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The effects of time-restricted eating and Ramadan fasting on gut microbiota composition: a systematic review of human and animal studies
Abstract 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.
Mitochondrial DNA and Epigenetics: Investigating Interactions with the One‐Carbon Metabolism in Obesity
Mitochondrial DNA copy number (mtDNAcn) has been proposed for use as a surrogate biomarker of mitochondrial health, and evidence suggests that mtDNA might be methylated. Intermediates of the one‐carbon cycle (1CC), which is duplicated in the cytoplasm and mitochondria, have a major role in modulating the impact of diet on the epigenome. Moreover, epigenetic pathways and the redox system are linked by the metabolism of glutathione (GSH). In a cohort of 101 normal‐weight and 97 overweight/obese subjects, we evaluated mtDNAcn and methylation levels in both mitochondrial and nuclear areas to test the association of these marks with body weight, metabolic profile, and availability of 1CC intermediates associated with diet. Body composition was associated with 1CC intermediate availability. Reduced levels of GSH were measured in the overweight/obese group (p = 1.3∗10−5). A high BMI was associated with lower LINE‐1 (p = 0.004) and nominally lower methylenetetrahydrofolate reductase (MTHFR) gene methylation (p = 0.047). mtDNAcn was lower in overweight/obese subjects (p = 0.004) and independently correlated with MTHFR methylation levels (p = 0.005) but not to LINE‐1 methylation levels (p = 0.086). DNA methylation has been detected in the light strand but not in the heavy strand of the mtDNA. Although mtDNA methylation in the light strand did not differ between overweight/obese and normal‐weight subjects, it was nominally correlated with homocysteine levels (p = 0.035) and MTHFR methylation (p = 0.033). This evidence suggests that increased body weight might perturb mitochondrial‐nuclear homeostasis affecting the availability of nutrients acting as intermediates of the one‐carbon cycle.
β-glucuronidase activity is associated with carbohydrate metabolism but not with androgen status in overweight and obese women with polycystic ovary syndrome
Diet, Trimethylamine Metabolism, and Mitochondrial DNA: An Observational Study
ScopeMitochondrial DNA copy number (mtDNAcn) and its methylation level in the D‐loop area have been correlated with metabolic health and are suggested to vary in response to environmental stimuli, including diet. Circulating levels of trimethylamine‐n‐oxide (TMAO), which is an oxidative derivative of the trimethylamine (TMA) produced by the gut microbiome from dietary precursors, have been associated with chronic diseases and are suggested to have an impact on mitochondrial dynamics. This study is aimed to investigate the relationship between diet, TMA, TMAO, and mtDNAcn, as well as DNA methylation.Methods and resultsTwo hundred subjects with extreme (healthy and unhealthy) dietary patterns are recruited. Dietary records are collected to assess their nutrient intake and diets’ quality (Healthy Eating Index). Blood levels of TMA and TMAO, circulating levels of TMA precursors and their dietary intakes are measured. MtDNAcn, nuclear DNA methylation long interspersed nuclear element 1 (LINE‐1), and strand‐specific D‐loop methylation levels are assessed. There is no association between dietary patterns and mtDNAcn. The TMAO/TMA ratio is negatively correlated with d‐loop methylation levels but positively with mtDNAcn.ConclusionsThese findings suggest a potential association between TMA metabolism and mitochondrial dynamics (and mtDNA), indicating a new avenue for further research.
Human gut microbiota composition and its predicted functional properties in people with western and healthy dietary patterns
Abstract Purpose Some dietary habits cluster together, and for this reason it is advised to study the impact of entire dietary patterns on human health, rather than that of individual dietary habits. The main objective of this study was to evaluate differences in gut microbiota composition and their predicted functional properties between people with a healthy (HDP) and western (WDP) dietary pattern. Methods A cross-sectional, observational study was carried out on 200 participants enrolled 2017–2018 in Poznań, Poland, equally distributed into HDP and WDP groups. Diet was estimated using 3-day food records and information on stool transit times was collected. Fecal microbiota composition was assessed by 16S rRNA gene sequencing and its functional properties were predicted by the PICRUSt2 workflow. Results The α-diversity did not differ between people with WDP and HDP, but β-diversity was associated with dietary pattern. People with HDP had higher relative abundances (RA) of Firmicutes and Faecalibacterium and lower RA of Bacteroidota and Escherichia–Shigella than participants with WDP. Only a small proportion of the variance in microbiota composition (1.8%) and its functional properties (2.9%) could be explained by dietary intake (legumes, simple sugars and their sources, like fruit, soft drinks) and stool transit characteristics. Conclusion Gut microbiota composition and predicted metabolic potential is shaped by overall diet quality as well as the frequency of defecation; however, the cumulative effect of these explain only a relatively low proportion of variance.
Effect of a high-fat high-fructose diet on the composition of the intestinal microbiota and its association with metabolic and anthropometric parameters in a letrozole-induced mouse model of polycystic ovary syndrome
Ex vivo folate production by fecal bacteria does not predict human blood folate status: Associations between dietary patterns, gut microbiota, and folate metabolism
Easy Diet Screener: A quick and easy tool for determining dietary patterns associated with lipid profile and body adiposity
Abstract Background There is a lack of simple tools that could allow members of the general population to estimate their own dietary patterns and to associate them with unfavourable health outcomes. The present study aimed to develop and validate a simple self‐administered tool, called the Easy Diet Screener (EDS), that would identify healthy and unhealthy dietary patterns and evaluate their association with unfavourable blood and anthropometric parameters (i.e. values outside the recommended values). Methods In total, 259 adult people (31−50 years of age) participated in this observational study. They filled out an online version of the EDS questionnaire; those who scored highly were assigned to the healthy dietary pattern (HDP) group, whereas those with a low score were assigned to the western dietary pattern (WDP) group. The dietary records, anthropometric and biochemical parameters were evaluated in a subset of 200 participants who obtained similar score in the repeated EDS (paper version). Results People assigned to HDP on the basis of EDS had significantly better diet quality than those assigned to WDP, with values of the Healthy Eating Index being 76.9 ± 9.2 and 58.7 ± 10.5, respectively. People classed as WDP had a higher risk of too high serum low‐density lipoproteins [odds ratio (OR) = 2.65], triglycerides (OR = 3.67), body mass index (OR = 2.87) and percentage of fat tissue (OR = 3.98) than did people in the HDP. Conclusions EDS is an easy tool for quickly identifying healthy and western dietary patterns that are associated with lipid profile and body adiposity.