The human gastrointestinal (GI) tract is colonised by an abundant and diverse microbial community that gathers more than 100 trillion microorganisms.1
Gut bacteria play the following key roles:1
• Regulators of digestion along the gastrointestinal tract; commensal bacteria play an important role in the extraction, synthesis, and absorption of many nutrients and metabolites, including bile acids, lipids, amino acids, vitamins, and short-chain fatty acids (SCFAs).
• Immune function against pathogenic bacteria colonisation by inhibiting their growth
• Prevent bacteria invasion by maintaining the intestinal epithelium integrity
Healthy gut microbiota varies according to age, ethnicity, lifestyle, and dietary habits1
Dysbiosis (imbalance) is often defined as an alteration of gut microbiota composition and a cause or a consequence of disorders
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Factors that impact microbiota balance
1. Antibiotics related alteration2
There is substantial evidence that the composition of the gut microbiota may fluctuate in response to external factors such as antibiotics. Viral and bacterial infections or allergies can be promoted by antibiotic-induced changes in the microbiota
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Microbes colonise the human gut during or shortly after birth and continue to mature throughout childhood into adulthood. The composition and activity of gut bacteria can vary according to (and possibly a result of) life events, including puberty, ovarian cycle, pregnancy and menopause. Another broad shift in gut microbe populations occurs with age and thus the gut microbiota profiles of the elderly may not be optimal
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Smoking has a significant influence on gut microbiota composition and could potentially contribute to increased risk of Crohns Disease. Exercise (or rather a lack of it) may be an important influence on any shifts in microbial populations that are associated with obesity.3 Another lifestyle factor, stress, has an impact on colonic motor activity via the gut-brain axis which can alter gut microbiota profiles. Dietary saturated fats may increase numbers of pro-inflammatory gut microbes.
Diseases associated with alterations of gut microbiota composition1
Irritable bowel syndrome (IBS)1
One of the most common gastrointestinal (GI) disorders and the bacterial role has been largely investigated. Studies suggested a weakness of the epithelial barrier as a result of a loss of microbial richness.
Inflammatory Bowel Disease (IBD)1
Refers to chronic and relapsing inflammatory conditions of the gastrointestinal tract including ulcerative colitis (UC) and Crohn’s disease (CRD). Studies suggest that gut microbial imbalances contribute to disease severity.