The summer holidays are over, term has restarted for a couple of my kids, one is off to university shortly and we’re back at work. A huge part of a dermatologist’s work, in the south east of England at least, is in skin cancer management. The majority of skin cancers we see are directly linked to sun exposure. This could be in childhood, a life spent living and working in the Tropics, second homes abroad, spending time outside gardening, looking after horses or playing sport or having two weeks of blistering sunburn on an annual sunny holiday. So we do have to give out a lot of sun avoidance and sun protection advice as part of our job.
It’s extremely interesting therefore to hear that in Australia, a position statement was published in July 2023 outlining how to balance the harms and benefit of sun exposure. On the back of this, research at the University of Edinburgh which was published this month showed that higher UV exposure is associated with lower mortality from cardiovascular disease and cancer.
[Neale RE, Whiteman DC, Beedle V et al. Position statement: balancing the harms and benefits of sun exposure. The University of Queensland. https://doi.org/10.14264/17c76bd]
[Stevenson AC, Clemens T, Pairo-Castineira E et al. Higher ultraviolet light exposure is associated with lower mortality : An analysis of data from the UK biobank cohort study. Health & Place 2024;89:103328]
What did the position statement in Australia say?
It was basically about vitamin D and its benefits on various health outcomes such as bone strength but also its effects on the immune system. Young people in Australia are starting to show declining rates of skin cancer but many are now becoming vitamin D deficient, especially in the winter months.
Can’t you just get your vitamin D from your diet and supplements?
Yes, that is true. But the position statement goes on to state that there are additional benefits to sun exposure which occur independently of vitamin D. For example, spending time outdoors encourages more physical activity. Exposing the eyes to the UV rays in sunlight influences our circadian rhythms, improves sleep and mood and reduces the risk of myopia (or short-sightedness). Completely avoiding the sun is not healthy.
So what are their recommendations?
The recommendations are for adults and are divided into three groups (those at high risk, low risk and intermediate risk of skin cancer).
Those at high risk should always employ sun protective measures when outdoors if the UV index is greater than or equal to 3. Vit D supplements should be taken and going outside when the UV index <3 is recommended.
For those at low risk of skin cancer ie dark skinned people, they advise sun exposure when the UV index is greater than or equal to 3 and sun protection only if spending extended time outside.
For those at intermediate risk of skin cancer ie olive or pale brown skin, they recommend spending sufficient time outdoors with skin exposed to the sun to obtain a “vitamin D-effective dose”. Any more than that and sun protective measures should be employed.
What is a “vitamin D effective dose” of sun?
This is the tricky bit. It depends on skin type, how much skin is exposed, how long you are outside, geographical location, time of day, the season, cloud cover.
They do however, highlight that the amount of sun to get a vitamin D effective dose will not cause the skin to go pink or red. For most people, it will be obtained by incidental sun exposure. In the Australian summer, only a short time outside will do it, and of course, in the Australian winter, more time will be needed.
That is all fair and well but we are not Australia!
That is also true. The UK is a high latitude and low sunlight country. The UV index rarely gets above 6 and most of the population are vitamin D deficient especially during autumn and winter. The NHS recommends that children between the ages of 1 and 4 should take 10 micrograms of vitamin D all through the year.
What did the UK study look at?
The researchers at the University of Edinburgh looked at data from the UK Biobank, a repository of data on 500,000 participants. They looked at sunbed use, residential shortwave radiation (SWR, a measure of incoming solar energy over the Earth’s surface), vitamin D levels, mortality rates, death due to cardiovascular disease, cancer, melanoma incidence and mortality and non-skin cancer incidence and mortality.
What did they find?
They found that sunbed users and those with higher residential SWR had higher levels of vitamin D.
After adjusting for confounders eg age, gender, smoking, socio-economic status, exercise, they found that sunbed users had a 15% lower risk of all-cause mortality, a 23% lower risk of death from cardiovascular disease, a 14% lower risk of death from cancer and a 12% lower risk of death not due to cardiac disease or cancer compared to non-sunbed users.
Those whose annual average residential SWR was 2000 J/m2 higher ie lived somewhere more sunny, also had a 12% lower risk of death from any cause, a 19% lower risk of death from cardiovascular disease and a 12% lower risk of death from cancer.
Most interesting of all to me, though sunbed users/those living in higher residential SWR areas had a higher incidence of melanomas, it was not associated with an increased death rate from melanoma.
So where do we go from here?
The researchers in Edinburgh do point out that there are lots of confounding issues in their study. Most of the participants were of white European ancestry, many were healthy volunteers, residential SWR does not take into account what a person does away from their home, there can be recall bias in recalling sunbed usage and suncream use was not included.
The study was also performed in a country with low sunlight levels. The authors are quick to point out that the story may well be different for people with different skin colours in different parts of the world.
Definitely, more work needs to be done in this area so that more nuanced sun protection advice can be given for different groups of people.
Kind regards,
Sandy
Dr Sandy Flann, Consultant Dermatologist.
