Effects of Genetically Modified Food on Gut Microbiota in Animal Models: A Systematic Review

Background: There are some debates about the possible unintended effects of genetically modified (GM) crops on consumer health. The gut microbiota plays an important role in maintaining the health of the host, especially in gastrointestinal diseases. The current review focuses on the studies with the aim of evaluating whether their outcomes indicate any adverse effects of feeding genetically modified (GM) crops on alteration and the count of gut microbiota.Methods: A structured literature search was performed independently by three authors on Scopus, Web of Science, PubMed, and Embase on the 1st of July 2019. In total, 333 publications were obtained by the search strategy, which decreased to 306 after excluding the duplicates. Furthermore, experimental studies that have designed a control group and were written in English were included in the review. After reviewing the full texts, 16 studies were included. To access the quality of articles, we used the Cochrane checklist.Results: Ten publications (62.5%) used 50% or more genetically modified (GM) diet in the treatment group. In 11 studies (68.7%), the duration of animal feeding was 90 days or more. There were no significant differences in the experimental and control groups of both male and female rats on the 90th day; it can be concluded that non-genetically modified (GM) and genetically modified (GM) rice diets did not cause any changes in the gut bacteria. Data analysis of different animal models showed that the most changes in the microbial flora were observed in the chicken and the least in the rat. In the studies in this review, all microbial isolates were anaerobic, and the Lactobacillus and Enterococcus families were common organisms.Conclusion: Based on our literature review, we claim that there is not any significant difference in gut microbiota between the control group and the group with a transgenic diet. The mechanisms of the effects of genetically modified (GM) foods on the gut microbiota in animals should be explicated in future studies. Nevertheless, this study provides valuable information for research on genetically modified (GM) foods and whether they are useful or detrimental to human health.