Modification of Gut Microbiome by Cereal and Pseudocereal Consumption: A Systematic Review

CONTEXT: Diet profoundly shapes the composition and function of the gut microbiome. Cereals and pseudocereals, as part of a healthy diet, may have significant potential in the modulation of the gut microbiome. OBJECTIVE: This review aimed to systematically analyze the evidence from human intervention studies that examine the effects of cereal and pseudocereal consumption on the gut microbiome composition, diversity, and metabolites. DATA SOURCES: Three electronic databases were searched from database inception to May 2025: PubMed/Medline, the Web of Science, and Cochrane. This review included randomized controlled trials with parallel and crossover designs, controlled nonrandomized intervention studies, and single-arm pre-post intervention studies. In addition, only English-language articles reporting changes in the gut microbiome and bacterial fermentation metabolites associated with dietary intake of cereal and pseudocereals in adult individuals (>18 years) were included. DATA EXTRACTION: Basic information regarding the methodological characteristics of the included studies and the outcome measures was recorded. DATA ANALYSIS: A total of 9670 articles were analyzed, of which 48 articles were ultimately included. The majority of the included studies (41/48) showed that cereal consumption was associated with significant changes in the gut microbiome composition. In terms of microbial diversity, only 4 of 29 studies showed significant increases in the α-diversity of the gut microbiome. Among the 28 studies analyzing short-chain fatty acid levels, 12 studies reported significant changes in the levels of short-chain fatty acids. CONCLUSIONS: Although the importance of daily cereal consumption in modulating the gut microbiome is recognized, well-designed new studies are needed to identify the most effective types of cereal or pseudocereals, and the amount that is adequate to achieve the desired modulation.