Why SPF Factor Alone Isn't Enough to Choose the Right Sunscreen?

By now it is common knowledge that sun exposure is causing skin damage, skin ageing, inflammation and in worst cases skin cancer. What we know is that the higher the SPF, the higher our protection level. Protection against UV is paramount but checking only the SPF on the bottle is not enough anymore. Read our blog below to discover the intricacies of modern day sunscreen.

What is UV-light?

As part of the non-visible light spectrum, UV light is being differentiated based on it's wave length: the shorter the wave length the higher the energy and the damage to us as living organisms. Luckily, the ozone layer of our athmosphere keeps away UVC-light, however, UVB and A are penetrating reaching the earth's surface.

The middle range UV-B light ranges from 280-315nm and only 85% is being absorbed in the ozone layer. It only penetrates the superficial epidermis skin layer but it causes sun burn and skin cancer.

The UV-A light is longer, ranges from 315-400nm and will completely penetrate the ozone layer making it imperative to protect against. It reaches deeper skin layers and is responsible for increased oxidative stress, dangerous DNA damage and photo-aging.

What does SPF exactly mean?

The SPF - Sun Protection Factor of a product expresses the time it takes untanned skin to redden with sun screen applied at a specific dosage of 2mg/sqcm in comparison/relation to unprotected, untanned skin. Becuse of this specific parameter used, the skin redness/erythema, it is a measure of the superficially penetrating UVB light, which causes sun burn. It is not measuring the effect of the deeper penetrating UVA light and it is not a measure of any other effects UV light might have on our skin, which for example may require less time to occur than it takes skin redness to happen. In the laboratory we can also test the % of UVB light filtering capability.

As an example and a quite surprising one I would say: SPF 30 will filter 96% of the UVB light while the SPF 50 will achieve 98% UV-light filtration. So far so good, just go for the high SPF numbers and you achieve maximum possible skin protection, right?

What else is missing?

Interestingly, despite the appropriately rising sun screen usage, skin cancer has not decreased in recent years. Skin melanoma is the number one cancer in children and young adults, which made researchers think that there is something missing from the simple picture. And it is quite obvious: as I already mentioned, SPF factor is only measuring the effect UVB light has on skin erythema or redness but what about the other detrimental effects of UV-light on our skin? Just because we prevent skin redness, does it mean that we also prevent all the other damaging effects in the deeper skin layers, especially DNA damage and oxidative stress, the biggest factors causing skin cancer and photo-aging?

The answer is simple: NO!

What is UV-induced skin damage exactly?

Decades of research has shown several molecular pathways how UV light, A and B, causes damage to the skin and these are not taken into account when measuring the SPF.

- DNA & RNA-damage, sevral pathways have been described, all leading to an increased risk of photo-induced carcinomatosis (skin cancer)

- Oxidative stress and ROS overproduction (Reactive Oxygen Species, free radicals) will cause altered extra-and intracellular function on different levels: faulty enzymatic activity, further DNA damage, remodeling of the extracellular matrix, faulty mitochondrial function and cellular energy metabolism, leading to several detrimental effects on our skin, including acute and chronic inflammation.

- Skin photo-aging: due to acute inflammatory processes caused by UV-light we see a process of complete restructuring in the deeper skin layers, similar to scarring after acute wound healing, which goes hand in hand with ECM (extracellular matrix) remodeling, dysrupture of collagen cross-linking and and elastin degradation.

- UV-induced immunosuppression: a direct effect of UV-light on a multitude of immuno cells, causing dysruption of healthy behavior, concerning lymphocytes, macrophages and other blood cells. Immunosuppression does not only lead to diminished pathogen clearance from our system but also plays a critical role in cancer formation. We call this process „photocarcinogenesis“.

Outlook beyond the SPF factor: biological anti-skin damage modulators are the future!

Taking all the above into account, we understand that the optimal sun screen would look beyond the mandatory UV-light filters and the achievement of a high SPF. Adding strong antioxidants like Vitamins and Astaxanthin and many other potent natural modulators like Carotenes and Polyphenols, Capsanthins and to the formula, is what makes the ultimate difference, when it comes to deep skin protection against detrimental UV-light. Despite this knowledge, most commercial sun screen will rarely provide additional ingredients, a study showed that only a few products on the market will have more than one antioxidant on board, the most common one being Tocopherol, the most commonly used Vitamin in cosmetics.

Nevertheless, nature offers a wide variety of protective substances! Throughout natural evolution, each living organism, plant or animal, had to develop their own UV-light protection mechanisms. Searching for the right extraordinary ingredients, understanding what their role may be in the complex cascades of detrimental skin damaging effects of UV-light, and creating the right mix potentiating their individual effect and attacking the „problems“ from many different angles, is the big challenge when it comes to modern sun screen formulation.

Li Lé blue has taken a first step. Our facial sun screen has chosen the strongest antioxidant ingredient, Astaxanthin, as a deep skin protector in addition to the standard UV-filter ZincOxide. Astaxanthin is not only known for its anti-oxidative super power, 6000 times stronger than Vit C, but also for specific immun-modulating properties, reducing pro-inflammatory interleukins, inhibiting pro-cancerogenic pathways and counteracting photo-aging effects by protecting the extracellular matrix, maintaining collagen and elastin. The UV-protective effect of Astaxanthin is unparalleled and well researched, as supported by several scientific studies.

Take home message:

SPF alone is not enough when you chose the right sunscreen. Specific antioxidants and many other positively modulating natural substances are key to improve the efficacy of the sunscreen you need, protecting your skin thoroughly beyond the measurable SPF!

Copyright Dr. Manuela Reisbeck for Li Lé blue

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