Critically discuss issues with determining recommendations for vitamin Essay

Critically discuss issues with determining recommendations for vitamin D intake - Essay Example The proceeding process is their hydroxylation to form 25-hydroxyvitamin. The total of 25-hydroxyvitamin D2 together with 25-hydroxyvitamin D3 levels in serum is used as an indicator of vitamin D nutritional status. Studies indicate that this level increases following exposure to sunlight, or dietary intake of vitamin D (Rajakumar et al., 2014). 25-hydroxyvitamin D is hydroxylated to 1,25-dihydroxyvitamin D (calcitriol) in the kidney, a reaction catalyzed by 25-hydroxyvitamin D-1alpha-hydroxylase. Regulation of this reaction is by serum phosphorus, calcium, parathyroid hormone (PTH), fibroblast growth factor 23 and 1,25-dihydroxyvitamin. 1,25-dihydroxyvitamin D production has also been demonstrated in the skin, parathyroid gland, breast, colon, prostate, and immune system and bone cells. 1,25-dihydroxyvitamin D then binds to a receptor of vitamin D in the nucleus of a cell and recruits retinoic acid X receptor. This VDR/RXR complex binds small sequences of DNA called vitamin D response elements (VDREs) (Battault et al., 2013). It then initiates a cascade of molecular interactions that modulate the transcription of specific genes. Vitamin D regulates calcium and phosphorus homeostasis that are necessary for the maintenance of bone mineralization (Vieth, 2012). In the endocrine system Vitamin D regulates insulin secretion. Investigation shows that it is a potent immune system modulator. It also exhibits effects in the cardiovascular system regulating blood pressure. Severe vitamin D deficiency results in a condition known as rickets in children and osteomalacia in adults since it is important for development and maintenance of the bone structure (Persson et al., 2013). Osteoporosis has been linked to secondary hyperthyroidism caused by vitamin D deficiency. Increased PTH secretion by the parathyroid glands result in increased bone resorption increasing the bone breakdown and precipitate osteoporosis. Cancer,