Research Papers

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• Published: 2020

• Source: Nature Communications

• Focus: Examining associations between gut microbiome composition and host phenotypic features, including gut symptoms, across a large population.

• Study Design: Cross-sectional study analysing gut microbiota from faecal samples of approximately 3,400 individuals using 16S rRNA sequencing, correlated with 150 host phenotypic features (e.g., gastrointestinal symptoms, lifestyle factors, and blood biomarkers).

• Findings: The study identified significant associations between gut microbiome composition and gastrointestinal symptoms such as bloating and diarrhea. Higher microbial diversity was linked to fewer symptoms, while specific microbial shifts correlated with increased symptom severity.

• Key Insight into Which Bacteria Were Imbalanced: A nonlinear relationship was observed along the *Firmicutes-to-Bacteroidetes axis, with reduced *Bacteroidetes and elevated *Firmicutes associated with increased gut symptoms. Lower diversity in SCFA-producing bacteria (e.g., *Faecalibacterium) was also noted in symptomatic individuals.​

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• Published: 2021

• Source: Frontiers in Immunology

• Focus: Investigating the role of gut microbiome dysbiosis in gastrointestinal symptoms and systemic inflammation in COVID-19 patients.

• Study Design: Observational cohort study involving 100 hospitalised COVID-19 patients, with faecal samples analysed via shotgun metagenomics compared to healthy controls. Gastrointestinal symptoms (e.g., diarrhea, nausea) were recorded.

• Findings: Patients with gut symptoms showed reduced microbial diversity and altered microbiota composition compared to asymptomatic patients and controls. Dysbiosis was linked to increased intestinal permeability and inflammation.

• Key Insight into Which Bacteria Were Imbalanced: Decreased abundance of beneficial bacteria like *Bifidobacterium and *Lactobacillus was observed, alongside an overgrowth of opportunistic pathogens such as *Enterobacteriaceae (e.g., *Escherichia coli) in symptomatic patients.​

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• Published: 2022

• Source: Gut Microbes

• Focus: Exploring the relationship between gut dysbiosis and irritable bowel syndrome (IBS) symptoms in a clinical population.

• Study Design: Case-control study with 200 IBS patients and 100 healthy controls. Gut microbiota was assessed using 16S rRNA sequencing, and symptoms (e.g., abdominal pain, bloating, diarrhea) were evaluated via standardised questionnaires.

• Findings: IBS patients exhibited significantly lower microbial diversity and distinct microbial profiles compared to controls. Symptom severity correlated with specific microbial imbalances, suggesting a role for dysbiosis in symptom generation.

• Key Insight into Which Bacteria Were Imbalanced: Reduced levels of SCFA-producing bacteria (e.g., *Faecalibacterium prausnitzii and *Roseburia) and increased *Proteobacteria (e.g., *Escherichia) were associated with worse symptoms.

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• Published: 2023

• Source: Journal of Clinical Gastroenterology

• Focus: Assessing gut microbiota alterations in patients with small intestinal bacterial overgrowth (SIBO) and associated gastrointestinal symptoms.

• Study Design: Prospective cohort study of 150 patients diagnosed with SIBO via breath testing, compared to 50 healthy controls. Faecal microbiota was analysed using shotgun metagenomics, with symptoms like bloating and abdominal discomfort tracked.

• Findings: SIBO patients showed microbial overgrowth in the small intestine and reduced diversity in the gut microbiome. Symptoms were more severe in those with pronounced dysbiosis, supporting a link between microbial imbalance and gut dysfunction.

• Key Insight into Which Bacteria Were Imbalanced: Overgrowth of facultative anaerobes like *Klebsiella and *Proteus (*Enterobacteriaceae family) was prominent, with a notable decrease in beneficial anaerobes such as Bacteroides and Clostridium species.​

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• Published: 2024

• Source: Clinical Nutrition

• Focus: Investigating the impact of gut dysbiosis on gastrointestinal symptoms in patients with inflammatory bowel disease (IBD) during remission and flare-ups.

• Study Design: Longitudinal study of 120 IBD patients (Crohn’s disease and ulcerative colitis) followed over 12 months. Faecal samples were collected during remission and flare-ups, analysed via 16S rRNA sequencing, and correlated with symptoms (e.g., diarrhea, abdominal pain).

• Findings: Dysbiosis was more pronounced during flare-ups, with reduced microbial diversity and shifts in composition linked to symptom exacerbation. Even in remission, subtle imbalances persisted, suggesting a chronic dysbiotic state.

• Key Insight into Which Bacteria Were Imbalanced: Flare-ups showed decreased *Firmicutes (e.g., *Faecalibacterium prausnitzii) and *Bacteroidetes, with increased *Proteobacteria (e.g., *Desulfovibrio).

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