Ramadan Fasting Leads to Shifts in Human Gut Microbiota Structured by Dietary Composition

Metagenomics Analysis Reveals the Composition and Functional Differences of Fecal Microbiota in Wild, Farm, and Released Chinese Three-Keeled Pond Turtles (Mauremys reevesii)

The intestine of living organisms harbors different microbiota associated with the biological functioning and health of the host and influences the process of ecological adaptation. Here, we studied the intestinal microbiota's composition and functional differences using 16S rRNA and metagenomic analysis in the wild, farm, and released Chinese three-keeled pond turtle (Mauremys reevesii). At the phylum level, Bacteroidota dominated, followed by Firmicutes, Fusobacteriota, and Actinobacteriota in the wild group, but Chloroflexi was more abundant in the farm and released groups. Moreover, Chryseobacterium, Acinetobacter, Comamonas, Sphingobacterium, and Rhodobacter were abundant in the released and farm cohorts, respectively. Cetobacterium, Paraclostridium, Lysobacter, and Leucobacter showed an abundance in the wild group. The Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed that the relative abundance of most pathways was significantly higher in the wild turtles (carbohydrate metabolism, lipid metabolism, metabolism of cofactors, and vitamins). The comprehensive antibiotic resistance database (CARD) showed that the antibiotic resistance gene (ARG) subtype macB was the most abundant in the farm turtle group, while tetA was higher in the wild turtles, and srpYmcr was higher in the released group. Our findings shed light on the association between the intestinal microbiota of M. reevesii and its habitats and could be useful for tracking habitats to protect and conserve this endangered species.

The effects of time-restricted eating and Ramadan fasting on gut microbiota composition: a systematic review of human and animal studies

CONTEXT

It is well known that the microbiome undergoes cyclical diurnal rhythms. It has thus been hypothesized that meal timing may affect gut microbial composition, function, and host health.

OBJECTIVE

This review aims to examine the effects of time-restricted eating (TRE) and Ramadan fasting (RF) on the composition of the gut microbiota in animal and human studies. The associations between composition of microbiota and host metabolic parameters are also examined.

DATA SOURCES

A search was performed on the PubMed, Cochrane, Scopus, and Web of Science databases up to December 31, 2022. The search strategy was performed using the Medical Subject Heading (MeSH) terms "intermittent fasting" and "gastrointestinal microbiome" and the key words "Ramadan fasting" and "microbes."

DATA EXTRACTION

Seven human studies (4 TRE and 3 RF) and 9 animal studies (7 TRE, 2 RF-like) were retrieved.

DATA ANALYSIS

TRE and RF in human studies lead to an increase in gut microbial community alpha-diversity. In animal studies (both TRE and RF-like), fasting is not associated with improved alpha-diversity, but enhancement of microbial fluctuation is observed, compared with high-fat diet ad libitum groups. Within Firmicutes and Bacteroidetes phyla, no specific direction of changes resulting from fasting are observed in both animals and human. After TRE or RF, a greater abundance of the Faecalibacterium genus is observed in human studies; changes in Lactobacillus abundance are found in animal studies; and increases in Akkermansia are seen both in humans and in animals fed a feed-pellet diet. Only 2 human studies show a beneficial correlation between microbiota changes and host metabolic (HDL cholesterol) or anthropometric parameters (body mass index).

CONCLUSIONS

These findings support the importance of both regimens in improving the gut microbiota composition. However, based on results of animal studies, it can be suggested that diet remains the essential factor in forming the microbiota's environment.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021278918.

Intermittent fasting modulates human gut microbiota diversity in a phenotype-dependent manner: a systematic review

Cumulative evidence suggests that intermittent fasting (IF) has beneficial effects on human metabolic health. It has been indicated that its impact on the gut microbiota may mediate these beneficial effects. As a result, we hypothesized that IF may impact the human gut microbiota. A systematic review was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol using the PubMed, Scopus, and CINAHL databases. We registered our systematic review protocol in PROSPERO under registration number CRD42021270050. Human intervention studies published until April 30, 2023, were included. The quality of the included studies was assessed using National Institutes of Health (NIH) quality assessment study tools for intervention studies. The search in the database returned 166 studies, of which 13 matched all criteria for the final qualitative analysis. The body of evidence suggests that IF modulates human gut microbiota alpha and beta diversity in lean (relatively healthy) and relatively healthy overweight/obese individuals but not in individuals with metabolic syndrome. Furthermore, IF also alters human gut microbiota composition in all phenotypes. Of interest, the gut microbiota taxa or microbial metabolites after an IF intervention are associated with metabolic markers. According to this review, IF influences the diversity and taxonomic levels of the human gut microbiota. Individual metabolic phenotypes may alter the effect of IF on the diversity and taxonomic levels of the gut microbiota.

Mind over Microbes: Investigating the Interplay between Lifestyle Factors, Gut Microbiota, and Brain Health

BACKGROUND

The gut microbiota (GM) of the human body comprises several species of microorganisms. This microorganism plays a significant role in the physiological and pathophysiological processes of various human diseases.

METHODS

The literature review includes studies that describe causative factors that influence GM. The GM is sensitive to various factors like circadian rhythms, environmental agents, physical activity, nutrition, and hygiene that together impact the functioning and composition of the gut microbiome. This affects the health of the host, including the psycho-neural aspects, due to the interconnectivity between the brain and the gut. Hence, this paper examines the relationship of GM with neurodegenerative disorders in the context of these aforesaid factors.

