A Clarification of Calcium Absorption and Vitamin D Effect on Osteoporosis

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Osteoporosis is a disease where the musculoskeletal system of the patient is affected. This disease is common among elderly people especially women past their menopause, and people who are inactive or sit for longer periods in chair or bed. It is mainly caused due to vitamin D deficiency. Vitamin D, which aids calcium absorption among other benefits to bone health, can be obtained from natural sources which are not enough to satisfy the body’s daily requirement. Therefore, vitamin D supplements are recommended to prevent osteoporosis and treat it.
The purpose of this essay is to clarify the relationship between calcium absorption and vitamin D essence for bone health with osteoporosis. Moreover, the essay will explain how to prevent and treat osteoporosis, and give an update of last researches in this field.
Firstly we need to define bone health. Bones are considered healthy when they are able to absorb enough amounts of nutrients. They tend to break due to several factors such as reduction of bone mass, changes of the bones distribution, and change in the bone material properties. These issues result in many illnesses such as osteoporosis (Mathers et al., 2009). Bone health can be influenced by the slightest changes in nutritional intake. For instance, “An increase in bone mineral density (BMD) by one standard deviation unit is likely to result in a 50% reduction in fracture rate” (Melton,1995 p.57).
In fact as we age our hormones tend to change and consequently our bone health is affected. For example, the BMD of postmenopausal women is weak due to the hormonal changes in their bodies. These changes affect calcium absorption, which in turn has a negative effect on bone health. Such effects can be avoided by increasing vitamin D intake (Mathers et al., 2009).
Secondly we need to define vitamin D which is one of the most important nutrients for people’s health. The vitamin is commonly defined as a group of fat-soluble pro-hormones that encourages the absorption and metabolism of calcium and phosphorous. Calcium is necessary for the prevention of bone diseases, cancer, diabetes and cardiovascular diseases (Holick, 2004A). Considering vitamin D chemical structure, Radlović et al. (2012) define it as “the precursor of the steroid hormone calcidiol [1,25-(OH)2 D] responsible for the homeostasis of calcium and phosphorous, as well as bone mineralization, and immune and hormonal regulation”.
Moreover, vitamin D chemical structure is represented by two major forms which are vitamin D2 and vitamin D3. While vitamin D2 can be found in ergocalciferol plants, vitamin D3 known as cholecalciferol is generated from (7-dehydrocholesterol) in the skin during exposure to sunlight. In the liver these precursors are converted to calcidiol (25-hydroxyvitamin D). Then calcidiol is transported to the kidney tubules where it is converted to Calcitriol (1,25-dihydroxyvitamin D).This process of vitamin D absorption in the body is illustrated in Figure 1. Calcitriol [1,25-(OH)2 D] is the active form of vitamin D that can provide the body with the vitamin biological functions (National Report on Biochemical Indicators, 1999-2000).
Our body’s requirement of vitamin D can be primarily satisfied from two natural sources which are food and sunlight. Foods that naturally contain vitamin D are oily fish such as salmon, mackerel and sardines. Examples of rich food sources are cod liver oil and mushrooms. In addition, egg yolks are reported to contain vitamin D, but considered as a poor source since its vitamin D content is highly variable and usually associated with cholesterol (Paul, 2012). Few foods are fortified with vitamin D such as milk, juice products, and some breads and cereals. Besides, vitamin D can also be obtained by exposing the skin to sunlight. Under normal conditions of sunlight exposure, no dietary supplementation is