Vitamin D is a vitamin that can be easily soluble in fat. It is vital for maintaining normal calcium metabolism. Humans can synthesize Vitamin D3 in their skin by exposing their skin to ultraviolet-B (UVB) radiation from the sun, or it can also be received from some of the diets. Plants synthesize vitamin D2 which is also having vitamin D activity in human beings. When exposure to UVB radiation is no sufficient for the synthesis of enough amounts of vitamin D3 in the skin, enough intake of vitamin D from the diet is very much required for health.
Benefits and Source of Vitamin D
Vitamin D is actually biologically inactive and it is made biologically active by some metabolic activities. After Vitamin D is consumed in the diet or it is synthesized in the skin then it enters the circulation and is subsequently transported to the liver. Vitamin D is hydroxylated in the lever to build 25-hydroxyvitamin D, the important circulating form of vitamin D. The increase in the intake of vitamin D and the increased exposure to sunlight increases serum levels of 25(OH) D, making the serum 25 (OH) D concentrations a vital indicator of vitamin D nutritional status. 25(OH) D3-1-hydroxylase enzyme catalyzes a second hydroxylation of 25(OH) D in the kidney and other tissues, thus leading to the formation of 1alpha, 25-dihydroxyvitamin D, which is the strong form of vitamin D. Almost all of the physiological effects of vitamin D in the body are associated with the activity of 1,25(OH)2D.
Importance of Vitamin D
Vitamin D plays a very important role in the proper maintenance of organ systems. Vitamin D determines the phosphorus and calcium levels in the blood by encouraging their absorption from food in the intestines and by encouraging the re-absorption of calcium in the kidneys. Vitamin D furthers mineralization and bone formation and is vital in the development of a strong and intact skeleton. It checks parathyroid hormone secretion from the parathyroid gland. The immune system of the body is affected by vitamin D by the promotion of immunosuppression, anti-tumor activity and phagocytosis. Vitamin D deficiency results from insufficient intake and inadequate exposure to sunlight, disorders that restrict its absorbing qualities, and some of the conditions which spoil the conversion of vitamin D into active metabolites, such as kidney or liver disorders, or some rare hereditary disorders. This deficiency ultimately results in spoilt bone mineralization and thus leads to some bone-softening diseases. Rickets in children and osteomalacia in adults are mainly due to the deficiency of vitamin D. Lack of Vitamin D may also be associated with various forms of cancer.
Breastfed babies are always at a much higher risk of having vitamin D deficiency, particularly if they have darker skin with little sun exposure. The milk of human beings provides 25 IU of vitamin D per liter and this is not enough for an infant if that is the only source of vitamin D. Infants who are older are fed with the substitutes of milk and weaning food. These foods do generally lack vitamin D and thus the risk of deficiency increases. Thus, it is necessary to have vitamin D in sufficient amounts to maintain a healthy body.
Read also: Vitamin C: Importance and Benefit