CONCLUSION

Future studies that identify the regulatory pathways associated with gut microbes can provide a causal link between brain degeneration and the gut at a molecular level. Together, this review could be helpful in designing preventive and treatment strategies aimed at GM, so that neurodegenerative diseases can be treated.

The impact of intermittent fasting on gut microbiota: a systematic review of human studies

Background

Intermittent fasting (IF) has gained popularity in interventions targeting overweight, obesity and metabolic syndrome. IF may affect the gut microbiome composition and therefore have various effects on gut microbiome mediated functions in humans. Research on the effects of IF on human gut microbiome is limited. Therefore, the objective of this systematic review was to determine how different types of IF affect the human gut microbiome.

Methods

A literature search was conducted for studies investigating the association of different types of IF and gut microbiota richness, alpha and beta diversity, and composition in human subjects. Databases included Cochrane Library (RRID:SCR_013000), PubMed (RRID:SCR_004846), Scopus (RRID:SCR_022559) and Web of Science (RRID:SCR_022706). A total of 1,332 studies were retrieved, of which 940 remained after removing duplicates. Ultimately, a total of 8 studies were included in the review. The included studies were randomized controlled trials, quasi-experimental studies and pilot studies implementing an IF intervention (time-restricted eating, alternate day fasting or 5:2 diet) in healthy subjects or subjects with any disease.

Results

Most studies found an association between IF and gut microbiota richness, diversity and compositional changes. There was heterogeneity in the results, and bacteria which were found to be statistically significantly affected by IF varied widely depending on the study.

Conclusion

The findings in this systematic review suggest that IF influences gut microbiota. It seems possible that IF can improve richness and alpha diversity. Due to the substantial heterogeneity of the results, more research is required to validate these findings and clarify whether the compositional changes might be beneficial to human health.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021241619.

Gut microbial ecology and exposome of a healthy Pakistani cohort

BACKGROUND

Pakistan is a multi-ethnic society where there is a disparity between dietary habits, genetic composition, and environmental exposures. The microbial ecology of healthy Pakistani gut in the context of anthropometric, sociodemographic, and dietary patterns holds interest by virtue of it being one of the most populous countries, and also being a Lower Middle Income Country (LMIC).

METHODS

16S rRNA profiling of healthy gut microbiome of normo-weight healthy Pakistani individuals from different regions of residence is performed with additional meta-data collected through filled questionnaires. The current health status is then linked to dietary patterns through [Formula: see text] test of independence and Generalized Linear Latent Variable Model (GLLVM) where distribution of individual microbes is regressed against all recorded sources of variability. To identify the core microbiome signature, a dynamic approach is used that considers into account species occupancy as well as consistency across assumed grouping of samples including organization by gender and province of residence. Fitting neutral modeling then revealed core microbiome that is selected by the environment.

RESULTS

A strong determinant of disparity is by province of residence. It is also established that the male microbiome is better adapted to the local niche than the female microbiome, and that there is microbial taxonomic and functional diversity in different ethnicities, dietary patterns and lifestyle habits. Some microbial genera, such as, Megamonas, Porphyromonas, Haemophilus, Klebsiella and Finegoldia showed significant associations with consumption of pickle, fresh fruits, rice, and cheese. Our analyses suggest current health status being associated with the diet, sleeping patterns, employment status, and the medical history.

CONCLUSIONS

This study provides a snapshot of the healthy core Pakistani gut microbiome by focusing on the most populous provinces and ethnic groups residing in predominantly urban areas. The study serves a reference dataset for exploring variations in disease status and designing personalized dietary and lifestyle interventions to promote gut health, particularly in LMICs settings.

Comparative analysis of fasting effects on the cecum microbiome in three guinea pig breeds: Andina, Inti, and Peru

Guinea pigs have historically been used as a food source and are also an important model for studying the human intestines. Fasting is the act of temporarily stopping the intake of food. This process can alter the microbiota of various animals. This study is the first to investigate the impact of fasting on the cecum microbiome of three guinea pig breeds. We investigated the impact of fasting on the microbiome population structure in the cecum of three guinea pig breeds. This was done by sequencing and analyzing the V4 hypervariable region of the 16S rRNA gene in bacterial communities found in cecum mucosa samples. To achieve this, we established two treatment groups (fasting and fed), for each of the three guinea pig breeds: Andina, Inti, and Peru. The study involved twenty-eight guinea pigs, which were divided into the following groups: Andina-fed (five), Andina-fasting (five), Inti-fed (four), Inti-fasting (five), Peru-fed (five), and Peru-fasting (four). The results indicated a significant difference in beta diversity between the treatment groups for the Peru breed (P-value = 0.049), but not for the treatment groups of the Andina and Inti breeds. The dominant phyla across all groups were Firmicutes and Bacteroidetes. We observed variations in the abundance of different taxa in the cecum microbiota when comparing the treatment groups for each breed. Additionally, there was a higher number of unique taxa observed in the fasting groups compared to the fed groups. We discovered that the genus Victivallis was the only one present in all fasting groups across all breeds. Despite the findings, the resilience of the gut microbiome was not challenged in all three breeds, which can lead to disruptive changes that may affect the overall maintenance of the cecum microbiome. Based on the observed differences in the treatment groups of the Peru breed, it can be suggested that fasting has a greater impact on this particular breed.

