It has been largely accepted that dietary changes have an effect on gut microbial composition. In this pilot study we hypothesised that Ramadan fasting, which can be considered as a type of time-restricted feeding may lead to changes in gut microbial composition and diversity. A total of 9 adult subjects were included in the study. Stool samples were collected before (baseline) and at the end of the Ramadan fasting (after 29 days). Following the construction of an 16S rRNA amplicon library, the V4 region was sequenced using the Illumina Miseq platform. Microbial community analysis was performed using the QIIME program. A total of 27,521 operational taxonomic units (OTUs) with a 97% similarity were determined in all of the samples. Microbial richness was significantly increased after Ramadan according to observed OTU results (P=0.016). No significant difference was found in terms of Shannon index or phylogenetic diversity metrics of alpha diversity. Microbial community structure was significantly different between baseline and after Ramadan samples according to unweighted UniFrac analysis (P=0.025). LEfSe analysis revealed that Butyricicoccus, Bacteroides, Faecalibacterium, Roseburia, Allobaculum, Eubacterium, Dialister and Erysipelotrichi were significantly enriched genera after the end of Ramadan fasting. According to random forest analysis, the bacterial species most affected by the Ramadan fasting was Butyricicoccus pullicaecorum. Despite this is a pilot study with a limited sample size; our results clearly revealed that Ramadan fasting, which represents an intermittent fasting regime, leads to compositional changes in the gut microbiota.

Vagus nerve assessment via ultrasonography in irritable bowel syndrome. Are there any changes of dimension in the vagus nerve?

Gut microbiota composition and function are major areas of research for functional gastrointestinal disorders. There is a connection between gastrointestinal tract and central nervous system and this is mediated by neurotransmitters, inflammatory cytokines, the vagus nerve and the hypothalamic-pituitary-adrenal axis. Functional gastrointestinal disorders are prevalent diseases affecting more than one third of the population. The etiology of these disorders is not clarified. Visceral hyperalgesia is the main hypothesis for explaining clinical symptoms, however gut-brain axis disorder is a new terminology for functional disorders. In this review, microbiota-gut-brain axis connection pathways and related disorders are discussed. Antibiotics are widely used in developed countries and recent evidence indicates antibiotic-induced dysbiosis as an important factor for functional disorders. Antibiotics exert negative effects on gut microbiota composition and functions. Antibiotic-induced dysbiosis is a major factor for occurrence of post-infectious irritable bowel syndrome. Cognitive and mood disorders are also frequent in functional gastrointestinal disorders. Animal and human trials show strong evidence for the causal relationship between gut microbiota and brain functions. Therapeutic implications of these newly defined pathogenic pathways are also discussed.

The gastrointestinal microbiota protects hosts from enteric infections; while antibiotics, by altering the microbiota, may diminish this protection. We show that after early-life exposure to antibiotics host susceptibility to enhanced Citrobacter rodentium-induced colitis is persistent and that this enhanced disease susceptibility is transferable by the antibiotic-altered microbiota. These results strongly suggest that early-life antibiotics have long-term consequences on the gut microbiota and enteropathogen infection susceptibility.