Vitamin D

Vitamin D helps regulate the amount of calcium and phosphate in the body. These nutrients are needed to keep bones, teeth and muscles healthy. Vitamin D deficiency occurs when the body doesn’t get enough vitamin D from sunlight or diet. Vitamin D deficiency can cause loss of bone density, osteoporosis, broken bones and rickets in children.

Vitamin D is sometimes called the sunshine vitamin because your body makes it from cholesterol when your body is exposed to sunlight. During the autumn and winter, you need to get vitamin D from your diet because the sun is not strong enough for the body to make vitamin D.

But since it's difficult for people to get enough vitamin D from food alone, the NHS recommends everyone (including pregnant and breastfeeding women) should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter.

Between late March to the end of September, most people can make all the vitamin D they need through sunlight on their skin and from a balanced diet.

Before your body can use vitamin D, your liver must change it into another form called 25 hydroxyvitamin D, or 25(OH)D. The Vitamin D Test measures the level of 25(OH)D in your blood in order to determine whether your body has deficient, insufficient, sufficient or excess levels of vitamin D in your blood to enable/prevent your body from working well.