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.

Background/Aims: It has been largely accepted that dietary habits affect intestinal microbiota composition. In this pilot study, we hypothesized that time-restricted feeding, which can be regarded as a type of intermittent fasting, may have a distinct effect on intestinal microbiota. Ramadan fasting is an excellent model to understand how time-restricted feeding affect the microbiota. Materials and Methods: A total of nine subjects were included in this study during Ramadan, consisting of 17 h of fasting/day during a 29-day period. Stool samples were collected at baseline and the day of the end of Ramadan. 16S rRNA qPCR assay has been performed for quantification of Akkermansia muciniphila, Faecalibacterium prausnitzii, Bifidobacterium spp., Lactobacillus spp., Bacteroides fragilis group, and Enterobacteriaceae. Blood samples were also collected to test for metabolic and nutritional parameters. Results: A significantly increased abundance of A. muciniphila and B. fragilis group was observed in all subjects after Islamic fasting when compared with the baseline levels (p=0.004 and 0.008, respectively). Serum fasting glucose and total cholesterol levels were also significantly reduced in all of the subjects (p<0.01 and p=0.009, respectively). Conclusion: Islamic fasting, which represents intermittent fasting, leads to an increase in A. muciniphila and B. fragilis group, which were considered as healthy gut microbiota members. Although this is a pilot study, which should be tested with larger sample size, there are a very limited number of studies in the literature on fasting and microbiota in human subjects. Thus, our present findings may contribute to the understanding of fasting-gut microbiota interaction.

To compare the beneficial effects of early enteral nutrition (EN) with prebiotic fiber supplementation in patients with severe acute pancreatitis (AP). Thirty consecutive patients with severe AP, who required stoppage of oral feeding for 48 h, were randomly assigned to nasojejunal EN with or without prebiotics. APACHE II score, Balthazar's CT score and CRP were assessed daily during the study period. The median duration of hospital stay was shorter in the study group [10 +/- 4 (8-14) d vs 15 +/- 6 (7-26) d] (P < 0.05). The median value of days in intensive care unit was also similar in both groups [6 +/- 2 (5-8) d vs 6 +/- 2 (5-7) d]. The median duration of EN was 8 +/- 4 (6-12) d vs 10 +/- 4 (6-13) d in the study and control groups, respectively (P > 0.05). Deaths occurred in 6 patients (20%), 2 in the study group and 4 in the control group. The mean duration of APACHE II normalization (APACHE II score < 8) was shorter in the study group than in the control group (4 +/- 2 d vs 6.5 +/- 3 d, P < 0.05). The mean duration of CRP normalization was also shorter in the study group than in the control group (7 +/- 2 d vs 10 +/- 3 d, P < 0.05). Nasojejunal EN with prebiotic fiber supplementation in severe AP improves hospital stay, duration nutrition therapy, acute phase response and overall complications compared to standard EN therapy.

To demonstrate whether there is a relationship between the presence of nonalcoholic fatty liver disease (NAFLD) and the presence and extent of coronary artery disease (CAD). Ninety-two consecutive patients who planned to undergo coronary angiographies (CAG) without known CAD, other than findings of acute coronary syndrome, were enrolled in this study. Abdominal ultrasonography was performed before the CAG to detect NAFLD. CAD was defined as a stenosis of at least 50% in at least one major coronary artery. The extent of CAD was measured according to the number of major coronary artery/arteries affected by CAD. All the risk factors for CAD were included in a binary logistic regression model. Forward, backward, or step-wise selections were not used. P<0.05 was accepted as being significant. Sixty-five of the 92 patients (70.7%) were detected, by abdominal ultrasonography, to have fatty liver and 43 patients out of 92 (46.7%) were detected, by CAG, to have significant CAD. According to the results of logistic regression analysis, the presence of NAFLD independently increased the risk for CAD, as seen in CAG [odds ratio (OR), 95% confidence interval (CI): 6.73 (1.14–39.61); P=0.035]; this was despite factoring in the other risk factors for CAD and the components of metabolic syndrome. NAFLD was more commonly found in patients as the extent of CAD increased (P=0.001). The presence of NAFLD is independently associated with the presence and extent of CAD. Future studies are needed to explain the mechanisms of this relationship.