Most of the body's vitamin D is formed when the skin is exposed to UVB radiation. Many people suffer from a vitamin D deficiency in the winter because they spend all day indoors and the mornings and evenings are dark. The initial symptoms of vitamin D deficiency are tiredness and an inability to concentrate, but muscle weakness and depression can also develop over the long term. Since vitamin D is essential for the development of healthy bones, it is especially important to recognise the symptoms in children at an early stage or, better still, prevent their development in the first place.
A small amount of vitamin D is absorbed through normal nutrition (principally from oily fish such as eels, herring or mackerel) and is also present in egg yolk, milk, butter and meat. However, it is not possible to absorb enough vitamin D through food alone. As a result many people resort to dietary supplements in the form capsules or drops during the winter months. This cannot, however, be recommended because there is always the risk of an overdose. A doctor can conduct a test to see if an individual has a vitamin D deficiency and, where necessary, prescribe a remedy. However, many experts only recommend supplements for people who never go out of doors or suffer from a severe deficiency. Studies have also shown that there is no evidence to suggest that supplements increase bone density or prevent breaks. Equally, there is no evidence that they offer protection against infections, cancer or diabetes.
The good thing about vitamin D is that you can build up your body's supplies during the summer. However, you should also be careful to protect your skin against harmful UVB rays. Sunbeds are not recommended, primarily because experts cannot agree on whether they increase the risk of skin cancer. It is also a good idea in the winter to go outdoors for around 20 minutes a day.
The best way of building up vitamin D reserves, of course, would be a short break in a sunny climate, but since this isn't always possible for reasons of time or money, we have put together some tips to help you spend more time out of doors in your everyday life and so boost your vitamin D production: