Mehran Rahimlou - Department of Nutrition, School of Medicine, Zanjan University of Medical Sciences,Zanjan, Iran
Seyedeh Neda Mousavi - Department of Nutrition, School of Medicine, Zanjan University of Medical Sciences,Zanjan, Iran
Nazila Hasaniani - Department of Nutrition, School of Medicine, Zanjan University of Medical Sciences,Zanjan, Iran

Background and purpose: In recent years, intermittent fasting has gained popularity in the health and wellnessin the world. There are numerous types of intermittent fasting (IF), all of which involve fasting periods that lastlonger than an overnight fast and involve limited meal time-windows, with or without calorie restriction. The objective of this review is to summarize the current evidence for the effects of Ramadan and non-Ramadanintermittent fasting on gut microbiome.Materials and methods: We explored Pubmed, Scopus, Web of Science and Google Scholar according to thePRISMA criteria (Preferred Reporting Items for Systematic reviews and Meta-Analysis). Animal and humanstudies were screened and reviewed separately by two researchers.Results: Twenty-eight studies were selected after screening. Some of the studies were performed on animalmodels and some on humans. The results of these studies showed different evidence of the effect of fasting dietson the gut microbiota such as increasing microbial diversity, reducing inflammation, and increasing theproduction of beneficial microbial compounds known as short chain fatty acids (SCFAs). Many beneficialbacteria, such as Lactobacillus and Bifidobacterium, had significant shifts in individuals on fasting diets.However, some studies have reported adverse effects of fasting diets on the structure of the microbiome.Conclusion: In general, most studies have seen favorable results following adherence from the fasting diets onthe intestinal microbiome. However, because more studies have been done on animal models, more human studiesare needed to prove the results.

Fasting; Intermediate Fasting; Ramadan; Gut microbiome; Review