The Beneficial Effects of Dietary Interventions on Gut Microbiota-An Up-to-Date Critical Review and Future Perspectives

Different dietary interventions, especially intermittent fasting, are widely used and promoted by physicians; these regimens have been studied lately for their impact on the gut microbiota composition/function and, consequently, on the general physiopathological processes of the host. Studies are showing that dietary components modulate the microbiota, and, at the same time, the host metabolism is deeply influenced by the different products resulting from nutrient transformation in the microbiota compartment. This reciprocal relationship can potentially influence even drug metabolism for chronic drug regimens, significantly impacting human health/disease. Recently, the influence of various dietary restrictions on the gut microbiota and the differences between the effects were investigated. In this review, we explored the current knowledge of different dietary restrictions on animal and human gut microbiota and the impact of these changes on human health.

Time-restricted eating for chronodisruption-related chronic diseases

The circadian timing system enables organisms to adapt their physiology and behavior to the cyclic environmental changes including light-dark cycle or food availability. Misalignment between the endogenous circadian rhythms and external cues is known as chronodisruption and is closely associated with the development of metabolic and gastrointestinal disorders, cardiovascular diseases, and cancer. Time-restricted eating (TRE, in human) is an emerging dietary approach for weight management. Recent studies have shown that TRE or time-restricted feeding (TRF, when referring to animals) has several beneficial health effects, which, however, are not limited to weight management. This review summarizes the effects of TRE/TRF on regulating energy metabolism, gut microbiota and homeostasis, development of cardiovascular diseases and cancer. Furthermore, we will address the role of circadian clocks in TRE/TRF and propose ways to optimize TRE as a dietary strategy to obtain maximal health benefits.

Effects of Ramadan intermittent fasting on gut microbiome: is the diet key?

Much research has been conducted regarding the impact of diet on the gut microbiota. However, the effects of dietary habits such as intermittent fasting are unclear. This study aimed to investigate the effect of intermittent fasting during Ramadan on the gut microbiota. The study was conducted on 12 healthy adult individuals who practiced fasting 17 h per day for 29 consecutive days during the month of Ramadan. To determine the dietary intake of individuals, a 3-day dietary record was kept at the beginning and end of the study. Reads that passed quality filtering were clustered, and custom-prepared 16S rRNA gene regions of bacteria associated with the human microbiome were used as a reference. Consensus sequences were created, and genus-level taxonomic annotations were determined using a sequence identity threshold of 95%. The correlations between the dietary intake measurements of the participants and the respective relative abundance of bacterial genera were investigated. The results showed that Firmicutes were higher in abundance in the gut microbiota before fasting among participants, while they were significantly lower in abundance at the end of Ramadan fasting (p < 0.05). Proteobacteria were significantly higher in abundance at the end of the month of Ramadan (p < 0.05). Fasting was associated with a significant decrease in levels of seven genera: Blautia, Coprococcus, Dorea, Faecalicatena, Fusicatenibacter, Lachnoclostridium, and Mediterraneibacter. Conversely, the abundances of two bacterial genera were enhanced at the end of the fasting month: Escherichia and Shigella. The results of the dietary intake analysis showed that a negative correlation was detected for three comparisons: Ihubacter and protein (rho = -0.54, p = 0.0068), Fusicatenibacter and vegetables (rho = -0.54, p = 0.0042), and Intestinibacter and nuts (rho = -0.54, p-value = 0.0065). The results suggest that even when the fasting period during Ramadan is consistent, the types of food consumed by individuals can affect the gut microbiota.

Impact of Intermittent Fasting on the Gut Microbiota: A Systematic Review

Obesity often results in severe negative health consequences and represents a growing issue for global health. Reducing food intake is a crucial factor for weight loss. Intermittent fasting is a relatively new intervention that contributes to weight reduction. Considering the intimate relationship between obesity and inflammatory pathologies with gut microbiota alterations, a systematic review of the literature was herein conducted to elucidate the relationship between time-restricted food intake and gut microbiota diversity in humans. Searches are carried out in three databases (PubMed, MedLine/OVID, and Academic Search Complete) between April 2019 and April 2022. Nine studies (all with longitudinal design) were identified as eligible by presenting data about the impact of intermittent fasting schemes on gut microbiota. At the phylum level, Firmicutes and Bacteroidetes increase throughout follow-ups, while 16 bacteria genera change their abundance in response to intermittent fasting. Finally, some genera associated with clinical predictors such as weight change, abdominal circumference, and metabolic variables were reported. Changes induced by fasting schemes positively impact the diversity and abundance of gut microbiota and the biomarkers described here. However, the changes previously reported have been studied in short periods and some return to their basal state after fasting intervention.

Gut microbiota and transcriptome dynamics in every-other-day fasting are associated with neuroprotection in rats with spinal cord injury

Introduction

Every-other-day fasting (EODF) is a classical intermittent fasting (IF) mode with neuroprotective effects that promotes motor function recovery after spinal cord injury (SCI) in rats. However, its dynamic effects on the gut microbiota and spinal cord transcriptome remain unknown.

Methods

In this study, 16S rRNA sequencing and RNA-seq analysis were used to investigate the effects of ad libitum (AL) and EODF dietary modes on the structural characteristics of rat gut microbiota in rats and the spinal cord transcriptome at various time points after SCI induction.

Results

Our results showed that both dietary modes affected the bacterial community composition in SCI rats, with EODF treatment inducing and suppressing dynamic changes in the abundances of potentially anti-inflammatory and pro-inflammatory bacteria. Furthermore, the differentially expressed genes (DEGs) enriched after EODF intervention in SCI rats were associated with various biological events, including immune inflammatory response, cell differentiation, protein modification, neural growth, and apoptosis. In particular, significant spatiotemporal differences were apparent in the DEGs associated with neuroprotection between the EODF and AL interventions. These DGEs were mainly focused on days 1, 3, and 7 after SCI. The relative abundance of certain genera was significantly correlated with DEGs associated with neuroprotective effects in the EODF-SCI group.

