Vitamin D and skin: friendly or hostile light?

#VitaminD #SkinCancers #UVB #Photoprotection #PreventiveDermatology


Skin cancer is among the most common cancers worldwide. The most widespread forms are basal cell and squamous cell carcinomas, closely associated with chronic exposure to ultraviolet radiation. This link with UV rays, however, raises a paradox. Vitamin D3, synthesized by the skin under the effect of UVB rays, has anti-inflammatory, antioxidant, and antiproliferative properties, potentially protective against carcinogenesis. Yet its production depends on sun exposure, which is widely recognized for its harmful effects on DNA and its role in the development of skin cancers.

In this respect, current prevention strategies are essentially focused on strict photoprotection, raising the question of a functional vitamin D deficiency. This risk is particularly high among people with dark skin, the elderly, or populations living in regions with little sunlight. Moreover, topical or systemic treatments based on vitamin D are still poorly standardized, and their clinical effects remain uneven and insufficiently documented.  

This study was initiated to clarify the molecular mechanisms of cutaneous vitamin D3 synthesis and explore its derived metabolic pathways. Particular attention was also given to assessing the potential role of vitamin D3 in preventing skin cancers, while integrating data on new molecules from photometabolism.    

What if the sun also protected?  

This review is based on a critical analysis of the available scientific literature, including fundamental, experimental, and clinical work published over the past two decades. No original data collection was carried out, as the study is based exclusively on documentary sources. The research analyzed focuses mainly on the biological mechanisms of the synthesis, transformation, and activation of vitamin D3, as well as on its physiopathological implications.  
The analysis reveals that vitamin D3 and its derivatives exert antiproliferative effects on keratinocytes. Moreover, it promotes DNA repair, reduces UV-induced inflammation, and modulates the local immune response. It inhibits the progression of precancerous lesions into invasive tumors by acting on targets such as TP53, PTCH1, or p16.  

These studies also show that some alternative photoproducts of vitamin D have equivalent or complementary biological activity, without a hypercalcemic effect. These data therefore open the way to localized therapeutic applications, particularly in secondary prevention in at-risk individuals. The balance between sufficient exposure to induce endogenous synthesis, and selective photoprotection of sensitive areas, emerges as a strategic axis for personalized prevention.    

What if vitamin D became an ally against skin cancer?  

Skin cancers, especially non-melanoma forms, are closely linked to excessive sun exposure. Paradoxically, systematically suppressing this exposure could deprive the skin of a natural defense mechanism: the synthesis of vitamin D3. The challenge is therefore to find a balance between prevention and endogenous production, taking into account inter-individual variability (phototype, age, lifestyle habits).  

This review aimed to explore the role of vitamin D and its photoderivatives in skin cancer prevention, by clarifying the biological pathways involved and identifying potential targets for future therapeutic intervention.  

The results suggest that vitamin D metabolites can act as active regulators of cell proliferation, particularly in UV-exposed areas. However, direct clinical evidence remains limited, and the actual effectiveness of photoderivatives in preventive application has yet to be demonstrated.  

Translational studies including controlled clinical trials, VDR polymorphism analyses, and long-term follow-up will be necessary to establish precise recommendations. This approach could lead to a personalized sun prevention medicine, combining vitamin dosage, reasoned photoprotection, and targeted topical treatment.   

Read next: CBD & Sun: innovation beneath the skin