Intestinal microbiota, diet and health

Br J Nutr. 2014 Feb;111(3):387-402. doi: 10.1017/S0007114513002560. Epub 2013 Aug 12.


The human intestine is colonised by 10¹³ to 10¹⁴ micro-organisms, the vast majority of which belong to the phyla Firmicutes and Bacteroidetes. Although highly stable over time, the composition and activities of the microbiota may be influenced by a number of factors including age, diet and antibiotic treatment. Although perturbations in the composition or functions of the microbiota are linked to inflammatory and metabolic disorders (e.g. inflammatory bowel diseases, irritable bowel syndrome and obesity), it is unclear at this point whether these changes are a symptom of the disease or a contributing factor. A better knowledge of the mechanisms through which changes in microbiota composition (dysbiosis) promote disease states is needed to improve our understanding of the causal relationship between the gut microbiota and disease. While evidence of the preventive and therapeutic effects of probiotic strains on diarrhoeal illness and other intestinal conditions is promising, the exact mechanisms of the beneficial effects are not fully understood. Recent studies have raised the question of whether non-viable probiotic strains can confer health benefits on the host by influencing the immune system. As the potential health effect of these non-viable bacteria depends on whether the mechanism of this effect is dependent on viability, future research needs to consider each probiotic strain on a case-by-case basis. The present review provides a comprehensive, updated overview of the human gut microbiota, the factors influencing its composition and the role of probiotics as a therapeutic modality in the treatment and prevention of diseases and/or restoration of human health.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Aging*
  • Animals
  • Anti-Bacterial Agents / adverse effects
  • Diet* / adverse effects
  • Dietary Supplements
  • Gram-Negative Bacteria / drug effects
  • Gram-Negative Bacteria / growth & development
  • Gram-Negative Bacteria / immunology
  • Gram-Positive Bacteria / drug effects
  • Gram-Positive Bacteria / growth & development
  • Gram-Positive Bacteria / immunology
  • Health Status*
  • Humans
  • Inflammatory Bowel Diseases / diet therapy
  • Inflammatory Bowel Diseases / immunology
  • Inflammatory Bowel Diseases / microbiology
  • Inflammatory Bowel Diseases / prevention & control
  • Intestinal Mucosa / drug effects
  • Intestinal Mucosa / growth & development
  • Intestinal Mucosa / immunology
  • Intestinal Mucosa / microbiology
  • Intestines / drug effects
  • Intestines / growth & development
  • Intestines / immunology
  • Intestines / microbiology*
  • Irritable Bowel Syndrome / diet therapy
  • Irritable Bowel Syndrome / immunology
  • Irritable Bowel Syndrome / microbiology
  • Irritable Bowel Syndrome / prevention & control
  • Microbial Viability / drug effects
  • Models, Biological*
  • Probiotics / therapeutic use*


  • Anti-Bacterial Agents