Research Papers

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• Published: July 2021

• Source: ScienceDirect (Exploring the Influence of Gut Microbiome on Energy Metabolism in Humans)

• Focus: Investigate how gut microbiome composition influences energy metabolism, including energy harvest and expenditure, in humans.

• Study Design: A narrative review synthesising recent human studies, including intervention trials (e.g., caloric restriction, overfeeding) and observational data. Methods involved microbiota sequencing, energy expenditure via doubly labeled water, and fecal energy loss measurements.

• Findings: Caloric restriction increased microbial diversity and taxa like Verrucomicrobia (e.g., Akkermansia muciniphila), reducing energy harvest, while overfeeding enriched Lachnospiraceae, enhancing energy extraction. No consistent microbial signature universally tied to energy expenditure was found across studies. Probiotic interventions showed variable effects.

• Key Insights in Terms of Imbalanced Bacteria: An imbalance with lower diversity and reduced Akkermansia was linked to higher energy harvest, potentially increasing energy levels for storage or use. A shift toward diverse, mucin-degrading bacteria under restriction suggested lower energy availability, reflecting microbial adaptation to limited substrates.

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• Published: January 25, 2022

• Source: Gut Microbes (PMC)

• Focus: Assess the gut microbiome’s role in energy metabolism and fatigue in patients with chronic fatigue syndrome (CFS).

• Study Design: A cross-sectional study with 50 CFS patients and 50 age- and sex-matched healthy controls. Fecal microbiota was analyzed via 16S rRNA sequencing, and energy metabolism markers (e.g., SCFAs, lactate) were measured alongside self-reported fatigue scores.

• Findings: CFS patients exhibited reduced microbial diversity, lower Bacteroidetes, and higher Firmicutes compared to controls. Fecal SCFA levels (e.g., butyrate) were reduced, correlating with lower energy availability and higher fatigue. Specific taxa like Faecalibacterium prausnitzii, a butyrate producer, were depleted in CFS patients.

• Key Insights in Terms of Imbalanced Bacteria: An imbalance favoring Firmicutes over Bacteroidetes and reduced butyrate-producing bacteria (e.g., Faecalibacterium) was associated with lower energy availability, contributing to fatigue. This suggests microbial dysbiosis may impair energy metabolism in low-energy states.

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• Published: March 15, 2020

• Source: The American Journal of Clinical Nutrition

• Focus: Explore the effects of a high-fiber diet on gut microbiota and energy harvest in overweight adults.

• Study Design: A randomized controlled trial with 60 overweight adults assigned to a high-fiber diet (30 g/day) or a control diet for 12 weeks. Gut microbiota was sequenced, and energy harvest was assessed via fecal energy content (bomb calorimetry) and body weight changes.

• Findings: The high-fiber group showed increased Bacteroidetes and decreased Firmicutes, alongside a 90 kcal/day increase in fecal energy loss compared to controls. Weight loss was modest but significant, with no change in reported energy intake or expenditure, pointing to reduced energy harvest.

• Key Insights in Terms of Imbalanced Bacteria: An imbalance with higher Firmicutes on the control diet enhanced energy harvest, potentially increasing energy availability. The shift toward Bacteroidetes on the high-fiber diet reduced energy extraction, suggesting a microbial role in lowering available energy levels.

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• Published: October 12, 2023

• Source: Frontiers in Microbiology

• Focus: Investigate the gut microbiome’s influence on energy metabolism in athletes vs. sedentary individuals.

• Study Design: A comparative study with 30 endurance athletes and 30 sedentary controls. Fecal microbiota was analyzed via metagenomic sequencing, and energy metabolism was assessed through resting metabolic rate (RMR) and fecal SCFA concentrations.

• Findings: Athletes had higher microbial diversity and elevated levels of Prevotella and Akkermansia, with increased fecal SCFAs (e.g., acetate, propionate) compared to sedentary controls. RMR was slightly higher in athletes, but energy harvest differences were minimal, suggesting microbial metabolites supported energy utilization rather than harvest.

• Key Insights in Terms of Imbalanced Bacteria: An imbalance with lower diversity and reduced Prevotella/Akkermansia in sedentary individuals was linked to lower SCFA production, potentially limiting energy availability for physical activity. A balanced, diverse microbiome in athletes supported higher energy levels via metabolic efficiency.

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*The Comprehensive Gut Analysis tests for high levels of β-glucuronidase an overgrowth of the microbes mentioned in these studies. 

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