Vitamin D was originally revealed as the active nutrient in cod liver oil that was used in the treatment of rickets and other disorders. It occurs in high amounts in cod liver oil and can be made by the body when exposed to ultraviolet light.
Vitamin D has several important functions and is essential for normal growth and development. Its mian function is the metabolism of calcium and phosphorus to support normal mineralisation (hardening) of bone. Vitamin D is involved in many aspects of calcium and phosphorus metabolism, including mediating intestinal absorption and utilisation.
Maintenance of the appropriate level of serum calcium is also necessary to promote proper functioning of the neuromuscular system and heart action. There is also some evidence that Vitamin D functions to improve muscle strength.
Deficiency signs of Vitamin D are characterised by inadequate mineralisation of bone and associated abnormalities such as soft bones, bowed legs, poor teeth and various skeletal deformities. In children, this can result in severe deformation of the skeleton (rickets). In adults, bone loss and an increased susceptibility to fractures can occur.
Eating foods such as salmon, tuna, flatfish, milk, cereal, pork, eggs, mushrooms, beef liver, ricotta cheese will help increase a person's Vitamin D levels. Consuming Vitamin D supplements together with these foods is a sure-fire way to meet the body's Recommended Daily Allowance (RDA).