Dietary composition and fasting regimens differentially impact gut microbiome and short-chain fatty acid profile in a Pakistani cohort

Farzana Gul¹Hilde Herrema²Aqsa Ameer¹Mark Davids²Arshan Nasir¹Konstantinos Gerasimidis³Umer Zeeshan Ijaz^4*Sundus Javed¹

• ¹Department of Biosciences, COMSATS University, Islamabad, Pakistan
• ²Department of Experimental Vascular Medicine, Amsterdam University Medical Centers, Amsterdam, Netherlands
• ³School of Medicine, Dentistry & Nursing, Glasgow Royal Infirmary, Glasgow, United Kingdom
• ⁴University of Glasgow, Glasgow, United Kingdom

Purpose Fasting is known to have beneficial effects on human physiology and health due to changes in gut microbiota and its associated metabolites. We investigated the effects of intermittent and Ramadan fasting on gut microbial composition, diversity and Short Chain Fatty Acids (SCFA) profile in Pakistani population. Methods Paired fecal samples, a total of 29 for Ramadan fasting (divided into three groups, before, after completion, and after three months) and 22 for intermittent fasting (divided into two groups, day 1 and day 10) were collected for both 16S rRNA microbiome profiling and SCFA analysis. Study volunteers also provided a detailed questionnaire with dietary regimen prefasting and during the fasting period. Descriptive statistics were applied to ascertain variations in gut microbiome and SCFAs attributable to changes in food consumption during fasting period. Results Ramadan fasting increased the bacterial taxonomic and functional diversity and decreased abundance of certain harmful microbes such as Blautia, Haemophilus, Desulfovibrio, Lachnoclostridium and Porphyromonas. Intermittent fasting has showed increased abundance of Prevotella, Lactobacillus and Anaerostipes. Ramadan fasting has also led to significant increase in SCFAs including C7, iC4 and iC6 accounting for variability in microbial composition and phylogeny respectively. In intermittent fasting, C5, iC5 and iC6 contributed to variability in microbial composition, phylogeny and function respectively. Conclusion Both fasting regimens impact gut microbiome and metabolic signatures but Ramadan fasting showed more drastic effect due to the 30 day compliance period and water restriction as compared to intermittent fasting. Ramadan fasting also improves the metabolic health by increasing the abundance of SCFA producing microbes. With Ramadan fasting most microbial taxa reverted to its prefasting state after resumption of normal feeding patterns with few exceptions, indicating impact on microbial niche creation with prolonged fasting regimens that benefit Enterococcus, Turibacter and Klebsiella colonization. Dietary regimen adopted during fasting period especially consumption of high fat content food items accounted for persistent gut microbial changes.