SPF facts and fiction

When it comes to advice about sun damage, you may have heard how it’s important to incorporate SPF into your daily skin care routine for 365 days a year; including winter. But here in the UK, a land of seemingly relentless grey skies where sunshine seems non-existent, have you ever wondered whether if it's worth the bother? Or, if using SPF could actually stop us getting any benefit from the small amount of rays we do get?

Here to dispel myths surrounding SPF, provide expert advice regarding vitamin D, and highlight the difference between UVA and UVB rays, is leading consultant dermatologist Dr Karishma Hemmady.

In the UK, a northern island where the sun barely shines in the winter, are the rays really strong enough to cause ageing?

Even in areas with limited sunlight during the winter months, the sun’s ultraviolet (UV) rays can still cause skin damage. While UVB rays, which cause sunburn, are less intense in the winter, UVA rays are present year-round and can penetrate clouds and glass. UVA rays are responsible for the deeper skin damage that leads to ageing, such as wrinkles and loss of elasticity. Thus, even when it feels gloomy, the UVA rays are still active and can contribute to skin ageing.

Do we need to wear SPF every day?

Yes, wearing SPF every day is suggested, even in winter. However, this shouldn’t be at the expense of having a vitamin D depletion. Our body needs a small amount of UVB exposure to be able to synthesize vitamin D.

The UVA rays, which are the main contributors to premature skin ageing and skin cancer, are present all year round. Daily SPF application, particularly on exposed skin like the face, can protect against cumulative damage over time. It’s especially important if you're spending time outdoors, even on cloudy or overcast days. Hence, it’s important to not only use a sunscreen during winter, but also keep a track of vitamin D levels and take a vitamin D supplement if the levels are low.

What is the difference between UVA and UVB rays, and what is broad spectrum SPF?

UVA and UVB rays are significantly different:

UVA rays: These rays have a longer wavelength and penetrate deeper into the skin. They contribute to skin ageing (wrinkles, age spots) and can also damage DNA, leading to an increased risk of skin cancer.
UVB rays: These rays have a shorter wavelength and primarily affect the surface of the skin, causing sunburn. They’re responsible for vitamin D production but also play a significant role in the development of skin cancer.

Broad spectrum SPF provides the following:

Broad spectrum: This term means that a sunscreen protects against both UVA and UVB rays. A broad-spectrum sunscreen provides more comprehensive protection, as it shields against the damaging effects of both types of rays.

What SPF should we be wearing to actually protect us from harmful rays, and have anti-ageing properties?

For adequate protection, a broad-spectrum sunscreen with an SPF of at least 30 is recommended for everyday use. SPF 30 blocks about 97 per cent of UVB rays. If you're outdoors for extended periods or in direct sunlight, you may want to use SPF 50, which blocks about 98 per cent of UVB rays.

For anti-ageing purposes, it’s essential to apply sunscreen daily as UVA rays, which cause premature ageing, can even penetrate through windows.

Could wearing SPF stop us from getting important vitamin D?

While SPF does block UVB rays, which are responsible for vitamin D synthesis in the skin, most people still get enough vitamin D through incidental exposure or diet. For those who are concerned about their vitamin D levels, they can consider dietary sources (like fortified foods and fatty fish) or vitamin D supplements.

Short, unprotected sun exposure for 10 to 30 minutes a few times a week can also support vitamin D production without significantly increasing the risk of sun damage.

Is there any truth in the suggestion that SPF could stop us getting the full benefits of sunshine, and that too much SPF could cause seasonal affective disorder (SAD)?

SPF itself doesn’t block the overall ‘benefits’ of sunshine, but it does protect your skin from the harmful effects of UV radiation.

The concern about too much SPF leading to seasonal affective disorder (SAD) is, in my opinion, more psychological than physiological. While sunlight can help regulate mood by boosting serotonin levels and supporting circadian rhythms, the amount of sunlight required to feel the mood benefits doesn’t necessarily correlate with the amount of UV exposure required to damage your skin.

It’s important to balance sun exposure for both mood and skin protection. Brief exposure to sunlight (without sunscreen) is still helpful for vitamin D and mood without putting the skin at excessive risk.

References:

American Academy of Dermatology (AAD) – "Sunscreen FAQs" AAD
Skin Cancer Foundation – "How Sunscreen Protects Your Skin" Skin Cancer Foundation
British Association of Dermatologists – "Sunscreen & Sun Protection" British Association of Dermatologists

Are you worried about the effects of SPF on your skin? Dr Hemmaddy provides gold-standard treatment for skin cancer treatment, as well as other dermatological conditions. Arrange a consultation with her via her Top Doctors profile.