Definition of Vitamin D
Vitamin D is a naturally occurring fat-soluble vitamin in very few foods, added to others, and accessible as a dietary supplement. It is also endogenously generated when sunlight ultraviolet rays hit the skin and cause the synthesis of vitamin D. This vitamin derived from exposure to the sun, food, and supplements are biologically inert and have to undergo two activation hydroxylations in the body. The first takes place in the liver, converting vitamin D to 25-hydroxyvitamin D[ 25(OH)D], also known as calcidiol.
- Vitamin D controls the concentrations of calcium and phosphorus in the blood by encouraging the absorption of calcium from food in the intestines and reabsorption of calcium in the kidneys.
- It encourages the bone formation and mineralization and is vital for an intact and powerful skeleton to be developed.
- It inhibits the secretion of the parathyroid hormone from the gland.
By encouraging immunosuppression, phagocytosis, and anti-tumor activity, vitamin D impacts the immune system.
Hormone for Calcium and Phosphate regulation
Calcium is essential for transmissions of nerve cells and contractions of muscle fiber.
Calcitriol works in conjunction with parathyroid hormone (PTH) and calcitonin to control the calcium and phosphorus concentrations of the serum by:
- Increasing the absorption of calcium from the small intestine by diet.
- Decreasing excretion of urinary calcium (increasing reabsorption of the kidney).
- Stimulates calcium resorption from the bone
Instrumental in bone growth, hardness, and repair. However, too much vit. D can boost bone calcium losses It is vital for ordinary pancreatic insulin secretion and therefore blood sugar levels to be controlled.
When vitamin D goes abnormal
- Too little leads to Vit D deficiency:
–Rickets (bone deformities in children)
–Osteomalacia (weak bones)
–Demineralization of bones
- Too much (5 times the RDA, chronically): It is the most toxic of the vitamins.
–Nausea, thirst, loss of appetite, stupor.
–Hypocalcemia: calcium gets deposited in soft tissues, arteries, and kidneys.
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