The Vitamin D also called as 1,25 dihydroxyl vitamin D is produced by your kidneys is a major steroid hormone used for mineral ions regulation in the body.On exposure to sunlight 7-dehydrcholestrol from the skin is activated ny the UV rays to form the vitamin D.
Vitamin D production is decreased by sunblocks as it prevents UV rays to seep through.
Also in North America and Western Europe due to reduction of magnitude of solar exposure vitamin D supplementation through diet is advised.
These sources are cereals,dairy products accompanied by fish oils and egg yolks.
Plant sources produce Vit D2 and Vit D3 which is equally biological active.
The safety margin for vitamin D supplementation is large Vitamin D toxicity is caused by taking 40,000 IU, and in adults Vitamin D deficency leads to formation of spongy bone syndrome called osteomalacia,
Thus for treatment of Vit D deficency
800 IU of Vitamin D with Calcium supplementation is essential.
This was found to reduce the risk of hip fractures in elderly women and also to prevent Vit D deficency in adults.
Calcium is important as most of the times Vit D deficnecy results due to impaired mineral ion hemostasis.
The Vit D deficency is more common with old age as person's ability to produce Vit D declines.