DAILY RITUAL: SUNSCREEN

The American Academy of Dermatologists recommends the use of broad-spectrum, SPF 30 sunscreen every day to lower the risk of skin cancer [1]. But what does the data say? Does it work? How does it work? And will any sunscreen do the trick? In this article, we will explore the considerations of choosing the right sunscreen and choosing to wear it every day. We’ll also shed light on its effects on aging, melanin, oxidative damage, and dive deeper into the molecular biology of sun damage to the skin.

BENEFITS OF DAILY SUNSCREEN USE

Reducing Oxidative Damage: 

UV radiation from the sun generates free radicals that can lead to oxidation of cellular membrane lipids and proteins which reduce the skin’s overall motility and rate of skin cell turnover [2]. Oxidative damage to DNA is also a mechanism by which UV radiation exposure increases our risk for skin cancer. Sunscreens containing antioxidants can provide an added advantage in neutralizing these harmful free radicals, reducing oxidative damage. By mitigating this process,sunscreen plays a vital role in preventing DNA damage, inflammation, and other negative effects associated with free radicals. 

Protection Against Premature Aging: 

Sunscreen acts as a shield against UV radiation, which is one of the leading causes of premature aging. Exposure to UV rays can accelerate the breakdown of collagen and elastin, resulting in fine lines, wrinkles, and sagging skin [3]. By wearing sunscreen daily, you create a barrier that helps prevent these signs of aging, keeping your skin youthful and healthy.

Safeguarding Melanin: 

Melanin is the pigment responsible for skin color, and it offers some natural protection against UV radiation. However, even individuals with darker skin tones can still suffer from sun damage [4]. By wearing sunscreen regularly, people of all skin types can maintain the integrity of their melanin and prevent issues like hyperpigmentation and uneven skin tone caused by UV exposure. 

MOLECULAR MECHANISMS OF PHOTOAGING

When UV radiation reaches the skin, it penetrates the epidermis and dermis, causing oxidative damage to our cells [5]. UVB rays primarily affect the epidermis, leading to sunburns and increasing the risk of skin cancer. UVA rays, on the other hand, penetrate deeper into the dermis, causing oxidative stress, DNA damage, and long-term skin aging effects. Sunscreen's active ingredients work by either reflecting or absorbing UV radiation, preventing it from reaching and damaging the skin cells. They act as a physical or chemical barrier, reducing the harmful effects of both UVA and UVB rays.

LET’S GET PHYSICAL

Not all sunscreens are created equal. Chemical sunscreens rely on the active ingredients oxybenzone and avobenzone which have been shown to be absorbed systemically into the bloodstream at levels above the FDA recommended threshold [6]. Since the internal effects of these ingredients at this dose are not well understood, we recommend using mineral (physical) sunscreens with the active ingredients titanium dioxide and zinc oxide which instead reflect UV radiation. 

CONCLUSION

Wearing sunscreen every day offers significant benefits in terms of protecting the skin against premature aging, safeguarding melanin, and reducing oxidative damage caused by UV radiation. We recommend using a mineral-based, broad-spectrum sunscreen with an appropriate SPF each day [7]. New technologies have allowed for less pasty, non-comedogenic mineral sunscreens. Remember, while sunscreen is a valuable tool in sun protection, it should be complemented with other sun-safe practices, such as seeking shade during peak sun hours, wearing protective clothing, and using sunglasses. Taking a comprehensive approach to sun protection ensures a healthy and vibrant complexion while reducing the risks associated with excessive sun exposure.

Sources:

[1] Perez M, Abisaad JA, Rojas KD, Marchetti MA, Jaimes N (2022) Skin cancer: Primary, secondary, and tertiary prevention. Part I.J Am Acad Dermatol 87, 255–268.

[2] Salminen A, Kaarniranta K, Kauppinen A (2022) Photoaging: UV radiation-induced inflammation and immunosuppression accelerate the aging process in the skin.Inflamm Res 71, 817–831.

[3] Rittié L, Fisher GJ (2015) Natural and Sun-Induced Aging of Human Skin.Cold Spring Harb Perspect Med 5, a015370.

[4] Taylor SC, Alexis AF, Armstrong AW, Chiesa Fuxench ZC, Lim HW (2022) Misconceptions of photoprotection in skin of color.J Am Acad Dermatol 86, S9–S17.

[5] Shin J-W, Kwon S-H, Choi J-Y, Na J-I, Huh C-H, Choi H-R, Park K-C (2019) Molecular Mechanisms of Dermal Aging and Antiaging Approaches. Int J Mol Sci 20, 2126.

[6] Matta MK, Zusterzeel R, Pilli NR, Patel V, Volpe DA, Florian J, Oh L, Bashaw E, Zineh I, Sanabria C, Kemp S, Godfrey A, Adah S, Coelho S, Wang J, Furlong L-A, Ganley C, Michele T, Strauss DG (2019) Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial. JAMA 321, 2082–2091.

[7] Addor FAS, Barcaui CB, Gomes EE, Lupi O, Marçon CR, Miot HA (2022) Sunscreen lotions in the dermatological prescription: review of concepts and controversies.An Bras Dermatol 97, 204–222.