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A Low Glycemic Index Mediterranean Diet Combined with Aerobic Physical Activity Rearranges the Gut Microbiota Signature in NAFLD Patients.
Calabrese, FM, Disciglio, V, Franco, I, Sorino, P, Bonfiglio, C, Bianco, A, Campanella, A, Lippolis, T, Pesole, PL, Polignano, M, et al
Nutrients. 2022;14(9)
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Non-alcoholic fatty liver disease (NAFLD) is the most common metabolic-associated fatty liver disease. The gut microbiota and its metabolites were demonstrated to play a role in the pathophysiology of NAFLD through the gut–liver axis. The aim of this study was to investigate how different lifestyle interventions, including diet and physical activity, can impact the gut microbiota composition in NAFLD patients after 45 and 90 days of treatment. This study was a randomised controlled trial based on lifestyle interventions. Participants were randomly allocated to one of the six groups. Results showed that nutritional therapies based on dietary interventions contributed to reduce the dysbiosis characterising NAFLD patients, increasing the resilience of microbial communities inhabiting the gut. Furthermore, the adoption of an aerobic exercise programme, in combination with the Mediterranean diet, was able to further ameliorate specific ratios of microbes. Authors conclude that the findings of their study highlight the contribution resulting from the synergistic effect of lifestyle interventions (diet and/or physical activity programs) on the composition of the gut microbiota in NAFLD patients.
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, and its prevalence worldwide is increasing. Several studies support the pathophysiological role of the gut-liver axis, where specific signal pathways are finely tuned by intestinal microbiota both in the onset and progression of NAFLD. In the present study, we investigate the impact of different lifestyle interventions on the gut microbiota composition in 109 NAFLD patients randomly allocated to six lifestyle intervention groups: Low Glycemic Index Mediterranean Diet (LGIMD), aerobic activity program (ATFIS_1), combined activity program (ATFIS_2), LGIMD plus ATFIS_1 or ATFIS2 and Control Diet based on CREA-AN (INRAN). The relative abundances of microbial taxa at all taxonomic levels were explored in all the intervention groups and used to cluster samples based on a statistical approach, relying both on the discriminant analysis of principal components (DAPCs) and on a linear regression model. Our analyses reveal important differences when physical activity and the Mediterranean diet are merged as treatment and allow us to identify the most statistically significant taxa linked with liver protection. These findings agree with the decreased 'controlled attenuation parameter' (CAP) detected in the LGIMD-ATFIS_1 group, measured using FibroScan®. In conclusion, our study demonstrates the synergistic effect of lifestyle interventions (diet and/or physical activity programs) on the gut microbiota composition in NAFLD patients.
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Dietary supplementation with inulin-propionate ester or inulin improves insulin sensitivity in adults with overweight and obesity with distinct effects on the gut microbiota, plasma metabolome and systemic inflammatory responses: a randomised cross-over trial.
Chambers, ES, Byrne, CS, Morrison, DJ, Murphy, KG, Preston, T, Tedford, C, Garcia-Perez, I, Fountana, S, Serrano-Contreras, JI, Holmes, E, et al
Gut. 2019;68(8):1430-1438
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Literature shows that higher intakes of dietary fibre are associated with a reduced risk of type 2 diabetes. The main aim of this study was to elucidate the underlying mechanisms behind improvements in glucose homeostasis following long-term delivery of propionate (a short-chain fatty acid produced by human gut microbiota in response to dietary fibre) to the human colon. The study is a randomised, double-blind, placebo-controlled cross over trial. Fourteen participants randomly received 20 g/day of a low-fermentable fibre control, a high-fermentable fibre control and inulin-propionate ester (IPE) for 42 days each. Results indicate that stool concentrations of short-chain fatty acids were not different following the three supplementation periods. Furthermore, dietary supplementation with 20 g/day IPE promoted no superior impacts on measures of glucose homeostasis compared with inulin (high-fermentable fibre), yet both IPE and inulin improved insulin resistance relative to cellulose (low-fermentable fibre). Authors conclude that manipulating the colonic fermentation profile of a dietary fibre in favour of propionate promotes selective effects on the mechanisms that contribute to metabolic dysregulation.
Abstract
OBJECTIVE To investigate the underlying mechanisms behind changes in glucose homeostasis with delivery of propionate to the human colon by comprehensive and coordinated analysis of gut bacterial composition, plasma metabolome and immune responses. DESIGN Twelve non-diabetic adults with overweight and obesity received 20 g/day of inulin-propionate ester (IPE), designed to selectively deliver propionate to the colon, a high-fermentable fibre control (inulin) and a low-fermentable fibre control (cellulose) in a randomised, double-blind, placebo-controlled, cross-over design. Outcome measurements of metabolic responses, inflammatory markers and gut bacterial composition were analysed at the end of each 42-day supplementation period. RESULTS Both IPE and inulin supplementation improved insulin resistance compared with cellulose supplementation, measured by homeostatic model assessment 2 (mean±SEM 1.23±0.17 IPE vs 1.59±0.17 cellulose, p=0.001; 1.17±0.15 inulin vs 1.59±0.17 cellulose, p=0.009), with no differences between IPE and inulin (p=0.272). Fasting insulin was only associated positively with plasma tyrosine and negatively with plasma glycine following inulin supplementation. IPE supplementation decreased proinflammatory interleukin-8 levels compared with cellulose, while inulin had no impact on the systemic inflammatory markers studied. Inulin promoted changes in gut bacterial populations at the class level (increased Actinobacteria and decreased Clostridia) and order level (decreased Clostridiales) compared with cellulose, with small differences at the species level observed between IPE and cellulose. CONCLUSION These data demonstrate a distinctive physiological impact of raising colonic propionate delivery in humans, as improvements in insulin sensitivity promoted by IPE and inulin were accompanied with different effects on the plasma metabolome, gut bacterial populations and markers of systemic inflammation.