Oral Postbiotics as a Therapeutic Strategy for Atopic Dermatitis: A Systematic Review of Randomized Controlled Trials.

Atopic dermatitis (AD) is a prevalent chronic skin disease affecting all age groups. The connection with the gut microbiome led to oral probiotics as a therapeutic strategy. However, being viable microorganisms, probiotics might present risks. Thus, non-viable postbiotics have been considered as an alternative. We aimed to evaluate the efficacy of oral postbiotics for managing symptoms of AD in pediatric and adult patients. A systematic review was conducted following PRISMA guidelines. Nine randomized controlled trials assessing the effects of non-viable spp. administered orally to patients diagnosed with AD were included in the review, in which 512 subjects were evaluated after the intervention. Most studies allowed the concomitant usage of corticosteroids. Three studies focused on adults and indicated symptom improvement. In contrast, three out of six trials evaluating pediatric patients did not report postbiotics-favoring results. The dosage seems to be relevant for outcome determination. Two trials compared postbiotics with their viable analogs, and only one reported positive results in both groups. Postbiotics-associated shifts in gut microbial communities were reported in one trial. Mild adverse effects were detected by a single study. The overall results suggested that postbiotics might be successfully used as adjuvant AD therapy in adults. Thus far, data do not indicate efficacy in pediatric patients. Standardizing nomenclatures and experimental procedures, as well as expanding the studies to more geographic locations and assessing comprehensively the effects on the gut microbiome would provide better perspectives of postbiotics as a therapeutic option for AD.