Discussion

Our results showed that EODF treatment may exert neuroprotective effects by modulating the transcriptome expression profile following SCI in rats. Furthermore, gut microbiota may be partially involved in mediating these effects.

A nexus of dietary restriction and gut microbiota: Recent insights into metabolic health

In recent times, dietary restriction (DR) has received considerable attention for its promising effects on metabolism and longevity. Previous studies on DR have mainly focused on the health benefits produced by different restriction patterns, whereas comprehensive reviews of the role of gut microbiota during DR are limited. In this review, we discuss the effects of caloric restriction, fasting, protein restriction, and amino acid restriction from a microbiome perspective. Furthermore, the underlying mechanisms by which DR affects metabolic health by regulating intestinal homeostasis are summarized. Specifically, we reviewed the impacts of different DRs on specific gut microbiota. Additionally, we put forward the limitations of the current research and suggest the development of personalized microbes-directed DR for different populations and corresponding next-generation sequencing technologies for accurate microbiological analysis. DR effectively modulates the composition of the gut microbiota and microbial metabolites. In particular, DR markedly affects the rhythmic oscillation of microbes which may be related to the circadian clock system. Moreover, increasing evidence supports that DR profoundly improves metabolic syndrome, inflammatory bowel disease, and cognitive impairment. To summarize, DR may be an effective and executable dietary manipulation strategy for maintaining metabolic health, however, further investigation is needed to elucidate the underlying mechanisms.

A Scoping Review of the Relationship between Intermittent Fasting and the Human Gut Microbiota: Current Knowledge and Future Directions

Intermittent fasting (IF) has been promoted as an alternative to dietary caloric restriction for the treatment of obesity. IF restricts the amount of food consumed and improves the metabolic balance by synchronizing it with the circadian rhythm. Dietary changes have a rapid effect on the gut microbiota, modulating the interaction between meal timing and host circadian rhythms. Our paper aims to review the relationships between IF and human gut microbiota. In this study, the primary area of focus was the effect of IF on the diversity and composition of gut microbiota and its relationship with weight loss and metabolomic alterations, which are particularly significant for metabolic syndrome characteristics. We discussed each of these findings according to the type of IF involved, i.e., time-restricted feeding, Ramadan fasting, alternate-day fasting, and the 5:2 diet. Favorable metabolic effects regarding the reciprocity between IF and gut microbiota changes have also been highlighted. In conclusion, IF may enhance metabolic health by modifying the gut microbiota. However additional research is required to draw definitive conclusions about this outcome because of the limited number and diverse designs of existing studies.

Implications of Ramadan Fasting in the Setting of Gastrointestinal Disorders

Intermittent fasting is an increasingly popular dieting technique with many well-studied benefits, such as permitting weight loss in obese patients, lowering low-density lipoprotein cholesterol (LDL-C) levels and triglyceride levels, and optimizing circadian rhythms. A special type of intermittent fasting occurs during Ramadan, when Muslims worldwide fast daily from dawn to sunset for a month. Ramadan fasting has demonstrated several health benefits, including improving the gut microbiome, modifying gut hormone levels, and lowering proinflammatory markers such as cytokines and blood lipids. Although fasting has many health benefits, fasting during Ramadan may aggravate chronic medical conditions. We aim to review the literature devoted to Ramadan fasting and its effects on Muslim patients with gastrointestinal (GI) disorders, such as Inflammatory bowel disease (IBD), peptic ulcer disease (PUD), upper GI bleeding (UGIB), gastroesophageal reflux disease (GERD), and liver conditions. We will discuss recommendations for diet and medication compliance during Ramadan in the recommended pre-Ramadan counseling sessions. In this study, we used PubMed to research journals using the key terms "Ramadan," "intermittent fasting," and "gastrointestinal diseases." The current literature studying the impact of Ramadan on gastrointestinal disorders shows that patients with IBD have a minimal risk of disease exacerbation, although older men with ulcerative colitis (UC) were more prone to exacerbation during fasting. Patients with duodenal ulcers were at a higher risk of hemorrhage after Ramadan fasting. Although with mixed results, studies show patients with liver disease demonstrated improvements in liver enzymes, cholesterol, and bilirubin after Ramadan. Physicians should offer pre-Ramadan counseling to educate patients on the risks of fasting and encourage shared decision-making. To facilitate more definitive discussions between the physician and a Muslim patient, clinicians should seek a deeper understanding of how Ramadan fasting affects certain health conditions and offer accommodations, such as diet and medication adjustments.

Impact of caloric restriction on the gut microbiota

Caloric restriction (CR) and related time-restricted diets have been popularized as means of preventing metabolic disease while improving general well-being. However, evidence as to their long-term efficacy, adverse effects, and mechanisms of activity remains incompletely understood. The gut microbiota is modulated by such dietary approaches, yet causal evidence to its possible downstream impacts on host metabolism remains elusive. Herein, we discuss the positive and adverse influences of restrictive dietary interventions on gut microbiota composition and function, and their collective impacts on host health and disease risk. We highlight known mechanisms of microbiota influences on the host, such as modulation of bioactive metabolites, while discussing challenges in achieving mechanistic dietary-microbiota insights, including interindividual variability in dietary responses as well as other methodological and conceptual challenges. In all, causally understanding the impact of CR approaches on the gut microbiota may enable to better decode their overall influences on human physiology and disease.

