Litterature review on Vitamin D levels in infants in Afghanistan - Dissertation Example

Vitamin D deficiency is widespread with more than one billion people having insufficient circulatory levelsiv. Vitamin D is essential for maintaining adequate extracellular calcium and phosphate ion concentrations to enable normal mineralization of bone and prevent hypocalcemic tetany. It influences calcium levels throug promotion of its absorption in the intestine, through direct effects on bones and also through its effects on parathyroid hormone. It is also needed for bone remodeling and bone growth by osteoclasts and osteoblasts vvi.

If levels are low, hypovitamin D presents as a subclinical condition with latent manifestations of disease, bones can become thin, brittle, or misshapen. This often presents as rickets in children and osteomalacia in adultsvii. A high prevalence of childhood vitamin D deficiency exists in several developing countries (in such temperate regions similar in climate to Afghanistan) with abundant sunlight: Turkeyviii, Iranix, Saudi Arabiax, Indiaxi, Chinaxii, Mongoliaxiii, Algeriaxiv and Nigeriaxv.

The main source of vitamin D is obtained through Ultraviolet radiation on 7-dehydocholesterol in the skin. Small amounts can also be absorbed from dietary sources. It has been suggested that cultural practices, dark skin color, hot climates, lower calcium content in diets and lack of Vitamin D fortification in foods help explain the low vitamin D levelsxvi. In Afghanistan, exposure of women to sunlight is limited due to widespread use of Burqas. In children the extent to which they are covered and their exposure to sunshine and whether this correlates to vitamin D levels has not been investigated.

In our project, we propose to analyze the data obtained from a randomized control trial on an infant population in Kabul, Afghanistan. We will attempt to quantify the amount of sun exposure, analyze it in relation to various socioeconomic factors and try to establish – in children who live in these climates - whether there is an association with Vitamin D deficiency. The current adult recommendation for Vitamin D is 25-hydroxyvitamin D levels between 200 and 600 IU/d, but this level is currently controversial considering that a fifteen-minute whole-body exposure to summer sun will lead to 20,000 IU vitamin D-3 released into the body[1].

Optimal serum concentrations are variable based on study results, but one generally agreed-upon figured is approximately 75 nmol/l, although this varies according to individual characteristics [2]. Anther study suggests that an optimal level for adults is 25(OH)D ? 80 nmol or 32 µg/L, based on biomarkers that react to levels of vitamin D in the body[1]. Other studies agree with the figure of 75-80 nmol/L being required for optimal bone health, although this research was done in older white adults living in Europe and the United States and may therefore differ from levels in other racial and age groups [3].

Such results may not be applicable to the determination of healthy levels in children or in those of other racial groups such as the people in Afghanistan. These results may also be affected by the variation in diet between these cultures, as the United States and Europe encourage higher levels of calcium in the diet. There are also suggestions that the types of vitamin D that are obtained through oral ingestion are not metabolically identical to those obtained through cutaneous synthesis, which requires sun exposure [2].

There is a lack of current studies relating vitamin D levels to health in any group