Other meanings of Gut microbiome
Biology
The gut microbiome is the community of microorganisms — bacteria, archaea, viruses, and fungi — living in the digestive tract, predominantly in the large intestine. It plays a crucial role in human health, influencing digestion, metabolism, immune function, and even neurological processes through the gut–brain axis. The composition and diversity of the gut microbiome are shaped by diet, age, genetics, medications, and environmental factors. Advances in metagenomic sequencing have revealed that the human gut harbours trillions of microbial cells, collectively encoding hundreds of times more genes than the human genome.
The gut microbiome is dominated by two bacterial phyla, Bacteroidetes and Firmicutes, but also contains Actinobacteria, Proteobacteria, and Verrucomicrobia1. Microbial colonisation begins at birth; vaginally delivered infants acquire similar bacteria to the maternal vaginal and faecal microbiota, whereas caesarean-born infants often harbour skin and environmental bacteria2. Breastfeeding introduces Bifidobacterium species that help metabolise human milk oligosaccharides. The microbiome matures over the first 2–3 years, reaching an adult-like complexity. Antibiotic exposure, diet, and hygiene practices can shape this developmental window, with long-term consequences for metabolic and immune health3.
The gut microbiota contributes to digestion by breaking down indigestible polysaccharides into short-chain fatty acids (SCFAs) such as butyrate, which serve as energy sources for colonocytes and have anti-inflammatory effects1. It also synthesises vitamins (e.g., biotin and folate), regulates host lipid metabolism, and stimulates the immune system. Imbalances (dysbiosis) have been linked to obesity, type 2 diabetes, inflammatory bowel disease (IBD), colorectal cancer, and even depression4. The gut–brain axis, a bidirectional communication network via the vagus nerve and microbial metabolites, is an active area of research into anxiety and neurodevelopmental disorders5.
Diet is the primary short-term modulator of the gut microbiome; high-fibre diets favour butyrate-producing bacteria, while Western diets high in fat and sugar can promote dysbiosis1 and metabolic dysfunction3. Prebiotics (non-digestible compounds that feed beneficial microbes), probiotics (live beneficial strains), and postbiotics like SCFAs are used to modify the microbiota. Antibiotics can cause dramatic reductions in diversity, sometimes with long-lasting effects, and are a major cause of Clostridioides difficile infections. Faecal microbiota transplantation (FMT), which restores a healthy microbial community, is highly effective for recurrent C. difficile infection and is being investigated for other conditions6.
Beyond bacteria, the gut harbours archaea — mainly methanogens like Methanobrevibacter smithii — that produce methane and can influence intestinal transit time7. The virome includes bacteriophages that regulate bacterial populations, and the mycobiome (fungi) interacts with the immune system. Even organisms like Helicobacter pylori, often pathogenic, have co-evolved with humans and may be commensal in some contexts. Recent studies reveal that the microbiome is involved in drug metabolism, affecting the efficacy and toxicity of medications, including digoxin and some chemotherapies8. Research also suggests that gut microbes can influence flavour perception and even affect athletic performance.
The gut microbiome is essential for health, and ongoing research continues to reveal its profound influence on human physiology and disease.
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