Fair-skinned people who burn easily in the sun may need to take vitamin D supplements, according to research.
Vitamin D is essential for healthy bones and people get most of what they need from exposure to sunlight during the summer months.
While there is not one recommendation to suit everybody, short daily periods (10 to 15 minutes) of sun exposure without sunscreen during the summer months are enough for most.
But a new study funded by Cancer Research UK has found that people with very pale skin may not be able to spend long enough in the sun while also avoiding sunburn.
It suggests that the increased risk of skin cancer from excessive sun exposure outweighs any vitamin D benefit for fair-skinned people.
Professor Julia Newton-Bishop, author of the study, said: "Fair-skinned individuals who burn easily are not able to make enough vitamin D from sunlight and so may need to take vitamin D supplements."
Sara Hiom at Cancer Research UK said: "We must be careful about raising the definition of deficiency or sufficiency to higher levels until we have more results from trials showing that maintaining such levels has clear health benefits and no health risks."