As featured in a Cancer Research UK article, most people know, getting enough sun is excellent for you, but getting too much isn’t. UV rays in sunlight are the main culprit of skin cancer, but sunshine is needed in producing essential vitamin D.
One of the dangers of having low vitamin D is rickets, and in recent years it has increased slightly. This suggests that some people are not spending enough time outside in the sun. Interestingly, skin cancer rates are rising, for example, almost 16,000 people are diagnosed with melanoma every year in the UK.
Depending on your skin type, the amount of sunlight exposure you need to get enough vitamin D varies. However, the balance of how long people need to spend in the sun to generate enough vitamin D while minimizing their skin cancer risk remains unclear.
That’s where research from Professor Lesley Rhodes, at the University of Manchester, comes in.
In a study, Rhodes and her team looked at the impact of exposing 39 people of different skin types to low levels of UV. The questions Rhodes was hoping to answer were; would that be enough to generate vitamin D? And will this cause DNA damage in their cells that could lead to skin cancer?
Differing from previous studies, Rhodes gave participants UV doses related to their burning risk.
When the dose of UV exposure increased closer to their individual burning level, there was an increase in both vitamin D levels and DNA damage seen in skin samples. The relationship between these two factors seemed to be true of all skin types tested.
Rhodes goes on to explain his motivation for understanding the differences in skin type – “Quite a lot of information has been gathered on white-skinned people, but there’s been very little for people with darker skin. We needed to firm up our knowledge by looking at the major benefit and the major harm of sunlight at the same time in each person.”
Funnily enough, the findings differed fro skin types when researchers looked at the lower layer of the skin, where damage is most dangerous. For darker skin types DNA damage wasn’t detected at this lower level, it was mostly at the surface. In lighter skin types DNA damage was found throughout the layers, meaning there was more potentially dangerous damage lower down. “This was a really novel discovery, that the darker the skin color the closer the DNA damage was to the surface,” says Rhodes.
Regardless of dose or skin type, the DNA damage was no longer present 48 hours later. Our bodies can deal with some level of DNA damage and the level of damage in the study seemed to be low enough to be cleared shortly after. Although this is reassuring, the study can’t rule out the possibility that damage like this could go on to cause problems. And Rhodes is keen to study this more in the future.
From the findings, it appears that DNA damage is happening before skin burns. Also, people with lighter skin types are more likely to experience damage than darker ones. However, more extensive studies will be needed to verify those results.
“People with darker skin can be encouraged to expose their skin to the sun, without burning, to get vitamin D with very low risk of skin cancer,” says Rhodes. “However, for people with lighter skin who are easy burners we’ve shown even very low doses of UV radiation, down to one-fifth of their sunburn threshold, can, unfortunately, damage the cells in lower layers of the skin.”
“We wanted to define a fairly straight-forward formula for how much sunlight people would need in the UK to get enough vitamin D,” says Rhodes. “People are always asking ‘how much?’, but it’s not quite as simple as just talking about minutes, you also need to look at what area of skin you need to expose and at what time of day.”
To do this, she teamed up with Professor Ann Webb, a physicist with expertise in the atmosphere and sunlight. They modeled the level needed by the end of summer for most people to have enough vitamin D throughout winter when the sun isn’t strong enough for us to make vitamin D in the UK.
They estimated that 9 minutes of lunchtime sunlight each day would be enough for Caucasians to stay above the ‘deficient’ category of vitamin D level throughout the year. This figure assumes that people would be in shorts and t-shirts for June to August, while only having their hands and faces exposed from March to June and for September.
Our bodies start to break down vitamin D when we’re generating a lot of it so you can’t do a week all in one go. Little and often does seem to be the key. You may only need to find a few minutes outside at lunchtime each day. But, like almost everything else in our daily lives, it won’t be completely risk-free, but it should give a healthy balance.
“People often think it’s a balance between getting enough vitamin D and avoiding skin cancer,” says Rhodes. “But our feeling is that quite often people may be justifying too much time in the sun in order to get their vitamin D. So it’s important to give people the information.
Please note, the contents of this article do not necessarily represent the official position of the PSMO. If you have any health concerns, please consult your general physician. For any cancer-related concerns and to ensure the best possible advice, please speak to a Cancer Expert. If you would like to reach out to the PSMO, please contact us here or search for your closest PSMO doctor here.