Vitamin D is an essential vitamin that your body makes in your skin from sunlight. Unfortunately, if you live in the UK, you almost certainly don't get enough sunlight throughout the year to make the vitamin D you need. This is why vitamin D deficiency is the commonest vitamin deficiency in the UK and we're all at risk.

Vitamin D is important for your bone health and for a strong immune system. Most people who are vitamin D deficient won't have any symptoms or will just feel run-down or a bit "off". You might also notice that you're always getting colds or other infections.

This simple blood test will give you your vitamin D level so you can see if you're deficient or not in the optimal range. You'll know if you need to be taking vitamin D supplements and can check again to make sure your supplements are getting your levels up to where they need to be.