Vitamin D is an important vitamin, which enables the absorption of calcium from the intestines into the blood. Vitamin D also allows calcium to be incorporated into our bones, and is therefore an important factor in maintaining healthy bones.The level of vitamin D mainly depends on our exposure to sun, as well as our diet.
Ultraviolet B (UVB) rays in sunlight converts cholesterol in the skin into vitamin D. For a fair-skinned person, it is estimated that around 20-30 minutes of sunlight on the face and forearms around the middle of the day 2-3 times a week is sufficient to make enough vitamin D in the summer months in the UK. However, for people with darker skin and the elderly, the amount of time needed exposed to sunlight to make enough vitamin D can be much more than this.
For six months of the year (October to April), much of Western Europe (including 90% of the UK) lies too far north to have enough UVB rays in sunlight necessary to make vitamin D in the skin. Many people in the UK are at risk of not getting enough vitamin D unless they get it in their diet.