Beyond the Gut: The Microbiota as a Modulator of Skin Health

Abstract

Introduction: The gut–skin axis (GSA) is an emerging concept that describes the bidirectional communication between the gastrointestinal tract and the skin, primarily mediated by the gut and skin microbiota. This interaction influences immune homeostasis, epithelial barrier integrity, and systemic inflammation. Objective:
To explore recent evidence regarding the role of gut microbiota in modulating inflammatory skin diseases and the pathophysiological mechanisms involved, as well as therapeutic implications derived from this connection. Material and Methods:
A narrative review was conducted using scientific literature published between 2018 and 2025, sourced from PubMed, Scopus, and Web of Science. Original articles, reviews, and meta-analyses in English and Spanish were included, with a focus on clinical and experimental studies addressing the gut–skin axis, dysbiosis, and diseases such as psoriasis, atopic dermatitis, acne, and inflammatory bowel disease. Results: Evidence shows that gut dysbiosis can disrupt the production of key microbial metabolites such as short-chain fatty acids (SCFAs), reduce beneficial microbial diversity, and activate systemic inflammatory pathways. These alterations are associated with diseases such as psoriasis, atopic dermatitis, and rosacea. Additionally, receptors such as the vitamin D receptor (VDR) and aryl hydrocarbon receptor (AhR) mediate critical aspects of this communication. Interestingly, external stimuli such as UVB exposure may positively modulate gut microbiota, suggesting a dynamic feedback loop between the skin and the intestine. Conclusions: The gut–skin axis represents a new paradigm in understanding and managing skin and intestinal diseases. Modulating the gut microbiota through diet, prebiotics, probiotics, and physical strategies such as phototherapy could offer novel systemic therapeutic opportunities for promoting skin health.