Effects of Low-Carbohydrate Diet and Exercise Training on Gut Microbiota

The effects of 6 wk of resistance training on the gut microbiome and cardiometabolic health in young adults with overweight and obesity

Obesity is a known risk factor for the development of insulin resistance and other cardiometabolic disorders. Recently, the gut microbiome has been associated with obesity and subsequent health complications. Exercise has been regularly utilized as a therapeutic intervention to treat obesity and its associated comorbidities. This study examined the effects of a 6-wk resistance training exercise program (RT) on the diversity, composition, and metabolic pathways of the gut microbiome. Sedentary young adults (age 18-35 yr) with overweight and obesity (BMI 25-45 kg/m2) were recruited to participate in this randomized controlled trial. Participants were randomized to RT (n = 16), a 6-wk resistance training program (3 days/wk), or control (CT) (n = 16), a nonexercising control. Main outcomes of the study included gut microbiome measures (taxa abundances, diversity, and predicted function) and cardiometabolic outcomes [blood pressure (BP) and glucoregulation]. Increased abundances of Roseburia, a short-chain fatty acid (SCFA) producer were observed over 6 wk (W6) with RT compared with CT (group × week, P < 0.05, q < 0.25). RT also induced marginal alterations in predicted microbial metabolic and cell motility pathways compared with CT (group × week, P < 0.05, q < 0.25). However, RT did not significantly impact overall microbial diversity. Furthermore, RT resulted in higher quantitative insulin-sensitivity check index (QUICKI) and lower diastolic BP at W6 compared with CT [baseline (BL)-adjusted P < 0.05]. RT had mixed effects on the gut microbiome. Although RT increased abundances of Roseburia and induced minor changes in microbial pathways, it is important to consider these changes in the context of the overall stability observed in the microbiome composition.NEW & NOTEWORTHY Resistance training induces mixed changes in the gut microbiome, including an increase in the abundances of the Roseburia genus and minor alterations in microbial pathways. However, it is vital to interpret these changes in light of the broader context, where we observe stability in the overall microbiome composition. This stability may be attributed to the microbiome's resilience, demonstrating its capacity to withstand short-term physiological stressors.

A systematic review on the effects of exercise on gut microbial diversity, taxonomic composition, and microbial metabolites: identifying research gaps and future directions

The gut microbiome, hosting a diverse microbial community, plays a pivotal role in metabolism, immunity, and digestion. While the potential of exercise to influence this microbiome has been increasingly recognized, findings remain incongruous. This systematic review examined the effects of exercise on the gut microbiome of human and animal models. Databases (i.e., PubMed, Cochrane Library, Scopus, and Web of Science) were searched up to June 2022. Thirty-two exercise studies, i.e., 19 human studies, and 13 animal studies with a minimum of two groups that discussed microbiome outcomes, such as diversity, taxonomic composition, or microbial metabolites, over the intervention period, were included in the systematic review (PROSPERO registration numbers for human review: CRD42023394223). Results indicated that over 50% of studies found no significant exercise effect on human microbial diversity. When evident, exercise often augmented the Shannon index, reflecting enhanced microbial richness and evenness, irrespective of disease status. Changes in beta-diversity metrics were also documented with exercise but without clear directionality. A larger percentage of animal studies demonstrated shifts in diversity compared to human studies, but without any distinct patterns, mainly due to the varied effects of predominantly aerobic exercise on diversity metrics. In terms of taxonomic composition, in humans, exercise usually led to a decrease in the Firmicutes/Bacteroidetes ratio, and consistent increases with Bacteroides and Roseburia genera. In animal models, Coprococcus, another short chain fatty acid (SCFA) producer, consistently rose with exercise. Generally, SCFA producers were found to increase with exercise in animal models. With regard to metabolites, SCFAs emerged as the most frequently measured metabolite. However, due to limited human and animal studies examining exercise effects on microbial-produced metabolites, including SCFAs, clear patterns did not emerge. The overall risk of bias was deemed neutral. In conclusion, this comprehensive systematic review underscores that exercise can potentially impact the gut microbiome with indications of changes in taxonomic composition. The significant variability in study designs and intervention protocols demands more standardized methodologies and robust statistical models. A nuanced understanding of the exercise-microbiome relationship could guide individualized exercise programs to optimize health. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=394223, identifier CRD42023394223.

The Influence of Ketogenic Diet on Gut Microbiota: Potential Benefits, Risks and Indications

The ketogenic diet (KD) restricts carbohydrate consumption, leading to an increase in ketone bodies, such as acetoacetate, β-hydroxybutyrate, and acetone, which are utilized as energy substrates. This dietary approach impacts several biochemical processes, resulting in improved clinical management of various disorders, particularly in childhood. However, the exact mechanisms underlying the efficacy of KD remain unclear. Interestingly, KD may also impact the gut microbiota, which plays a pivotal role in metabolism, nutrition, and the development of the immune and nervous systems. KD has gained popularity for its potential benefits in weight loss, blood sugar control, and certain neurological conditions. This narrative review sums up KD-related studies published over 30 years. While short-term studies have provided valuable insights into the effects of KD on the gut microbiota, persistent uncertainties surround its long-term efficacy and potential for inducing dysbiosis. The significant influence of KD on epigenetic mechanisms, intracellular pathways, and gut microbial composition underscores its potential as a therapeutic choice. However, a judicious consideration of the potential risks associated with the strict adherence to a low-carbohydrate, high-fat, and high-protein regimen over prolonged periods is imperative. As KDs gain popularity among the adolescent and young adult demographic for weight management, it becomes imperative to undertake additional research to comprehensively assess their impact on nutritional status and gut microbiota, ensuring a holistic and sustainable approach to medical nutrition.

Understanding the impact of spinal cord injury on the microbiota of healthy skin and pressure injuries

Pressure injuries (PI) are a common issue among individuals with spinal cord injury (SCI), especially in the sitting areas of the body. Considering the risk of infections occurring to PI during the wound healing process, the skin microbiome is likely to be a source of bacteria. We investigated the relationship between skin and PI microbiomes, and assessed any correlation with clinically relevant outcomes related to PI. Samples were isolated from SCI patients undergoing reconstructive surgery of PI, severity grades III and IV. DNA samples from skin and PI were analysed using 16S rRNA gene sequencing. Our results showed disparities in microbiome composition between skin and PI. The skin had lower diversity, while PI showed increased bacterial homogeneity as the severity grade progressed. The skin bacterial composition varied based on its location, influenced by Cutibacterium. Compositional differences were identified between PI grades III and IV, with clusters of bacteria colonizing PI, characterized by Pseudomonas, Proteus and Peptoniphilus. The skin and PI microbiomes were not affected by the level of the SCI. Our study highlights the differences in the microbiome of skin and PI in SCI patients. These findings could be used to target specific bacteria for PI treatment in clinical practice.

Fecal Microbiota Composition as a Metagenomic Biomarker of Dietary Intake

Gut microbiota encompasses the set of microorganisms that colonize the gastrointestinal tract with mutual relationships that are key for host homeostasis. Increasing evidence supports cross intercommunication between the intestinal microbiome and the eubiosis-dysbiosis binomial, indicating a networking role of gut bacteria as potential metabolic health surrogate markers. The abundance and diversity of the fecal microbial community are already recognized to be associated with several disorders, such as obesity, cardiometabolic events, gastrointestinal alterations, and mental diseases, which suggests that intestinal microbes may be a valuable tool as causal or as consequence biomarkers. In this context, the fecal microbiota could also be used as an adequate and informative proxy of the nutritional composition of the food intake and about the adherence to dietary patterns, such as the Mediterranean or Western diets, by displaying specific fecal microbiome signatures. The aim of this review was to discuss the potential use of gut microbial composition as a putative biomarker of food intake and to screen the sensitivity value of fecal microbiota in the evaluation of dietary interventions as a reliable and precise alternative to subjective questionnaires.

Characterization of Gut Microbiota Composition in Type 2 Diabetes Patients: A Population-Based Study

(1) Background: A clinical laboratory index to assess gut dysbiosis is the F/B ratio < 0.8. In fact, an elevated proportion of Firmicutes and a reduced population of Bacteroides in diabetes type 2 (T2D) subjects has been observed. This study aimed to detail the dysbiosis status in the Italian population, focusing on some pathogenic spectra (T2D) or metabolic disorders. (2) Material and methods: A quantity of 334 fecal samples was analyzed in order to perform genetic testing and sequencing. (3) Results: A trend in over imbalance was observed in the percentage of Proteobacteria (median value: 6.75%; interquartile range (IQR): 3.57−17.29%). A statistically significant association (χ2p = 0.033) was observed between type of dysbiosis and T2D, corresponding to an Odds Ratio (OR) of 1.86. It was noted that females with cystitis/candidiasis are significantly prevalent in T2D patients (p < 0.01; OR: 3.59; 95% CI: 1.43−8.99). Although, in non-diabetic males, a sugar craving is significantly associated with the rate of dysbiosis in non-diabetic males (p < 0.05; OR 1.07; 95% CI 1.00−1.16). (4) Conclusion: In T2D patients, the Bacteroidetes/Firmicutes ratio was biased in favor of Proteobacteria, to be expected due to the nutritional habits of the patients. Thus, T2D females had altered gut permeability favoring the development of infections in the vaginal tract.

Running-Induced Metabolic and Physiological Responses Using New Zealand Blackcurrant Extract in a Male Ultra-Endurance Runner: A Case Study

Physical training for ultra-endurance running provides physiological adaptations for exercise-induced substrate oxidation. We examined the effects of New Zealand blackcurrant (NZBC) extract on running-induced metabolic and physiological responses in a male amateur ultra-endurance runner (age: 40 years, body mass: 65.9 kg, BMI: 23.1 kg·m−2, body fat: 14.7%, V˙O2max: 55.3 mL·kg−1·min−1, resting heart rate: 45 beats·min−1, running history: 6 years, marathons: 20, ultra-marathons: 28, weekly training distance: ~80 km, weekly running time: ~9 h). Indirect calorimetry was used and heart rate recorded at 15 min intervals during 120 min of treadmill running (speed: 10.5 km·h−1, 58% V˙O2max) in an environmental chamber (temperature: ~26 °C, relative humidity: ~70%) at baseline and following 7 days intake of NZBC extract (210 mg of anthocyanins·day−1) with constant monitoring of core temperature. The male runner had unlimited access to water and consumed a 100-kcal energy gel at 40- and 80 min during the 120 min run. There were no differences (mean of 8, 15 min measurements) for minute ventilation, oxygen uptake, carbon dioxide production and core temperature. With NZBC extract, the respiratory exchange ratio was 0.02 units lower, carbohydrate oxidation was 11% lower and fat oxidation was 23% higher (control: 0.39 ± 0.08, NZBC extract: 0.48 ± 0.12 g·min−1, p < 0.01). Intake of the energy gel did not abolish the enhanced fat oxidation by NZBC extract. Seven days’ intake of New Zealand blackcurrant extract altered exercise-induced substrate oxidation in a male amateur ultra-endurance runner covering a half-marathon distance in 2 h. More studies are required to address whether intake of New Zealand blackcurrant extract provides a nutritional ergogenic effect for ultra-endurance athletes to enhance exercise performance.

Combined Physical Exercise and Diet: Regulation of Gut Microbiota to Prevent and Treat of Metabolic Disease: A Review

BACKGROUND

Unhealthy diet and sedentary lifestyle have contributed to the rising incidence of metabolic diseases, which is also accompanied by the shifts of gut microbiota architecture. The gut microbiota is a complicated and volatile ecosystem and can be regulated by diet and physical exercise. Extensive research suggests that diet alongside physical exercise interventions exert beneficial effects on metabolic diseases by regulating gut microbiota, involving in the changes of the energy metabolism, immune regulation, and the microbial-derived metabolites.

OBJECTIVE

In this review, we present the latest evidence in the modulating role of diet and physical exercise in the gut microbiota and its relevance to metabolic diseases. We also summarize the research from animal and human studies on improving metabolic diseases through diet-plus-exercise interventions, and new targeted therapies that might provide a better understanding of the potential mechanisms.

METHODS

A systematic and comprehensive literature search was performed in PubMed/Medline and Web of Science in October 2022. The key terms used in the searches included "combined physical exercise and diet", "physical exercise, diet and gut microbiota", "physical exercise, diet and metabolic diseases" and "physical exercise, diet, gut microbiota and metabolic diseases".

CONCLUSIONS

Combined physical exercise and diet offer a more efficient approach for preventing metabolic diseases via the modification of gut microbiota, abating the burden related to longevity.

Effect of Intensity and Duration of Exercise on Gut Microbiota in Humans: A Systematic Review

(1) Background: The gut microbiota might play a part in affecting athletic performance and is of considerable importance to athletes. The aim of this study was to search the recent knowledge of the protagonist played by high-intensity and high-duration aerobic exercise on gut microbiota composition in athletes and how these effects could provide disadvantages in sports performance. (2) Methods: This systematic review follows the PRISMA guidelines. An exhaustive bibliographic search in Web of Science, PubMed, and Scopus was conducted considering the articles published in the last 5 years. The selected articles were categorized according to the type of study. The risk of bias was assessed using the Joanna Briggs Institute's Critical Appraisal Tool for Systematic Reviews. (3) Results: Thirteen studies had negative effects of aerobic exercise on intestinal microbiota such as an upsurge in I-FABP, intestinal distress, and changes in the gut microbiota, such as an increase in Prevotella, intestinal permeability and zonulin. In contrast, seven studies observed positive effects of endurance exercise, including an increase in the level of bacteria such as increased microbial diversity and increased intestinal metabolites. (4) Conclusions: A large part of the studies found reported adverse effects on the intestinal microbiota when performing endurance exercises. In studies carried out on athletes, more negative effects on the microbiota were found than in those carried out on non-athletic subjects.