Table 1.

Search strategy of the systematic review.

Database	Search strategy
SCOPUS	(TITLE-ABS-KEY (“celiac disease” OR “coeliac”) AND TITLE-ABS-KEY (“gut microbiota” OR “bacteria” OR “microbes” OR “microbiome” OR “microbiota dysbiosis” OR “metagenome” OR “metabolomics” OR “fecal microbiota” OR “intestinal microbiota” OR “duodenal microbiota”)
PUBMED	(“celiac disease” [mh] OR “coeliac” [mh]) AND (“gut microbiota” OR “bacteria” OR “microbes” OR “microbiome” OR “microbiota dysbiosis” OR “metagenome” OR “metabolomic” OR “fecal microbiota” OR “intestinal microbiota” OR “duodenal microbiota”), showing the search details: “celiac disease” [mh] AND (“gut microbiota” [All Fields] OR “bacteria” [All Fields] OR “microbes” [All Fields] OR “microbiome” [All Fields] OR “microbiota dysbiosis” [All Fields] OR “metagenome” [All Fields] OR “metabolomics” [All Fields] OR “fecal microbiota” [All Fields] OR “intestinal microbiota” [All Fields] OR “duodenal microbiota” [All Fields])
COCHRANE	*“celiac disease” OR “coeliac” in Title Abstract Keyword AND “gut microbiota” OR “bacteria” OR “microbes” OR “microbiome” OR “microbiota dysbiosis” OR “metagenome” OR “metabolomics” OR “fecal microbiota” OR “intestinal microbiota” OR “duodenal microbiota” in Abstract - (Word variations have been searched)
OVID	(celiac disease OR coeliac) AND (gut microbiota OR bacteria OR microbes OR microbiome OR microbiota dysbiosis OR metagenome OR metabolomic OR fecal microbiota OR intestinal microbiota OR duodenal microbiota). The exact search details were: (celiac disease or coeliac) and (gut microbiota or bacteria or microbes or microbiome or microbiota dysbiosis or metagenome or metabolomic or fecal microbiota or intestinal microbiota or duodenal microbiota) [mp = title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, organism supplementary concept word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms] {Including Related Terms}.
WEB OF SCIENCE	1- (TS = (celiac disease OR coeliac disease)) AND LANGUAGE: (English) AND DOCUMENT TYPES: (Article); 2- (ALL = (gut microbiota OR bacteria OR microbes OR microbiome OR microbiota dysbiosis OR metagenome OR metabolomic OR fecal microbiota OR intestinal microbiota OR duodenal microbiota)) AND LANGUAGE: (English) AND DOCUMENT TYPES: (Article); 3- #2 AND #1.