In a tropical country like India, Vitamin D deficiency may not have a critical dimension because it is supposed to be produced in adequate amounts in the skin by exposure to sun light, especially during the period 10 am to 3 pm. 7 dehydrocholesterol present in vertebrates is converted to Viamin D by the Ultraviolet B rays in the wave length range between 290 and 320 nm. The two physiologically active forms of this vitamin, Ergocalcferol (D2) and Cholecalciferol (D3) are necessary for many body functions though lot remains to be discovered regarding their role fully. Liver and Kidney convert the vitamin into biologically active molecule 25 hydroxy D (Calcidiol) and then to 1,25 hydroxy D (Calcitriol), the latter having a half life span of 15 hours in the blood. One of the major roles of Vit D is in bone mineralization which has been well studied. Deficiency of Vit D is manifested in childhood as Ricket while in adults it is osteomalacia. Weak, brittle and misshapened bones are attributed to Vit D defiency.Vit D is also involved in some immune functions when Calcitriol is made in monocute-macrophages in the immune system and it acts more or less as a cytokine defending the body against microbial invaders.
While the importance of Vit D to bone health has been scientifically understood since the 17th century, an area not well documented is its relation to heart health. According to one survey in USA, more than 40 percent of men and 50 percent of women have low Vit D levels and they are considered to be more vulnerable to coronary artery disease and heart failure. Other studies with European population have shown that they have low Vit D levels while in many northern hemisphere countries, Vit D deficiency seems to have reached nearly epidemic proportions. Vit D helps prevent high blood pressure, suppresses inflammation by protecting the cells that line the blood vessels and maintains blood-vessel flexibility. Analysis of data from some of the studies concerning connection between heart and Vit D has brought out that low levels of this vitamin make the heart work harder, establishing its role in protecting against cardiovascular disease. Vit D supplements, about 1000 IU a day, have also been suggested to provide protection to the heart and prevent the risk of congestive heart failure, especially amongst vulnerable and old age population.
While the precise mechanism as to how Vit D is involved in heart disease is not yet known, there are indications that it has some thing to do with atherosclerosis and plaque development. As Vit D plays an active role in mineralization of bone through activation and incorporation of Calcium into the bone matrix and Calcium blockers are routinely used for treating heart patients, plaque formation in arteries may possibly be influenced by Vit D levels in the blood. What is intriguing is that how both deficiency and excess of Vit D can contribute to plaque development, indicating much more needs to be known before coming to any conclusion. The reported high incidence of Ischemic Heart Disease in southern parts of India has been attributed to excess Vit D production in the body. Vit D deficiency is also implicated in Peripheral Arterial Disease and here again nothing much is known about the reason.
Vit D deficiency seems to have some connection with diabetes according to scientists at Johns Hopkins University School of Medicine who noted that poor diabetes control in many subjects is invariably associated with Vitamin D deficiency. It is too premature to establish a cause-effect relationship but the fact still remains that higher the HbA1c value greater was the deficiency of Vit D. According to the most recent research, most people who live in the northern hemisphere, especially people over 50 and those who are overweight, may be benefited by Vitamin D supplementation. Though the current official recommendation is 400 IU for ages 51 to 70 and 600 IU for those over 71, there appears to be a tacit recognition that taking about1,000 to 4,000 IU per day could be more beneficial for such people. Between Vitamin D2 and D3, latter seems to be three times more effective in raising the vitamin level in the blood. Fatty fish, eggs and meat are reasonably good sources of Vit D but probably their regular consumption may not be adequate for meeting fully the body's need for this nutrient. U V irradiated mushrooms are now being offered in health stores as they contain good levels of Vit D formed from the natural Ergosterols present in this edible fungi.
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