Microbiome Under the Sun: Rethinking UV Protection

Shalindri Jayawardene
May 7
3 min read

The skin microbiome is vital for skin health and barrier integrity. Sun exposure, especially UV radiation, plays a significant role in modulating this ecosystem. While moderate sun exposure aids vitamin D synthesis, excessive UV radiation disrupts microbial balance, causing oxidative stress and altering microbial composition. Understanding the interaction between UV and the skin microbiome is crucial for advancing skincare and overall skin health.

What we know:

A significant shift in microbial beta diversity was observed on the forearms of participants after four weeks of extensive sun exposure compared to baseline, suggesting that sunlight alters the diversity and composition of the skin microbiota (Willmott et al., 2023).

An overall increase in Cyanobacteria, Fusobacteria, Verrucomicrobia, and Oxalobacteraceae species was observed, while Lactobacillaceae and Pseudomonadaceae species showed a decline after UVR exposure (Gilaberte et al., 2025).

Research shows that bacteria, like skin cells, react differently to UVA and UVB light. One study found both UV types reduce Pseudomonas aeruginosa, but Escherichia coli was less affected by UVA, indicating varying bacterial responses to sunlight (Smith et al., 2023).

A study found that SPF 20 sunscreen protects both skin and its microbiome, preventing erythema and preserving beneficial bacteria like Lactobacillus crispatus. In contrast, unprotected or placebo-treated skin showed a disrupted microbial balance, with a reduced Lactobacillus to Cutibacterium acnes ratio (Schuetz et al., 2024).

Applying sunscreen prior to UV exposure helps support and protect the skin microbiome, and researchers suggest that using sunscreens with higher SPF levels could provide even stronger microbial and skin protection (Schuetz et al., 2024).

Industry impact and potential:

The growing awareness of how sun exposure affects the skin microbiome is driving innovation in sun care. Research indicates that UV protection can influence the balance of skin microorganisms, paving the way for products that not only shield against sun damage but also support overall skin health.

Further research is needed to understand how different UV wavelengths impact the skin microbiome and contribute to long-term skin health issues, including aging and chronic conditions. More studies are also required to evaluate how various sunscreen formulations affect the skin’s microbial balance (Gilaberte et al., 2025).

Our solution:

At Sequential, we help skincare brands create sun care products that protect the microbiome and support skin health. Through in vivo testing and detailed analysis of formulations' impact on the skin’s microbial ecosystem, we ensure products deliver UV protection without disrupting microbial balance. With access to over 20,000 microbiome samples, we provide scientifically-backed solutions that meet the growing demand for skin care prioritizing long-term health and immediate benefits.

References:

Gilaberte Y, Piquero-Casals J, Schalka S, Leone G, Brown A, Trullàs C, Jourdan E, Lim HW,

Krutmann J, Passeron T. Exploring the impact of solar radiation on skin microbiome to develop improved photoprotection strategies. Photochem Photobiol. 2025 Jan-Feb;101(1):38-52. doi: 10.1111/php.13962. Epub 2024 May 20. PMID: 38767119; PMCID: PMC11737011.

Schuetz R, Claypool J, Sfriso R, Vollhardt JH. Sunscreens can preserve human skin

microbiome upon erythemal UV exposure. Int J Cosmet Sci. 2024 Feb;46(1):71-84. doi: 10.1111/ics.12910. Epub 2023 Oct 6. PMID: 37664974.

Smith, M. L., O’Neill, C. A., Dickinson, M. R., Chavan, B., & McBain, A. J. (2023). Exploring

associations between skin, the dermal microbiome, and ultraviolet radiation: advancing possibilities for next-generation sunscreens. Frontiers in Microbiomes, 2, Article 1102315. https://doi.org/10.3389/frmbi.2023.1102315

Willmott T, Campbell PM, Griffiths CEM, O'Connor C, Bell M, Watson REB, McBain AJ,

Langton AK. Behaviour and sun exposure in holidaymakers alters skin microbiota composition and diversity. Front Aging. 2023 Aug 8;4:1217635. doi: 10.3389/fragi.2023.1217635. PMID: 37614517; PMCID: PMC10442491.