Fasting intervention and its clinical effects on the human host and microbiome

Experimental trials in organisms ranging from yeast to humans have shown that various forms of reducing food intake (caloric restriction) appear to increase both overall and healthy lifespan, delaying the onset of disease and slowing the progression of biomarkers of aging. The gut microbiota is considered one of the key environmental factors strongly contributing to the regulation of host health. Perturbations in the composition and activity of the gut microbiome are thought to be involved in the emergence of multiple diseases. Indeed, many studies investigating gut microbiota have been performed and have shown strong associations between specific microorganisms and metabolic diseases including overweight, obesity, and type 2 diabetes mellitus as well as specific gastrointestinal disorders, neurodegenerative diseases, and even cancer. Dietary interventions known to reduce inflammation and improve metabolic health are potentiated by prior fasting. Inversely, birth weight differential host oxidative phosphorylation response to fasting implies epigenetic control of some of its effector pathways. There is substantial evidence for the efficacy of fasting in improving insulin signaling and blood glucose control, and in reducing inflammation, conditions for which, additionally, the gut microbiota has been identified as a site of both risk and protective factors. Accordingly, human gut microbiota, both in symbiont and pathobiont roles, have been proposed to impact and mediate some health benefits of fasting and could potentially affect many of these diseases. While results from small-N studies diverge, fasting consistently enriches widely recognized anti-inflammatory gut commensals such as Faecalibacterium and other short-chain fatty acid producers, which likely mediates some of its health effects through immune system and barrier function impact.

The gut microbiota in obesity and weight management: microbes as friends or foe?

Obesity is caused by a long-term difference between energy intake and expenditure - an imbalance that is seemingly easily restored by increasing exercise and reducing caloric consumption. However, as simple as this solution appears, for many people, losing excess weight is difficult to achieve and even more difficult to maintain. The reason for this difficulty is that energy intake and expenditure, and by extension body weight, are regulated through complex hormonal, neural and metabolic mechanisms that are under the influence of many environmental factors and internal responses. Adding to this complexity, the microorganisms (microbes) that comprise the gut microbiota exert direct effects on the digestion, absorption and metabolism of food. Furthermore, the gut microbiota exerts a miscellany of protective, structural and metabolic effects both on the intestinal milieu and peripheral tissues, thus affecting body weight by modulating metabolism, appetite, bile acid metabolism, and the hormonal and immune systems. In this Review, we outline historical and recent advances in understanding how the gut microbiota is involved in regulating body weight homeostasis. We also discuss the opportunities, limitations and challenges of using gut microbiota-related approaches as a means to achieve and maintain a healthy body weight.

Gut Microbiota and Time-Restricted Feeding/Eating: A Targeted Biomarker and Approach in Precision Nutrition

Each individual has a unique gut microbiota; therefore, the genes in our microbiome outnumber the genes in our genome by about 150 to 1. Perturbation in host nutritional status influences gut microbiome composition and vice versa. The gut microbiome can help in producing vitamins, hormones, and other active metabolites that support the immune system; harvest energy from food; aid in digestion; protect against pathogens; improve gut transit and function; send signals to the brain and other organs; oscillate the circadian rhythm; and coordinate with the host metabolism through multiple cellular pathways. Gut microbiota can be influenced by host genetics, medications, diet, and lifestyle factors from preterm to aging. Aligning with precision nutrition, identifying a personalized microbiome mandates the provision of the right nutrients at the right time to the right patient. Thus, before prescribing a personalized treatment, it is crucial to monitor and count the gut flora as a focused biomarker. Many nutritional approaches that have been developed help in maintaining and restoring an optimal microbiome such as specific diet therapy, nutrition interventions, and customized eating patterns. One of these approaches is time-restricted feeding/eating (TRF/E), a type of intermittent fasting (IF) in which a subject abstains from food intake for a specific time window. Such a dietary modification might alter and restore the gut microbiome for proper alignment of cellular and molecular pathways throughout the lifespan. In this review, we have highlighted that the gut microbiota would be a targeted biomarker and TRF/E would be a targeted approach for restoring the gut-microbiome-associated molecular pathways such as hormonal signaling, the circadian system, metabolic regulators, neural responses, and immune-inflammatory pathways. Consequently, modulation of the gut microbiota through TRF/E could contribute to proper utilization and availability of the nutrients and in this way confer protection against diseases for harnessing personalized nutrition approaches to improve human health.

Intermittent fasting supports the balance of the gut microbiota composition

There is a growing body of detailed research demonstrating that intermittent fasting is essentially a cleansing activity in terms of health. Especially since its applications that exceed 16 h trigger autophagy, it continues its effect on all tissue and organ systems after the regeneration movement that starts at the cellular level. Similarly, it continues to be better understood with each passing day that the gut microbiota (GM) has many positive effects on all tissue and organ systems. Although the GM is affected by many different parameters, dietary habits are reported to be the most effective factor. Therefore, it is important to investigate the effects of different preferred fasting practices on the GM, which has numerous health benefits. Pointing out this situation, this study aims to determine the effects of 18-h intermittent fasting for 5 weeks on the shaping of GM. A 12-month-old male Wistar rat was chosen as the model organism in the study. At the end of the application, the metagenome was applied to the cecum content of the intestinal tissue collected from the sacrificed animals. Intermittent fasting practice led to an increase in alpha diversity, which expresses a significant bacterial diversity, the stabilization of Firmicutes and Bacteroidetes ratios (F/B), and the reshaping of the values with the highest prevalence in all stages of the classification, especially in the family, genus, and species care. Analysis results showed that the preferred intermittent fasting program helps balance the GM composition. This study is an important example showing the strong positive link between intermittent fasting and GM.

