A little sunlight every day is good for your health

No country conducts as much research into the effects of exposure to sunlight as Australia. If the guidelines for responsible exposure to sunlight change in that country, something is going on. The negative image of sunlight has had its day.

‘When it comes to sunlight, dermatologists have been fixated on skin cancer for years,’ says British professor and dermatologist Richard Weller in an article that appeared in the Daily Mail in April 2024. ‘As a result, dermatologists have forgotten that sunlight also has positive effects on health.’ The result of this one-sided view of sunlight was that educators and dermatologists advised everyone to protect their skin from the summer sun with clothing and to apply sunscreen to uncovered body parts such as hands and face.

Following this advice reduced the risk of skin burns – and indeed, skin that is burned multiple times is more prone to developing forms of skin cancer. But on the other hand, the experts' advice also means that people can hardly benefit from the positive health effects of sunlight anymore.

The UV-B light that burns the skin in excess also causes skin cells to produce vitamin D. While people who burn frequently do indeed have an increased risk of melanoma [a feared form of skin cancer], high vitamin D levels also improve the prospects for melanoma patients. According to a study published in the Journal of Clinical Oncology in 2009, optimal vitamin D levels not only increase the chances of recovery, but also reduce the likelihood of the disease returning.

‘The current advice [from the British health authorities] to limit direct exposure to sunlight as much as possible needs to be replaced,’ says Weller. ‘A lack of sunlight causes more deaths in the long term than sunlight itself.’ He refers to a Swedish study published in the Journal of Internal Medicine in 2014, which found that avoiding sunlight doubled the risk of death.

Australia as a guide

In Australia, the health authorities have now decided to change course. This turnaround will have consequences, because Australia is a leader when it comes to sunlight and skin. Because many people with white skin live in sun-drenched Australia, skin cancer is twice as common there as in Western Europe. According to some calculations, two out of every three Australians will develop skin cancer. For this reason, the country invests so much in research into sunlight that Australia has become a leading country in this field.

In the new guidelines, the Australians distinguish between three skin types: light skin that burns quickly but also produces vitamin D quickly, dark skin that does not burn quickly but produces vitamin D slowly, and light-coloured skin that falls between the two.

‘The main difference with the old guidelines is that we no longer tell people with dark skin that they must protect their skin from sunlight under all circumstances,’ says Anne Cust, a cancer epidemiologist and professor at the University of Sydney. Only if they are outside for several hours on sunny days should people with dark skin protect their skin from burning with clothing.

For people with fair or light-coloured skin, the updated Australian guidelines continue to take into account the risk of skin cancer. However, these two groups are now also advised to go outside and enjoy the sun in a sensible way.

A little UV light every day

The big problem with modern sun behaviour is that we avoid sunlight almost all year round, and then during a few weeks' holiday we expose ourselves to more sunlight than is good for our skin, explains British professor Weller. It is better to get a safe amount of sunlight outdoors every day between 11 a.m. and 3 p.m., which will not cause sunburn but will enable the skin to produce more vitamin D.

In Australia, the sunlight is so strong that people with fair skin who expose their face, arms and legs to daylight without protection will have absorbed enough UVB light within a few minutes. But in more northern areas, especially where the sun is regularly hidden behind clouds, this can take up to an hour. ‘This means that in a country like Great Britain, we need to focus on ways to capture more sunlight,’ says Weller. In England, as in the Netherlands, it is impossible for people with fair skin (who can therefore produce vitamin D relatively easily) to get enough sunlight in autumn, winter and the first months of spring to meet their vitamin D requirements. During this period, they therefore need supplements – or artificial UV light.

Supplements?

According to a 2016 American review study, a lack of sunlight increases the risk of premature death, colon cancer, breast cancer, prostate cancer, pancreatic cancer, high blood pressure, cardiovascular disease, type 1 and type 2 diabetes, obesity, Alzheimer's disease, multiple sclerosis, rheumatism, psoriasis and eye disorders. Vitamin D supplementation, intended to compensate for the lack of sunlight, can partially normalise the risk of these diseases and disorders – but not completely.

The positive health effects of sunlight go beyond vitamin D. For example, exposure to sunlight during the day ensures that the body's biological clock continues to function properly. This improves sleep quality and protects against cardiovascular disease. In addition, sunlight causes skin cells to release nitric oxide, which makes blood vessels more flexible and lowers blood pressure. ‘These processes have nothing to do with vitamin D,’ says Professor Weller. ‘Although taking a vitamin D supplement helps normalise the level of that vitamin, it does not provide all the other positive effects of sunlight.’