Vitamin D has a number of important functions; it helps regulate the amount of calcium and phosphate in the body, both of which are needed to help keep bones and teeth healthy.

Vitamin D is a fat-soluble vitamin so you don’t need it every day – any of the vitamin your body doesn’t need immediately is stored for future use.

It is found in a small number of foods. Good food sources are oily fish and eggs but also include  fortified foods such as margarine, breakfast cereals and powdered milk. However, we get most of our vitamin D from sunlight on our skin. This is because the vitamin forms under the skin in reaction to sunlight. The best source is summer sunlight but remember, if you’re out in the sun, take care not to burn.

Most people should be able to get all the vitamin D they need from their diet and by getting a little sun. However, if you are pregnant or breastfeeding you should take 10 micrograms of vitamin D each day.

You might be particularly short of vitamin D, and so might want to think about taking 10 micrograms (0.01 mg) of vitamin D each day, if you: