Cancer Research UK has launched a trial investigating the health benefits and risks of spending time in the sun.

It is hoped the trial will help solve years of controversy surrounding vitamin D, the ‘sunshine vitamin’, and how much sun is too much.

The amount of sun exposure needed to make enough vitamin D varies from person to person, largely dependent on skin colour.

But at the moment there are no clear guidelines about what level of sun exposure is needed to produce enough vitamin D without causing excessive DNA damage to the skin, which can cause skin cancer.

This Cancer Research UK-funded trial will use simulated sunlight to determine whether certain amounts of sun are beneficial for certain skin types, and how much is too much.

Study leader Professor Lesley Rhodes, from the University of Manchester, said: “There’s no doubt that too much sun can seriously increase skin cancer risk, but we know there are also important benefits to going out in the sun, such as making enough vitamin D. This study is about finding that balance, so we can offer people of all skin colours the best possible advice about how much sun is safe for them.”

Seventy-five healthy volunteers aged 18-45, and with a range of skin colours, are being recruited to take part in the study in the Photobiology Unit, Dermatology Centre at Salford Royal in Greater Manchester.

Wearing standardised clothing, participants will be exposed to simulated sunlight - equivalent to that of a summer’s day in Manchester - for short periods of time.

Blood and urine samples will be taken after exposure and examined for chemicals that indicate vitamin D levels and DNA damage. Small skin samples will also be taken from some volunteers and analysed for any signs of DNA damage.

Kalani Hargrove, who is studying a Masters in sociology at the University of Manchester and is one of the first volunteers to take part in the study, said: “Before I signed up for the study I was given an information sheet that explained everything. Taking part has been really simple and straightforward so far and it’s been fascinating to see firsthand how medical research is carried out. I’m delighted to be taking part in research that will hopefully lead to a better understanding of how people of all skin colours can enjoy the sun safely.”

Sara Hiom, director of information at Cancer Research UK, said: “Sun is a really important source of vitamin D, but the amount of sun needed varies from person to person. We know that people with paler skin make vitamin D faster, but burn more easily, than those with darker skin, but it’s still not completely clear where the balance lies in terms of getting enough vitamin D, without excessively increasing skin cancer risk.

“Studies like this, which use simulated sunlight so we can compare the results for people with different skin types, will tell us much more precisely how much sun is safe for different people. In the meantime, continue enjoying the sun, but remember that the amount of time you need to spend in it to make enough vitamin D is always less than would make your skin redden. The best way to protect your skin from sunburn is to use shade, clothing and at least factor 15 sunscreen applied generously and regularly.”

Source: CRUK