What are the different types of vitamin D?

Vitamin D is a fat soluble vitamin that naturally occurs in some foods, is added to others during production and is available as a dietary supplement.

The majority your body’s vitamin D is manufactured by your own body, in the skin during sunlight exposure.1 It plays an important role in normal bone development and maintenance, through the regulation of calcium and phosphorous levels. Vitamin D is also necessary for proper functioning of the immune system, hormones and cardiovascular health.2

Vitamin D is naturally found in only a few foods. These include fatty fish such as mackerel, salmon and sardines, fish liver oils and eggs. Other foods may contain vitamin D that has been added during the manufacturing process, such as some milks and infant formulas, orange juice, cereals and breads.2 Current patterns of eating and food supplies mean that it is almost impossible to consume enough vitamin D from your diet alone.3

The term ‘vitamin D’ refers to not one, but several different forms of the vitamin. Two forms are important in humans: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 is synthesized by plants, whereas Vitamin D3 is the form synthesized in your skin in the presence of ultraviolet B (UVB) rays.4 Both Vitamin D2 and Vitamin D3 are biologically inactive forms of Vitamin D. Before they can become active in your body, they must be converted to active forms in the liver and kidneys.2

Vitamin D supplements may contain vitamins D2 or D3. Vitamin D2 is derived from fungus or yeast. It was first produced in the 1920’s by exposing foods to ultraviolet light. This process was then patented, and licensed to pharmaceutical companies. Vitamin D3 is made in a similar way to how it is naturally produced in the skin of humans and animals. It is usually sourced from lanolin in sheep’s wool.5