitamin D is a fat-soluble vitamin that is essential for bone health. Vitamin D can be obtained from various sources such as ultraviolet-B (UVB) radiation from sun exposure, dietary intake of foods that contain vitamin D (e.g., fish, eggs, and meat), and supplements (1, 2). There are two major forms of vitamin D, vitamin D3 (cholecalciferol), which can be obtained via sun exposure and dietary sources, and vitamin D2 (ergocalciferol), obtained from dietary sources.