Alterations of gut microbiota and cytokines in elevated serum diamine oxidase disorder

The present study aimed to explore gut microbiota alterations and host cytokine responses in a population with elevated serum diamine oxidase (DAO) disorder. A total of 53 study participants were included in this study, segregated into 2 groups: subjects with high-level DAO (DAO-H, n = 22) subjects with normal DAO level (DAO-N, n = 31). We investigated the clinical and demographic parameters of study participants. The fecal bacterial communities and serum cytokines in 2 groups were assessed by 16S ribosomal RNA gene sequencing and immunoassay. High-pressure liquid chromatography was used to determine hemoglobin Alc. Flow cytometry was used to find the cytokine level in the blood serum. There is no difference in age, total cholesterol (TCHO), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), hemoglobin Alc, fasting plasma glucose (FPG) and homocysteine between the 2 groups. No significant difference were found in α-diversity between the 2 groups, however, the gut microbiota of subjects in DAO-H were characterized by marked interindividual differences, decreased abundance of Phocaeicola, Lachnospira, Bacteroides, Alistipes, Agathobacter, Lachnospira and Bactetoides and increased abundances of Mediterraneibacter, Blautia, Faecallibacterium, Agathobacter, and Parasutterella. Furthermore, the cytokines were no related to the DAO level in both groups and exhibited no significant differences between DAO-H and DAO-N. This study adds a new dimension to our understanding of the DAO and gut microbiota, and revealed that an increase in the DAO level in the intestinal mucosa could alter the gut microbiota composition, which can cause gut-related complications. Research is needed to extensively evaluate downstream pathways and provide possible protective or treatment measures pertaining to relevant disorders.

Diet and the microbiota - gut - brain-axis: a primer for clinical nutrition

PURPOSE OF REVIEW

Diet is an essential modulator of the microbiota - gut - brain communication in health and disease. Consequently, diet-induced microbiome states can impact brain health and behaviour. The integration of microbiome into clinical nutrition perspectives of brain health is sparse. This review will thus focus on emerging evidence of microbiome-targeted dietary approaches with the potential to improve brain disorders.

RECENT FINDINGS

Research in this field is evolving toward randomized controlled trials using dietary interventions with the potential to modulate pathways of the microbiota - gut - brain-axis. Although most studies included small cohorts, the beneficial effects of Mediterranean-like diets on symptoms of depression or fermented foods on the immune function of healthy individuals shed light on how this research line can grow. With a clinical nutrition lens, we highlight several methodological limitations and knowledge gaps, including the quality of dietary intake information, the design of dietary interventions, and missing behavioural outcomes.

SUMMARY

Findings in diet - microbiome - brain studies can have groundbreaking implications in clinical nutrition practice and research. Modulating brain processes through diet via the gut microbiota raises numerous possibilities. Novel dietary interventions targeting the microbiota - gut - brain-axis can offer various options to prevent and treat health problems such as mental disorders. Furthermore, knowledge in this field will improve current nutritional guidelines for disease prevention.

Characteristics of the Gut Bacterial Composition in People of Different Nationalities and Religions

High-throughput sequencing has made it possible to extensively study the human gut microbiota. The links between the human gut microbiome and ethnicity, religion, and race remain rather poorly understood. In this review, data on the relationship between gut microbiota composition and the nationality of people and their religion were generalized. The unique gut microbiome of a healthy European (including Slavic nationality) is characterized by the dominance of the phyla Firmicutes, Bacteroidota, Actinobacteria, Proteobacteria, Fusobacteria, and Verrucomicrobia. Among the African population, the typical members of the microbiota are Bacteroides and Prevotella. The gut microbiome of Asians is very diverse and rich in members of the genera Prevotella, Bacteroides Lactobacillus, Faecalibacterium, Ruminococcus, Subdoligranulum, Coprococcus, Collinsella, Megasphaera, Bifidobacterium, and Phascolarctobacterium. Among Buddhists and Muslims, the Prevotella enterotype is characteristic of the gut microbiome, while other representatives of religions, including Christians, have the Bacteroides enterotype. Most likely, the gut microbiota of people of different nationalities and religions are influenced by food preferences. The review also considers the influences of pathologies such as obesity, Crohn’s disease, cancer, diabetes, etc., on the bacterial composition of the guts of people of different nationalities.

Structural and compositional segregation of the gut microbiota in HCV and liver cirrhotic patients: A clinical pilot study

Gut microbial dysbiosis during the development of Hepatitis C virus and liver-related diseases is not well studied. Nowadays, HCV and liver cirrhosis are the major concerns that cause gut bacterial alteration, which leads to dysbiosis. For this purpose, the present study was aimed at correlating the gut bacterial community of the control group in comparison to HCV and liver cirrhotic patients. A total of 23 stool samples were collected, including control (9), liver cirrhotic (8), and HCV (6). The collected samples were subjected to 16S rRNA Illumina gene sequencing. In comparison with control, a significant gut bacterial alteration was observed in the progression of HCV and liver cirrhosis. Overall, Firmicutes were significantly abundant in the whole study. No significant difference was observed in the alpha diversity of the control and patient studies. Additionally, the beta diversity based on non-metric multidimensional scaling (NMDS) has a significant difference (p = 0.005) (ANOSIM R² = 0.14) in all groups. The discriminative results based on the LEfSe tool revealed that the HCV-infected patients had higher Enterobacteriaceae and Enterobacterial, as well as Lactobacillus and Bacilli in comparison than the liver-cirrhotic patients. These taxa were significantly different from the control group (p < 0.05). Regarding prospects, a detailed analysis of the function through metagenomics and transcriptomics is needed.

