Most adults need 10 to 15 micrograms (400 to 600 IU) of vitamin D a day, depending on where you live: the NHS recommends 10 mcg, while the US recommendation is 15 mcg for most adults and 20 mcg over 70. Your skin makes vitamin D from sunlight, and a few foods provide it, mainly oily fish, egg yolks and fortified foods. In autumn and winter, or if you rarely go outdoors, it’s hard to get enough, which is why the NHS advises considering a daily 10 mcg supplement.
Why vitamin D matters
Vitamin D helps your body absorb calcium and phosphate, which keep bones, teeth and muscles healthy. A long-term lack can lead to bone problems such as rickets in children and osteomalacia (soft bones) in adults, as the NHS explains.
How much vitamin D you need
| Group | UK (NHS) | US (NIH) |
|---|---|---|
| Children from 1 year and adults | 10 mcg (400 IU) | 15 mcg (600 IU), ages 1 to 70 |
| Adults over 70 | 10 mcg (400 IU) | 20 mcg (800 IU) |
| Pregnancy and breastfeeding | 10 mcg (400 IU) | 15 mcg (600 IU) |
| Babies under 1 | 8.5 to 10 mcg if breastfed or on less than 500 ml of formula | 10 mcg (400 IU) |
Sources: the NHS and the NIH Office of Dietary Supplements. One microgram equals 40 IU.
Food sources of vitamin D
Few foods contain much vitamin D. Per 100 g, from USDA FoodData Central:
| Food (100 g) | Vitamin D |
|---|---|
| Mushrooms exposed to UV light | 26.2 mcg |
| Atlantic mackerel | 16.1 mcg |
| Rainbow trout, farmed | 15.9 mcg |
| Atlantic salmon, farmed | 11.0 mcg |
| Egg yolk | 5.4 mcg |
| Sardines, canned in oil | 4.8 mcg |
| Whole egg | 2.0 mcg |
| Milk with added vitamin D (US) | 1.3 mcg |
A portion of oily fish can provide a whole day’s vitamin D. Regular mushrooms contain very little, but mushrooms exposed to UV light during growing, which are sometimes sold specially labelled, contain much more. Fortification varies by country: the NHS notes that cows’ milk is generally not a good source in the UK, while milk is often fortified in the US and Canada. Check the label.
Vitamin D from sunlight
Your skin makes vitamin D when it’s exposed to direct sunlight outdoors. In the UK, the NHS says most people can make enough from late March or early April to the end of September. In winter, the sun isn’t strong enough at that latitude.
How much you make depends on where you live, the season, the time of day, your skin tone and how much skin is uncovered. Sunlight through a window doesn’t count. Never let your skin burn: the NHS advises covering up or protecting your skin before it starts to turn red or burn, to reduce the risk of skin damage and skin cancer.
Who should consider a vitamin D supplement?
The NHS advises:
- Everyone in the UK should consider taking 10 mcg a day during autumn and winter.
- All year round for people who rarely go outdoors, such as frail or housebound people and those in care homes, and for people who usually wear clothes that cover most of their skin when outdoors.
- People with dark skin, such as those of African, African-Caribbean or South Asian background, may also not get enough from sunlight and should consider a supplement all year.
- Babies who are breastfed, or have less than 500 ml of infant formula a day, should have a daily supplement of 8.5 to 10 mcg from birth.
If you live elsewhere, the same principles apply. People far from the equator, or who get little sun, are more likely to need a supplement. Ask your doctor or pharmacist what’s right for you.
Can you take too much?
Yes. The NHS says not to take more than 100 mcg (4,000 IU) a day as an adult or child aged 11 to 17, 50 mcg for children aged 1 to 10, and 25 mcg for babies under 12 months. Taking too much for a long time can cause calcium to build up in the body (hypercalcemia), which can weaken bones and damage the kidneys and heart.
You can’t get too much vitamin D from sunlight. The risk comes from high-dose supplements, especially when several products containing vitamin D are taken together. Some people with medical conditions need a lower dose, so check with your doctor.
Vitamin D and vegan diets
Some vitamin D supplements come from animal sources. The NHS advises vegans to read the label to make sure the vitamin D isn’t of animal origin. Our beginner’s guide to a vegan diet covers the other nutrients to plan for.
Easy ways to get more vitamin D from food
- Eat oily fish once or twice a week, such as salmon, mackerel, trout or sardines. Our guide to omega-3 foods lists the best options.
- Include eggs, with the yolk.
- Choose fortified foods such as some breakfast cereals, spreads and plant drinks.
- Look for UV-exposed mushrooms if you can find them.
- Get outdoors in daylight when the season allows, without letting your skin burn.
Common questions
Is it better to take vitamin D2 or D3?
Both forms are used in supplements and fortified foods. Many supplements contain vitamin D3. If you’re vegan, check the source, because D3 is often made from animal products, while D2 and some D3 products are plant-based. Ask your pharmacist if you’re unsure.
Should I get my vitamin D level tested?
Most people don’t need a test. Your doctor may suggest one if you have symptoms such as bone pain or muscle weakness, a condition that affects absorption, or a high risk of deficiency.
Does sunscreen stop vitamin D production?
Sunscreen reduces the sun’s effect on your skin, but the NHS still advises protecting your skin before it burns. Following that advice and taking a supplement in winter is the safe approach.
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
