Vitamin D helps regulate the amount of calcium and phosphate in the body.
These nutrients are needed to keep bones, teeth and muscles healthy.
A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain caused by a condition called osteomalacia in adults.
Government advice is that everyone should consider taking a daily vitamin D supplement during the autumn and winter.
People at high risk of not getting enough vitamin D, all children aged 1 to 4, and all babies (unless they’re having more than 500ml of infant formula a day) should take a daily supplement throughout the year.
Some people will not make enough vitamin D from sunlight because they have very little or no sunshine exposure.
The Department of Health and Social Care recommends that adults and children over 4 take a daily supplement containing 10 micrograms of vitamin D throughout the year if they:
are not often outdoors – for example, if they’re frail or housebound
are in an institution like a care home
usually wear clothes that cover up most of their skin when outdoors