Ramadan Fasting in Health and Disease in 2021: A Narrative Review

Introduction: The literature on the health aspects of Ramadan fasting (RF) is widely spread in many journals.

Materials and Methods: This is a narrative review of data obtained from the PubMed database (National Library of Medicine, Bethesda, Maryland, United States). We used the search term “Ramadan fasting,” and relevant records were examined. The publications are narrated thematically.

Results: The publications spanned fundamental, clinical, professional, cultural, and advocacy facets. The publications crossed conventional disciplinary lines and geographical locations and appeared in journals with different access systems. The contents are presented under the themes that emerged depending on the retrieved literature. This year basic coverage included changes in physiology and nutrition during Ramadan. However, the clinical issues included a wide range of topics. These included the impact of RF on nonalcoholic fatty liver disease and adjustments needed in endocrine replacement therapy for hypothyroidism and adrenal insufficiency. Coverage also included chronic kidney disease. The impact on maternal health, fetal well-being, and long-term effects of RF exposures were addressed in several studies. Studies in cardiovascular medicine focused on blood pressure and cardiovascular risk factors. Sports medicine and athletes' well-being received somewhat prominent coverage. The impact on renal function, particularly in patients with chronic kidney disease, was investigated by a few authors. Several groups addressed the eyes' structure and function, neurological conditions, especially headache disorders, and hematological and oncological conditions. Finally, the impact of RF on several aspects of mental health and well-being was addressed by various groups.

Conclusions: Health aspects of RF received a sustained academic interest with a broad spectrum in 2021. This narration provides an overview of the year's scholarly health-related literature on various aspects of health and disease. It should help researchers and clinicians catch up quickly with the health concerns during Ramadan.

Shifts in Fecal Metabolite Profiles Associated With Ramadan Fasting Among Chinese and Pakistani Individuals

The human gut microbiota has been proposed to serve as a multifunctional organ in host metabolism, contributing effects to nutrient acquisition, immune response, and digestive health. Fasting during Ramadan may alter the composition of gut microbiota through changes in dietary behavior, which ultimately affects the contents of various metabolites in the gut. Here, we used liquid chromatography–mass spectrometry-based metabolomics to investigate the composition of fecal metabolites in Chinese and Pakistani individuals before and after Ramadan fasting. Principal component analysis showed distinct separation of metabolite profiles among ethnic groups as well as between pre- and post-fasting samples. After Ramadan fasting, the Chinese and Pakistani groups showed significant differences in their respective contents of various fecal metabolites. In particular, L-histidine, lycofawcine, and cordycepin concentrations were higher after Ramadan fasting in the Chinese group, while brucine was enriched in the Pakistani group. The KEGG analysis suggested that metabolites related to purine metabolism, 2-oxocarboxylic acid metabolism, and lysine degradation were significantly enriched in the total subject population pre-fasting vs. post-fasting comparisons. Several bacterial taxa were significantly correlated with specific metabolites unique to each ethnic group, suggesting that changes in fecal metabolite profiles related to Ramadan fasting may be influenced by associated shifts in gut microbiota. The fasting-related differences in fecal metabolite profile, together with these group-specific correlations between taxa and metabolites, support our previous findings that ethnic differences in dietary composition also drive variation in gut microbial composition and diversity. This landscape view of interconnected dietary behaviors, microbiota, and metabolites contributes to the future development of personalized, diet-based therapeutic strategies for gut-related disorders.

Effects of Ramadan and Non-ramadan Intermittent Fasting on Gut Microbiome

Background

In recent years, intermittent fasting (IF) has gained popularity in the health and wellness in the world. There are numerous types of IF, all of which involve fasting periods that last longer 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-Ramadan IF on gut microbiome.

Methods

We explored PubMed, Scopus, Web of Science, and Google Scholar according to the PRISMA criteria (Preferred Reporting Items for Systematic Reviews and Meta-Analysis). Animal and human studies were screened and reviewed separately by two researchers.

Results

Twenty-eight studies were selected after screening. Some of the studies were performed on animal models and some on humans. The results of these studies indicate a significant shift in the gut microbiota, especially an increase in the abundance of Lactobacillus and Bifidobacteria following fasting diets. The results of some studies also showed an increase in the bacterial diversity, decrease inflammation and increased production of some metabolites such as short-chain fatty acids (SCFAs) in individuals or samples under fasting diets. Moreover, Ramadan fasting, as a kind of IF, improves health parameters through positive effects on some bacterial strains such as Akkermansia muciniphila and Bacteroide. 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 on the intestinal microbiome. However, because more studies have been done on animal models, more human studies are needed to prove the results.

Differences in the Gut Microbiota Composition and Metabolites Associated With Feeding Intolerance in VLBW Infants With a Gestational Age of ≤ 30 Weeks: A Pilot Study

Objective

To explore the main variations in gut microbiota compositions, short-chain fatty acids (SCFAs) concentrations and autoinducer-2 (AI-2) levels in very-low-birth-weight (VLBW) infants with feeding intolerance (FI).

Methods

Twenty-seven VLBW infants with gestational ages of ≤30 weeks were divided into the FI group (n=14) and feeding tolerance (FT) group (n=13). The gut microbiota composition and SCFAs concentrations and AI-2 levels in feces were detected at 2 and 4 weeks after birth.

