Sunlight
Our bodies can produce vitamin D when our skin is exposed to sunlight.
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Vitamin D Explained Simply
Why vitamin D matters, where it comes from and why some people may be at greater risk of deficiency.
01
Why do we need vitamin D?
Vitamin D helps the body absorb calcium and supports healthy bones, teeth and muscles. It also has roles in normal nerve, muscle and immune function.
Unlike most nutrients, our bodies can make vitamin D when our skin is exposed to sunlight.
02
Where does vitamin D come from?
Food
Vitamin D is naturally present in a limited number of foods. Sources include oily fish such as salmon, sardines and mackerel, egg yolks and some fortified foods.
Supplements
Because it can be difficult to obtain enough vitamin D from food alone, official guidance in some countries recommends vitamin D supplements for certain people or at certain times of year.
03 · Important context
Vitamin D and darker skin
Melanin, the pigment that gives skin its colour, reduces the skin's ability to produce vitamin D from sunlight.
In the UK, official guidance identifies people with darker skin, including people of South Asian, African and African-Caribbean backgrounds, as being at increased risk of not getting enough vitamin D from sunlight.
UK guidance advises these groups to consider taking a daily vitamin D supplement throughout the year.
This may be particularly relevant to South Asian families living in countries with limited sunlight during parts of the year.
04
How much vitamin D do adults need?
UK guidance
Adults should aim for 10 micrograms (400 IU) of vitamin D per day.
UK guidance advises everyone to consider taking a daily 10 microgram (400 IU) vitamin D supplement during autumn and winter.
People at increased risk of deficiency, including people with darker skin such as those of South Asian origin, should consider taking 10 micrograms (400 IU) throughout the year.
US guidance
The US recommended dietary allowance for adults aged 19–70 is:
15 micrograms (600 IU) per day.
For adults aged 71 and over:
20 micrograms (800 IU) per day.
Recommendations vary between countries. These figures refer to general population guidance rather than treatment of diagnosed vitamin D deficiency.
05
Can you get vitamin D from food?
Food can contribute to your vitamin D intake, but relatively few foods naturally contain substantial amounts.
- ✓ Oily fish such as salmon, sardines and mackerel
- ✓ Egg yolks
- ✓ Some fortified breakfast cereals
- ✓ Fortified foods and drinks
- ✓ Some meat and other animal products
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Who may be at greater risk of not getting enough vitamin D?
- ✓ People with darker skin
- ✓ People who spend little time outdoors
- ✓ People who cover most of their skin when outdoors
- ✓ People living in places where sunlight is limited during parts of the year
Do not diagnose vitamin D deficiency based on these risk factors.
07
Can you take too much vitamin D?
Yes. More is not always better.
Taking excessive amounts of vitamin D from supplements can be harmful and can cause too much calcium to build up in the body.
Do not exceed recommended supplement amounts unless a doctor or other qualified healthcare professional has advised you to do so.
People with medical conditions, people taking medicines, pregnant or breastfeeding people, and anyone being treated for vitamin D deficiency should seek appropriate professional advice about supplementation.
08
Thinking about a vitamin D supplement?
We are currently developing our vitamin and supplement resources.
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