Vitamin D Deficiency in the UK: Causes, Risk Factors and Prevention

Low vitamin DClinical is common in the UK, largely because of latitude. Between October and early March, UK sunlight does not contain enough UVB for the skin to make vitamin DClinical, so intake depends on diet and supplements. Public-health guidance therefore advises a daily 10 microgram (400 IU) supplement in autumn and winter, and all year for some groups.

Why the UK is different

The UK sits between roughly 50 and 60 degrees north. At that latitude the sun does not rise high enough in winter for meaningful UVB to reach ground level. A bright, cold January day produces no vitamin D. Behaviour matters too: indoor work, screen time, air pollution and correct sun-safety habits all reduce skin synthesis.

Who is at greater risk

UK guidance identifies groups advised to take a daily supplement throughout the year:

• people who are rarely outdoors, including those who are housebound or living in a care home
• people who usually wear clothing that covers most of the skin when outdoors
• people with dark skin, including those of African, African-Caribbean and South Asian family background, because more melanin reduces skin synthesis
• infants and young children under 5, and pregnant or breastfeeding women, following NHS Healthy Start guidance

Additional clinical risk factors include malabsorption conditions such as coeliac disease, Crohn's disease and cystic fibrosis, previous bariatric surgery, chronic liver or kidney disease, obesity, and long-term use of certain medicines including some anticonvulsants and glucocorticoids.

What prevention looks like in practice

• Autumn and winter: consider a daily supplement providing 10 micrograms (400 IU) if you are aged 1 or over.
• Spring and summer: most people make enough from short periods of daily sunlight on the skin, without letting the skin redden or burn.
• All year, if you are in an at-risk group: take the daily supplement year-round.
• Babies under 1: 8.5 to 10 micrograms daily, unless they have more than 500 ml of infant formula a day, which is already fortified.
• Diet: include oily fish, eggs, and fortified foods regularly. See vitamin D foods.

Healthy Start and free vitamins

Some families in England, Wales and Northern Ireland qualify for free Healthy Start vitamins containing vitamin DClinical for pregnant women and young children. Scotland offers free vitamin DClinical supplements to pregnant and breastfeeding women and children under 3 through its own scheme. Ask your midwife, health visitor or pharmacist.

Public-health advice is not individual advice

The 10 microgram figure is a population-level recommendation designed to cover most people's needs. It is not a treatment for diagnosed deficiency, which is managed by a clinician with higher, time-limited doses and appropriate follow-up. If you think you may be deficient, speak to your GP rather than escalating the dose yourself.

Related reading

• Vitamin D: a UK evidence-based guide
• Vitamin D in winter
• How much vitamin D do you need?
• Vitamin D deficiency symptoms

References and further reading

• Vitamin D — NHS. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ (accessed 26 August 2026)
• SACN vitamin D and health report — GOV.UK. https://www.gov.uk/government/publications/sacn-vitamin-d-and-health-report (accessed 26 August 2026)
• Vitamin D: advice for all age groups — GOV.UK. https://www.gov.uk/government/publications/vitamin-d-advice-on-supplements-for-at-risk-groups (accessed 26 August 2026)
• Healthy Start — NHS. https://www.healthystart.nhs.uk/ (accessed 26 August 2026)