Information sources and search strategy
Three reviewers independently searched the databases PubMed, Cochrane Library, Science Direct, Ovid, Springer Link, Google Scholar, and ClinicalTrials.gov (https://clinicaltrials.gov). The search algorithm includes: (((((((Postbiotics) OR (Paraprobiotics)) OR (Ghost probiotics)) OR (Parapsychobiotics)) OR (Tyndallized probiotics)) OR (Metabiotics)) OR (Bacterial lysates)) AND (Atopic dermatitis). Some studies involve postbiotics but may not explicitly mention this term or its related terms; instead, they may only describe its inanimation process and the specific microorganism used. Thus, individual probiotic strains reported in the SR on the probiotics of Tan-Lim et al., 23 were also used as search terms for the PubMed database. Search for additional references cited in the screened full-text papers was also performed.24 Search for unpublished articles was done by correspondence with content experts in the field.