A fat-soluble vitamin, its deficiency can cause cancer, bone loss, and a weak immune system. It is a secosteroid, similar to steroids but with broken ring. Getting vitamin D is easy, just out of outside on a sunny day and viola, you have it. The skin converts from cholesterol to cholecalciferol. It is used in three forms, as supplements. Naturally, our skin converts it to D3 form i.e. cholecalciferol. While in the market you can find D2 i.e. ergocalciferol.
Vitamin D deficiency has been found to be the reason for many dangerous and life threatening diseases e.g. rickets, osteoporosis, arthritis, cancer.
Although its deficiency can cause disorders but if it exceeds optimum amount in the blood, it can accelerate the aging process.
Breastfed infants are required to take 400IU of Vitamin D. Older people need it more as their skin cannot convert it more efficiently because their kidneys are less able to convert into its more active form.
Calcium absorption requires Vitamin D. Higher calcium levels in blood are dangerous and also life threatening, so adequate intake of Vitamin D is a requirement when taking calcium supplements.
Vitamin D is good addition to your daily health maintenance. Stay healthy, Stay fit.