Which vitamin does your skin make from sunlight?
General information only. This article explains the basics and is not medical advice. For anything about your own health, talk to a doctor or other qualified professional.
Quick answer
Your skin makes vitamin D when it’s exposed to UVB rays in sunlight. Vitamin D helps the body absorb calcium and phosphate, which keep bones, teeth and muscles healthy. It’s sometimes called the “sunshine vitamin.”
Unlike most vitamins, vitamin D doesn’t have to come from food; the body can make its own when sunlight hits the skin.
How the skin makes vitamin D
- UVB light hits a cholesterol-based substance in the skin.
- It changes into an inactive form of vitamin D.
- The liver and then the kidneys convert it into the active form the body uses.
What affects how much you make
| Factor | Effect |
|---|---|
| Season and latitude | In places like the UK and northern US, winter sunlight is too weak for the skin to make much vitamin D |
| Time of day | Midday sun is strongest |
| Skin tone | Darker skin needs more sun to make the same amount |
| Age | Older skin makes less |
| Clothing and sunscreen | Block UVB rays |
| Glass | Sitting by a window doesn’t work; glass blocks UVB |
Food sources
Few foods naturally contain much vitamin D. Sources include:
- Oily fish such as salmon, sardines and mackerel
- Egg yolks
- Red meat and liver
- Fortified foods, such as some breakfast cereals, milks and spreads
Why it matters
Vitamin D helps keep bones strong. A severe lack of it can lead to bone problems such as rickets in children. Health agencies such as the NHS provide guidance on vitamin D for different groups and seasons; anyone unsure about their own needs should ask a doctor or pharmacist, since too much from supplements can also be harmful.
Balance sun safely
Your body doesn’t need sunburn to make vitamin D. Health services advise covering up or using sunscreen before skin starts to turn red or burn, to reduce the risk of skin damage and skin cancer.
For more on body chemistry, see which organ produces insulin. Sunlight also drives plant life; read what transpiration is.
Sources
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