Results

There was no difference in alpha diversity between the two groups at 2 and 4 weeks after birth (P>0.05). Although the Chao index decreased (P<0.05), there was no difference in the Shannon index from 2 weeks to 4 weeks in either the FI or FT group (P>0.05). Additionally, there was no difference in beta diversity between the FI and FT groups at 2 weeks (P>0.05), but there was a significant difference in beta diversity between the two groups at 4 weeks (P<0.05) and a large difference from 2 weeks to 4 weeks in both the FI and FT groups (P<0.05). Furthermore, the composition of the microbiota at 4 weeks was significantly different from that at 2 weeks in the FI group (P<0.05). The Veillonella abundance was lower at 4 weeks in the FI group (P<0.05), but there were no differences in the compositions of the other main microbes between the two groups (P>0.05). Proteobacteria and Firmicutes were dominant in both the FI and FT groups. The concentrations of propanoic, valeric and hexanoic acids were lower in the FI group at 2 weeks, and the levels of isobutyric and valeric acids were lower at 4 weeks after birth (P<0.05). The areas under the curves (AUCs) of propanoic, butanoic and valeric acids in predicting FI were 0.878, 0.816 and 0.744, respectively. Compared with that in the FT group, the relative bioluminescence of AI-2 was lower in the FI group at 2 weeks (P<0.05), and the AUC was 0.736.

Conclusions

The main composition of the microbiota was not obviously different in infants with FI. Some SCFAs and AI-2 have moderate value in predicting FI.

Characteristics of the Intestinal Microorganisms in Middle-Aged and Elderly Patients: Effects of Smoking

Introduction: Smoking affects the occurrence and development of many diseases. We attempt to study the structure of intestinal flora in the middle-aged and elderly population as well as how smoking affects the intestinal flora. Methods: We collected population information, biochemical indicators, and patient feces from 188 middle-aged and elderly male patients, and their feces were tested for the 16S rRNA gene of intestinal flora. Results: We performed a cluster analysis on the intestinal structure of the included population and found that there was a significant difference in the number of smokers between each group (p = 0.011). Subsequently, the microbiological diversity analysis of current smokers and nonsmokers was carried out. The results indicated that there was a significant difference in species composition between the two groups (p = 0.029). Through the analysis on LEfSe differential bacteria, it was found that in current smoking patients, the abundances of the genus Bifidobacterium and the genus Coprobacillus were less, while the abundances of the genera Shigella, Paraprevotella, Burkholderia, Sutterella, Megamonas, and p-75-a5 under the family level of Erysipelotrichaceae were slightly high. We analyzed the correlation between the abundances of these eight different bacteria and clinical indicators. The results revealed the following: the abundance of the genus Bifidobacterium was negatively correlated with fasting blood glucose (r = -0.198, p = 0.006) and positively correlated with uric acid (r = 0.207, p = 0.004) and total bilirubin (r = 0.175, p = 0.017); Shigella bacteria were positively correlated with fasting blood glucose (r = 0.160, p = 0.028) and uric acid (r = 0.153, p = 0.036) levels; the genus Paraprevotella and BMI (r = -0.172, p = 0.018) are negatively correlated; the abundance of the genus Burkholderia was positively correlated with γ-glutamyltransferase (r = 0.146, p = 0.045) levels; Sutterella was correlated with fasting blood glucose (r = 0.143, p = 0.05) and creatinine level (r = -0.16, p = 0.027), which was positively correlated with fasting blood glucose and negatively correlated with creatinine. Conclusions: In middle-aged and elderly patients with cardiovascular disease, smoking can reduce the abundance of Bifidobacterium, while the abundances of some negative bacteria such as Burkholderia, Sutterella, and Megamonas increase.

The impact of dawn to sunset fasting on immune system and its clinical significance in Covid-19 pandemic

Dawn to sunset fasting, a type of intermittent fasting commonly practiced in the month of Ramadan, requires fasting from dawn to sunset without food or liquid intake. Dawn and dusk are two transition time zones of the day that play a critical role in the human circadian rhythm. Practicing dawn to sunset fasting requires the alignment of mealtimes and wake-sleep times with the human biological dawn and dusk. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impairs immune cell responses at multiple levels and leads to severe Coronavirus Disease 2019 (COVID-19). It generates high levels of pro-inflammatory cytokines and chemokines, also known as a cytokine storm, leads to mitochondrial dysfunction and generation of excessive amounts of mitochondrial reactive oxygen species, downregulates autophagy to escape detection for unchecked replication, and alters gut microbiome composition. Severe cases of COVID-19 have been associated with several comorbidities that impair immune responses (e.g., obesity, diabetes, malignancy) and blood laboratory abnormalities (e.g., elevated procalcitonin, C-reactive protein, interleukin-6 (IL-6), leukocytosis, lymphopenia). Several studies of dawn to sunset fasting showed anti-inflammatory effect by suppressing several pro-inflammatory cytokines, reducing oxidative stress, inducing a proteome response associated with increased autophagy, remodeling the gut microbiome, and improving the components of metabolic syndrome (e.g., obesity, blood glucose levels, blood pressure, lipids). In conclusion, dawn to sunset fasting has the potential to optimize the immune system function against SARS-CoV-2 during the COVID-19 pandemic as it suppresses chronic inflammation and oxidative stress, improves metabolic profile, and remodels the gut microbiome. This review presents scientific literature related to the effects of dawn to sunset fasting on the immune system. Studies are needed to assess and confirm the potential benefits of dawn to sunset fasting against SARS-CoV-2.