Vitamin D helps the body absorb calcium and keep bones, teeth and muscles healthy. Most of it is made in the skin from sunlight — which is in short supply in the UK for part of the year.
The UK advice
Between October and early March, sunlight in the UK isn't strong enough for the skin to make vitamin D. The NHS advises everyone to consider a daily supplement of 10 micrograms (400 IU) during autumn and winter.
Who should consider it all year
- People who are rarely outdoors, such as those who are housebound or in care homes.
- People who cover most of their skin when outside.
- People with dark skin, such as those of African, African-Caribbean or South Asian origin, who may not make enough even in summer.
- Babies and young children (specific doses apply — see NHS guidance).
Food sources
Few foods are naturally rich in vitamin D: oily fish (salmon, sardines, mackerel), red meat, liver and egg yolks. Some breakfast cereals, fat spreads and plant milks are fortified. It's hard to get enough from food alone.
Don't overdo it
Taking too much over a long period can be harmful. Adults shouldn't exceed 100 micrograms (4,000 IU) a day unless advised by a doctor.