The main function of vitamin D is to help the body absorb calcium for strong teeth and bones.
Vitamin D comes from the sun, so we get some vitamin D every day from our skin's exposure to sunlight.
However, this can be a problem for some people. Groups at risk include older adults, those who are house-bound, those who follow religions where the skin should be covered and those who work long hours indoors.
Therefore, it is important that we get some vitamin D from our diet. It can be obtained from the following sources:
There are two conditions that can occur as a result of a lack of vitamin D in the diet.
In children a deficiency of vitamin D is called rickets – a condition affecting bone development that can lead to deformity of the skeleton.
In adults, this is called osteomalacia – a very painful condition caused by the bones being weak, or 'soft'.