What is Vitamin D and Its Effects on Bone?
Vitamin D, or the “sunshine” vitamin, is a fat-soluble vitamin that plays a key role several functions of the body. Calcium metabolism, phosphorus homeostasis, muscle function, and cell: differentiation, proliferation, and growth all rely on vitamin D to perform their jobs efficiently (Gropper et al. 2013). The main focus of this paper is to discuss how vitamin D is made and the effect it has on bone, including how vitamin D deficiencies or insufficiencies can lead to many problems with calcium metabolism, and in turn lead to diseases associated with weakening of bones.
Vitamin D comes from three sources, sunlight, the diet, and dietary supplements. For almost all people the main source for making Vitamin D is through direct exposure to sunlight. Many factors can affect how vitamin D is synthesized through the skin; things like season (winter, etc.), time of day, length of day, cloud cover, smog, amount of skin melanin, and sunscreen all affect one’s ability to gain enough exposure to the ultraviolet (UV) radiation that is needed for Vitamin D to synthesize (Holick 2006).
The other way Vitamin D enters the body is through food sources in the diet. Fatty fish (like tuna, salmon, and mackerel) are great sources, while foods like beef liver, cheese, and egg yolks offer less. There are few foods that naturally have vitamin D in them; a lot of foods are fortified with vitamin D. About 400 IU of vitamin D per quart are added to most of the milk in the United States, although most foods that milk plays apart in making are usually not fortified. Breakfast cereals, many brands of orange juice, yogurt, and margarine are also fortified with Vitamin D in the United States (“The Truth About Vitamin D”, 2009).
Receiving enough vitamin D can be difficult for some people. Vitamin D supplements may be needed to reach the recommend amounts of Vitamin D the body needs to perform efficiently. Supplements are available in two forms...