Gut microbiota-skin axis in the treatment of psoriasis and atopic dermatitis with the promotion of gut health: a systematic review

Introduction: Psoriasis is a chronic inflammatory dermatological condition that affects approximately 60 million individuals worldwide, with recurrence rates between 0.1% and 1.5% after conventional treatments. Atopic dermatitis (AD) is a prevalent chronic inflammatory skin disease associated with genetic and environmental factors, characterized primarily by an allergic immune response to environmental antigens with increased levels of immunoglobulin E (IgE). The gut microbiota is essential for immune system activation and the treatment of these diseases. Objective: To investigate the gut microbiota-skin axis in the treatment of atopic dermatitis and psoriasis through the promotion of gut health. Methods: The PRISMA Platform systematic review rules were followed. The search was carried out from July to August 2025 in the Scopus, Embase, PubMed, Science Direct, Scielo, and Google Scholar databases. Study quality was based on the GRADE instrument, and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 131 articles were found, and 28 articles were evaluated in full, and 17 were included and developed in the present systematic review study. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 24 studies with a high risk of bias and 25 studies that did not meet GRADE and AMSTAR-2. Most studies showed homogeneity in their results, with X2=77.6 %>50%. It was concluded that the gut microbiota has enormous metabolic capacity along the gut-skin axis. Dietary or microbiota metabolites are accessible to the skin. Therefore, after defining key open questions about the nature of these metabolites, their detection, and the skin changes they can induce, understanding these pathways will lead to new therapeutic strategies that target one organ to improve the health of another. Probiotics and prebiotics are microbiota management tools for treating psoriasis and atopic dermatitis.