METABOLISM

Synthesis of Vitamin D (Cholecalciferol)

In the presence of ultraviolet (UV) light from the sun, 7-Dehydrocholesterol is converted into vitamin D. Vitamin D circulates in the blood and is used in the mineralisation of bone, along with calcium and phosphate. It is also thought to be important for muscles and general health and may also help prevent other diseases such as cancer, diabetes, and heart disease (Tortora & Derrickson, 2013).

The major cause of vitamin D deficiency is the lack of appreciation that sun exposure in moderation is the major source of vitamin D for most humans (Mostafa & Hegazy, 2015). It is recommended that 2-3 exposures of sunlight per week in the summer months (April to September) are enough to achieve healthy Vitamin D levels that last throughout the year. Each episode of exposure should be no more than 20-30 minutes. Over-exposure should be avoided as this may lead to sunburn and an increased risk of skin cancer.

Elderly people who have thinner skin are also at risk, as they are unable to produce as much vitamin D; additionally certain medical conditions such as Crohn’s disease, celiac disease and some types of liver and kidney disease are at risk of vitamin D deficiency.