The Vital Role of the Gut Microbiota

The gut microbiota and human host have a symbiotic relationship that helps promote health and prevent disease.4,7 Gut microbiota are key regulators of physiologic, metabolic, and immune-related processes that are required in maintaining homeostasis.3,15,16

Compelling evidence also suggests that gut microbiota can influence the activity of other organ systems, including the CNS.3,17

  • Metabolism
  • First Line of Defense
  • Gut-Brain Connection


  • Intestinal bacteria are involved in3,15-17:
    • Synthesis of essential vitamins and amino acids
    • Absorption of nutrients
    • Digestion of otherwise indigestible carbohydrates, dietary fibers, proteins, and complex polysaccharides
  • Gut microbiota also produce short-chain fatty acids, such as acetic, propionic, and butyric acids, which serve as an energy source to the host intestinal epithelium and stimulate secretion of intestinal peptides involved in glucose metabolism and food intake3,15-17

First Line of Defense

  • Gut microbiota are the body's first line of defense against GI pathogens and toxins.3,14 A healthy gut microbiome works with the immune system to protect the host by3,18:
    • Producing antimicrobial compounds (eg, bacteriocin)
    • Outcompeting pathogens for nutrients
    • Selectively preventing bacteria from adhering to the intestinal wall
  • Gut microbiota also influence GI immune system development and help regulate immune response and inflammation in the GI tract3,18

Gut-Brain Connection

  • A bidirectional exchange between gut microbiota and the CNS has been observed in animal studies.19,20 These systems communicate through the vagus nerve, the hypothalamic pituitary adrenal axis, and the production of neurotransmitters and their precursors3
  • Although the bidirectional communication between the CNS and gut microbiota has yet to be validated in humans, ongoing research has the potential to influence clinical specialties beyond gastroenterology19-21
CNS = central nervous system
GI = gastrointestinal

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