Vitamin D is a fat-soluble vitamin that is naturally present in very few foods. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D formation. Its main biological function is to help the body utilise calcium which is necessary for the development and maintenance of strong bones and teeth.

In recent years doctors and scientists have reported that there has been an increase in the number of people who are reporting a deficiency in their body’s ability to produce vitamin D because of the high use of sunscreen and limited exposure to sunlight. Individuals with limited sun exposure (less than 1 hour direct sunlight per week) need to include sufficient amounts of good sources of vitamin D in their diet (e.g. eggs, oily fish and fortified margarines) or take a supplement. Vitamin D contributes to the maintenance of muscle function and the immune system.