Sunshine, SPF and the Science Inbetween
Sometimes you can’t beat the Sunday dinner table when it comes to lively family debates. Last Sunday we found ourselves discussing the safety of sun exposure and the use of SPF. I’d seen bits and pieces about this online, so I decided to do a bit more digging to find the facts and ultimately determine who was right.
The health benefits of sunlight
According to the Cleveland Clinic, sunshine boosts vitamin D, which our bodies need in order to absorb calcium and keep our bones healthy. Around 90% of our vitamin D comes from sunlight.
Access to sunlight also boosts your mood, through natural increases in serotonin, improves energy levels and aids sleep. They go on to say that 10 to 30 minutes of sunlight, on bare skin, can be enough to provide these benefits.
Another significant benefactor from sunlight is cardiac health. Sunlight triggers the release of nitric oxide into the bloodstream, dilating the blood vessels which, in turn, lowers blood pressure and reduces the risk of heart attacks and strokes.
In Scotland the amount of sun we’re exposed to is low, compared to most other countries, and that’s not necessarily a good thing. In fact, a study by The University of Edinburgh in 2024 suggested that for those living in areas with limited sunshine, spending more time in the sun could be beneficial:
‘Our paper adds to a growing body of evidence suggesting that in lower light environments, relatively higher exposure to UV is good for your health. Though there may be an increased risk of skin cancer incidence with higher UV exposure, this risk appears to be outweighed by a larger reduction in the risk of death from cancer and cardiovascular related disease.’
Professor Chris Dibben, University of Edinburgh’s School of GeoSciences
Further research, by Professor Richard Weller from University of Edinburgh’s Centre for Inflammation Research, also highlights that for every death from skin cancer caused by excess sunlight there are 75 deaths from other causes that may be prevented from sufficient sunlight exposure, including cardiovascular disease and cancer.
This is supported by studies that show the UK population’s blood pressure is higher in winter than in summer, resulting in a 23% rise in cardiovascular-related deaths.
If you are a male in living in Scotland, you are 30% more likely to die in January than in July.
So it’s a good thing we have some good skiing, scenic snowy mountains and award winning golf courses to encourage us outdoors in the winter.
The harmful side of UV
All that being said, before you go running for the deck chairs, just like everything else there is such a thing as too much.
Your skin is your largest and arguably your most vital organ. It acts as your body’s protective barrier to the outside world, and sun damage weakens these natural defences. Over time, excessive UV exposure can impair the skin’s ability to protect against pathogens, toxins and other environmental factors.
Skin cancer is of course the most talked about risk. In the UK melanoma is the 5th most common cancer with over 16,000 new cases diagnosed annually and over 2,000 deaths each year. Numbers have increased by over 30% in the last decade, with over 80% of cases thought to be preventable.
According to Cancer Research UK a significant proportion of melanoma cases are linked to intermittent, high-intensity sun exposure, such as sunbathing on holidays abroad. People who get intense, short bursts of sun are at much higher risk than those with regular, low-level sun exposure.
And if health risks aren’t enough, there are aesthetic consequences too. Sun damage accelerates ageing, leading to premature wrinkles, pigmentation and the familiar ‘leather look’. By the time these signs appear, the underlying DNA damage has already been done.
So how much is too much?
Well, that depends on a number of factors.
- Your location
- The time of day
- Your skin tone
- Your own, individual susceptibilities
Obviously there’s a big difference between lazing in the Californian midday sun and sitting with your coffee in the garden on a sunny morning in the UK. Current guidance generally recommends protection when the UV index reaches 3 or above.
Melanin, the natural pigment in our skin, acts as a form of built-in sunscreen. Fairer skin contains less melanin, which means darker skin does offer more natural protection against sun damage. As well, people with darker skin types also typically require more sun exposure to produce sufficient vitamin D, particularly in northern climates.
For anyone who’s interested, there is a scale called ‘The Fitzpatrick’ which classes skin types based on their sensitivity to UV light and therefore how much protection is required.
Sun Protection Factors - SPFs
In the last few years there has been some controversy around SPFs being a health risk in themselves. This centred largely around the chemicals used in these products, such as oxybenzone, a known endocrine disrupter which interferes with the regulation of hormones and metabolism. Brands have tended to move away from this chemical as a result.
The other chemical concern is nanoparticles, namely those of zinc-oxide and titanium dioxide. Nanoparticles make it easier for your skin to absorb the creams and provide better coverage but their size does mean they can enter your body at a cellular level and cause damage.
When it comes down to the cancer risk, the scientific consensus is clear: excessive UV exposure outweighs the known risks of approved sunscreen ingredients.
(As well, there are concerns that these particles are damaging to the environment with an estimated 14,000 tonnes of sunscreen ending up in the sea every year disrupting marine life. We know that nanoparticles are absorbed by coral, for example, contributing to bleaching and causing extensive damage to coral reefs)
The Product Matters
As well as the ingredients in the SPF, investigations into a number of popular sunscreens found that some products provide significantly less protection than advertised. Testing by Which? identified several sunscreens labelled as SPF 30 or SPF 50 that failed to meet their claimed level of protection.
So research your sunscreen choices and buy reputable brands that provide protection suited to your skin type and the level of sun exposure you expect each day.
Enjoy the sunshine.
The real takeaway from our Sunday dinner debate is that the sun isn’t something to fear but it’s also not something to ignore. I guess at some level we were all right!
Common sense and sunscreen, as required.
Sources:
University of Edinburgh. (2024). UV rays may boost health in low-sunlight countries.
https://www.ed.ac.uk/news/2024/uv-rays-may-boost-health-in-low-sunlight-countries
University of Edinburgh, Institute for Regeneration and Repair. (2024). Sun awareness: Should we rip up the rule book and start again?
Naïf Care. (2024). Nano versus non-nano sun care.
https://naifcare.com/en-nl/blogs/nano-versus-non-nano-sun-care
Cancer Research UK. (n.d.). Risks and causes of melanoma.
https://www.cancerresearchuk.org/about-cancer/melanoma/risks-causes
NHS Scotland. (n.d.). Sun awareness story.
https://healthandcare.scot/mobile_default.asp?page=story&story=4319