TableĀ 2

Mechanisms of action of probiotics (based on ref. 1)

Mechanism*Examples
Widespread (thought to be common among probiotic genera)
  • Colonisation resistance

  • Acid and short-chain fatty acid production

  • Regulation of intestinal transit

  • Normalisation of perturbed microbiota

  • Increased turnover of enterocytes

  • Competitive exclusion of pathogens

Frequent (common among probiotic strains)
  • Vitamin synthesis

  • Direct antagonism

  • Gut barrier reinforcement

  • Bile salt metabolism

  • Enzyme activity

  • Neutralisation of carcinogens

Rare (strain-specific)
  • Immunological effects

  • Production of specific bioactives

  • Endocrinological effects

  • Neurological effects

  • *It is likely that several mechanisms operate simultaneously; however, it is considered unlikely that a given individual probiotic might exert all three mechanisms.