Vitamin D: How Much You Need and Where to Get It
Adults and children over 1 need 10 micrograms (400 IU) of vitamin D a day, according to the NHS. Your skin makes it from sunlight in spring and summer, but few foods contain much, so many people are advised to take a 10 microgram supplement in autumn and winter, or all year if they get little sun.
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Key takeaways
- Vitamin D helps the body control calcium and phosphate, which keep bones, teeth and muscles healthy.
- Adults and children over 1 need 10 micrograms (400 IU) a day; babies need 8.5–10 micrograms.
- Good food sources include oily fish, egg yolks, red meat and fortified foods, but food alone rarely provides enough.
- Don't take more than 100 micrograms (4,000 IU) a day unless a doctor advises it.
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What vitamin D does
Vitamin D helps your body control the amount of calcium and phosphate it absorbs. Both are needed for healthy bones, teeth and muscles. A severe lack of vitamin D can cause bone deformities such as rickets in children, and bone pain from a condition called osteomalacia in adults.
How much vitamin D do you need?
| Who | Daily amount (NHS) |
|---|---|
| Babies up to 1 year | 8.5 to 10 micrograms |
| Children from 1 year and adults | 10 micrograms (400 IU) |
| Pregnant and breastfeeding women | 10 micrograms (400 IU) |
Units: 1 microgram (mcg or µg) = 40 IU. Labels may use either. Our unit converter handles common health units.
Sunlight: the main source for most people
Your skin makes vitamin D when it is exposed to direct sunlight outdoors. In the UK, the NHS says most people can make all they need from about late March or early April to the end of September. Between October and early March, the sun isn't strong enough there. How much you make anywhere depends on latitude, season, time of day, skin colour, clothing and time spent outside.
You don't need to sunbathe or burn to make vitamin D. Protect your skin when the UV index is high: see our guide to choosing and using sunscreen.
Food sources of vitamin D
Only a small number of foods contain vitamin D:
- oily fish such as salmon, sardines, trout, herring and mackerel
- red meat
- egg yolks
- fortified foods, such as some breakfast cereals and fat spreads
- liver (avoid liver during pregnancy)
Because these provide relatively little, it's hard to get enough vitamin D from food alone.
Should you take a vitamin D supplement?
UK government advice, summarised by the NHS:
- Everyone (including pregnant and breastfeeding women) should consider a daily 10 microgram supplement during autumn and winter.
- Take one all year if you're rarely outdoors, live in a care home, or usually cover most of your skin when outside.
- People with dark skin, for example of African, African-Caribbean or South Asian background, may not make enough vitamin D from sunlight and should consider a supplement all year.
- Children aged 1 to 4 should have a daily 10 microgram supplement all year. Babies who are breastfed, or who have less than 500 ml of infant formula a day, should have 8.5 to 10 micrograms a day.
Advice differs between countries, so check your local health service's guidance too.
Can you take too much?
Yes. Taking too many vitamin D supplements over a long time can cause too much calcium to build up in the body, which can weaken bones and damage the kidneys and heart. The NHS advises adults not to take more than 100 micrograms (4,000 IU) a day unless a doctor recommends it. Children's limits are lower. You can't overdose on vitamin D from sunlight.
When to see a doctor
See a doctor if you have bone pain, muscle weakness, or a condition or medicine that affects how you absorb vitamin D. A blood test can check your level. Don't take high-dose supplements without medical advice.
Common questions
How do I convert micrograms to IU for vitamin D?
1 microgram of vitamin D equals 40 IU. So 10 micrograms is 400 IU, and 100 micrograms is 4,000 IU.
Can I get enough vitamin D from a sunny window?
The body makes vitamin D from direct sunlight on the skin when you are outdoors. Glass blocks most of the UVB rays involved, so sitting behind a window is not a reliable source.
Does vitamin D prevent COVID-19?
The NHS states there is not enough evidence to support taking vitamin D solely to prevent or treat COVID-19.
