Vitamin D plays a critical function in helping to build and maintain strong and healthy bones as well as helping to ensure adequate bone density. Vitamin D is a unique vitamin in that it can be supplied in the diet and made in the body. Most vitamins are not made in the body and have to be supplied by the diet.
Supplies of vitamin D2 and vitamin D3 make up the body’s vitamin D supplies. Vitamin D2 is also known as ergocalciferol and can be supplied in milk, eggs, oily fish such as sardines, salmon, mackerel, tuna, cod, beef, liver, fortified breakfast cereals, fortified juices and vegetable oil spreads.
Vitamin D3, also known as cholecalciferol is produced in the skin after direct contact with sunlight. It is estimated that we can make up to 90% of our vitamin D from natural sunlight. Cholesterol stores in the skin convert the sunlight to vitamin D3 or cholecalciferol.