Exposure to sun without sunscreen boosts vitamin D, study claims

The study, conducted at The University of Manchester and led by ultra-violet radiation expert Ann Webb, supports claims that exposing unprotected skin to the sun for short periods helps the body to produce essential Vitamin D.

The findings will not be accepted whole heartedly by world-wide cancer associations, many of whom are worried about the repercussions the mixed message the study might appear to send out.

The American Cancer Society​ estimates that most of the more than 1 million cases of nonmelanoma skin cancer diagnosed yearly in the nation are considered to be sun-related. Melanoma, the most serious type of skin cancer, will account for about 59,600 cases of skin cancer in 2005 and most (about 7,800) of the 10,600 deaths due to skin cancer each year.

However, Dr Webb's study emphasizes the beneficial effects of sun for Vitamin D production, while also limiting that unprotected sun exposure should be limited.

Dr. Webb's says that new figures can not only predict when is the best time to expose unprotected skin to the sun in order to maximise Vitamin D production, but also for how long - depending on location. She has calculated that 'ten to fifteen minutes at noon' is the optimum time for the average person in the UK to spend in the sun without the use of sunscreen.

This figure obviously varies greatly, depending on the time of the year and the proximity to the equator, which as a general rule means that the nearer to this point the stronger the sun might be.

"Our calculations have found that the best time to be out in the sun if you want to maximise Vitamin D production and its benefits is midday. This is when the sun is highest in the sky and this is when there is more UVB radiation in the spectrum which triggers Vitamin D production in the skin,"​ says Dr Webb.

Vitamin D promotes the absorption of calcium and phosphate from food and is essential in the formation of bones and teeth. A deficiency of Vitamin D leads to a failure of the bones to grow and causes rickets in children and osteoporosis in adults. Recent research also suggests that Vitamin D can help reduce the risks of colon, breast and prostate cancer.

Dr Webb added: "The two sources of Vitamin D are through your skin or through foods like sardines (fatty fish), but because our everyday diet isn't very rich in the vitamin it is essential that we get it from the sun,"​

Falling in line with warnings on over-exposure to the sun, Dr. Webb also emphasised that her advice should be taken responsibily and that sunscreen is essential as part of this.

"You do not need to sunbathe to get your Vitamin D and we are not advocating people do not protect themselves with sunscreen, but if you put sunscreen on before you step out of the house you will not reap any health benefits provided naturally by the sun. After a short period of unprotected exposure you should cover up or put on sunscreen to avoid sunburn."​

The research, which has been carried out in conjunction with experts at the Norwegian Institute for Air Research, uses computer simulations based on global UV data to calculate optimum times for Vitamin D production based on season, time and latitude. The programme can be run for any time of day and can calculate optimum exposure times for any location in the UK or abroad.

Calculations for optimum Vitamin D sun exposure in spots all over Europe were made for individuals with fair skin wearing t-shirts and shorts or a skirt in the early summer. Dr. Webb's team came up with estimates ranging from 11 minutes for Edinburgh and 9 minutes for London in the UK, to 6.5 minutes for Athens, Greece and 7 minutes for Marseilles in the South of France.

Cancer Research UK​ launched a Sun Smart campaign this year that emphasizes individuals should use SPF 15 + sunscreen and cover up as much as possible during the hours of 11am and 3pm to avoid any type of burning.