Vitamin D and Bone Health
The importance of bones is often underestimated until we are faced with a serious health concern that impairs our ability to function. We tend to forget about bone health because it is beneath the surface and often masked by other health concerns which have more apparent symptoms than that of bone degeneration. Often times bone degeneration disorders, like osteoporosis, are not diagnosed until later in life when symptoms become largely apparent. By the time osteo disorders are diagnosed, prevention may not be as much an option as maintaining what existing bone structure is left. Bones make up our skeleton and give us a backbone, pun intended. Our bones are an organ system not to be forgotten.
Osteoporosis is defined as a bone degenerative disorder resulting in a loss of bone mass that occurs in 55% of adults in the United States. Of these, most are predominately women (Nieves, 2005). Osteoporotic fractures are one of the leading and most costly indications for this disorder. Nutrition can play a significant role in the prevention of osteoporosis and the overall health of our bones, although it is widely ignored. When we do think of the role nutrition can play on bone health, one of the first thought that pops into your mind is calcium and calcium rich foods. Even better, I'm sure we all get the vision of a milk mustache and the infamous quote: "Got Milk?" Although calcium is essential for bone health, it wouldn't be as effective without the help of vitamin D.
Vitamin D is considered the "sunshine vitamin" due to the body's ability to synthesis vitamin D when exposed to direct sun light. Very little foods contain a sufficient amount of vitamin D to fulfill our body's needs. As a matter of fact, most foods that do contain vitamin D are considered fortified, which means added to increase nutrient value. The only food sources that provide a vitamin D to the body includes oily fish such as salmon, mackerel, and sardines. Some research indicates wild caught salmon to have approximately 400-600 IU per serving (Zhang & Naughton, 2010). How does basking in the rays of the sun and eating fish help in bone health? In short, vitamin D helps increase the absorption of calcium for our body. Without it we would not be able to optimally absorb and utilize calcium for our bones as we do.
Bones are a beautiful organ system which is constantly breaking down and rebuilding to maintain strong healthy structure. The problem with bone health occurs when the break down exceeds the amount of bone that is being rebuilt in the constant remodeling process. Although calcium plays a critical role in the rebuilding phase of bones, our bodies need vitamin D to sufficiently absorb calcium. When we are exposed to sunlight or dietary vitamin D, our liver is responsible for processing it to calcidiol, which is the form of vitamin D that is most plentiful and utilized by our body. Without adequate vitamin D, only about 16% of the calcium we consume is absorbed (Zhang & Naughton, 2010).. The current recommended daily allowance of vitamin D intake for adults over the age of 50 is 400 IU daily, and increasing to 600 IU for elderly over 75 (Nieves, 2005). It has been further studied that there can be benefit to additional intake up to 1000 IU daily, especially for those that live further north and have very little sunshine (Nieves, 2005).
There has been little contraindications reported with vitamin D intake. As a matter of fact, toxification from vitamin D is considered rare. (Zhang & Naughton, 2010). The sunshine vitamin is used for many other health benefits that it is more common to be deficient than to exceed RDA. Making sure we have strong bones require multiple factors from other nutrients, like calcium and phosphorus, to exercise and lifestyle. The beginning of bone health though starts with vitamin D.
References
Nieves, J.W. (2005). Osteoporosis: the role of micronutrients. The American Journal of Clinical Nutrition, 81(5). https://doi.org/10.1093/ajcn/81.5.1232
Links to an external site.
Price, C. T., Langford, J. R., & Liporace, F. A. (2012). Essential Nutrients for Bone Health and a Review of their Availability in the Average North American Diet. The Open Orthopaedics Journal, 6, 143–149. http://doi.org/10.2174/1874325001206010143
Zhang, R. & Naughton, D.P. (2010). Vitamin D in health and disease: Current perspectives. Nutrition Journal, 9(65). https://doi.org/10.1186/1475-2891-9-65