Remodeling of the gut microbiome during Ramadan-associated intermittent fasting

Background: Intermittent fasting is a popular dietary intervention with perceived relatively easy compliance and is linked to various health benefits, including weight loss and improvement in blood glucose concentrations. The mechanistic explanations underlying the beneficial effects of intermittent fasting remain largely obscure but may involve alterations in the gut microbiota. Objectives: We sought to establish the effects of 1 mo of intermittent fasting on the gut microbiome. Methods: We took advantage of intermittent fasting being voluntarily observed during the Islamic faith-associated Ramadan and sampled feces and blood, as well as collected longitudinal physiologic data in 2 cohorts, sampled in 2 different years. The fecal microbiome was determined by 16S sequencing. Results were contrasted to age- and body weight-matched controls and correlated to physiologic parameters (e.g., body mass and calorie intake). Results: We observed that Ramadan-associated intermittent fasting increased microbiome diversity and was specifically associated with upregulation of the Clostridiales order-derived Lachnospiraceae [no fasting 24.6 +/- 13.67 compared with fasting 39.7 +/- 15.9 in relative abundance (%); linear discriminant analysis = 4.9, P < 0.001 by linear discriminant analysis coupled with effect size measurements] and Ruminococcaceae [no fasting 13.4 +/- 6.9 compared with fasting 23.2 +/- 12.9 in relative abundance (%); linear discriminant analysis = 4.7, P < 0.001 by linear discriminant analysis coupled with effect size measurements] bacterial families. Microbiome composition returned to baseline upon cessation of intermittent feeding. Furthermore, changes in Lachnospiraceae concentrations mirrored intermittent fasting-provoked changes in physiologic parameters. Conclusions: Intermittent fasting provokes substantial remodeling of the gut microbiome. The intermittent fasting-provoked upregulation of butyric acid-producing Lachnospiraceae provides an obvious possible mechanistic explanation for health effects associated with intermittent fasting.

Automated summary

Intermittent fasting, particularly observed during Ramadan, was found to increase gut microbiome diversity and upregulate specific bacterial families such as Lachnospiraceae and Ruminococcaceae. These changes in microbiome composition returned to baseline after cessation of intermittent feeding, and alterations in Lachnospiraceae concentrations were correlated with changes in physiological parameters provoked by intermittent fasting. The study suggests that the upregulation of butyric acid-producing Lachnospiraceae may play a role in the health benefits associated with intermittent fasting.