Vitamin D is one of the fat soluble vitamins. Within the body vitamin D is converted into its active form which has been called calcitriol. Calcitriol promotes absorption of calcium from the intestine and thus vitamin D is concerned with the maintenance of bone health. Bone is formed as a result of deposition of calcium and phosphorus. Recently, other reports have come in suggesting that vitamin D can protect against the onset of several diseases. For a long time, it has been widely reported that exposure to the sun can cause skin cancer. In fact, it is this fallacy which has resulted in widespread vitamin D deficiency in several countries because people have shunned sunlight. Recently, scientists have admitted that exposure to sunlight can actually prevent skin cancer.
Yet another report suggests that vitamin D can counter some of the ill effects arising out of radiation exposure. This is achieved through the manipulation of the regulation of the cell cycle and the proliferation of the cells. Other events influenced by vitamin D during radiation exposure include cell differentiation and communication between cells. Vitamin D also promotes apoptosis (programmed cell death). Another mode of action involves prevention of new angiogenesis (new blood vessel formation), a process essential for the growth of tumor cells. Inhibition of new blood vessel formation is important because tumor cells are similar to normal cells in many respects and also have to be supplied with nutrients and oxygen.
Smooth flow of blood is essential for normal health because it is through the blood that many important fuel molecules and oxygen are supplied. Sometimes the blood vessels may become hard either, as a result of ageing or, due to other factors. Thus, the blood vessels tend to lose their elasticity and the flow of blood through the blood vessels becomes difficult. Thus, the heart has to increase the cardiac output and this may result in hypertension. Vitamin D supplementation greatly improves the vascular health and this, in turn, may keep the blood pressure under check.
Vitamin D is also cardioprotective. This is achieved in several ways. It prevents the uptake of cholesterol by the macrophages. It is the cholesterol which is present in the macrophages which is most suitable for plaque formation. It prevents the vascular smooth muscle growth. Calcification is a process which involves deposition of calcium in the arteries and is one of the processes which may be responsible for the hardening of the arteries and this process is also countered by vitamin D. Vitamin D also increases the anti inflammatory defenses.