Realistic Targets for Prebiotic Therapy

Glenn GIBSON

Department of Food and Nutritional Sciences, The University of Reading.

Last year, ISAPP published a consensus paper on prebiotics1, including the definition of ‘a substrate that is selectively utilized by host microorganisms conferring a health benefit.’ Prebiotic safety and use at appropriate dose are key. The latter must be sufficient to generate a prebiotic effect, but not too high to induce unwanted or adverse effects. Demonstration of health benefits in well-controlled studies in the target host is required. Prebiotics therefore serve to elicit specific changes in the gut microbiota composition that increase populations of purported beneficial bacterial genera, for example, bifidobacteria. They attempt to induce beneficial changes by specifically fortifying levels of certain bacteria indigenous to the appropriate microbiome, with the gut attracting most attention at present.

Main prebiotic targets in the gut have been indigenous lactic acid producing bacteria, with interest in the development of prebiotics has been aimed at non-digestible oligosaccharides such as inulin type fructooligosaccharides and trans-galactooligosaccharides. Both have been shown to be prebiotics, through numerous volunteer trials, as evidence by their ability to positively change the gut microbiota composition after a short feeding period. They have been tested in IBS, IBD, obesity, traveller’s diarrhoea, infants, elderly persons, Metabolic Syndrome, satiety, anxiety, used to reduce infection rates and improve the bioavailability of certain minerals.

Aspects for the future may include:

  • expanding the current range of prebiotic targets e.g. fortifying genera other than bifiodobacteria, lactobacilli. Examples would be propionbacteria, roseburia, eubacteria, faecalibacteria. These may offer health aspects not currently afforded by the traditional targets
  • more widespread use in microbial ecosystems other than the gut (e.g. skin, urogenital tract, oral cavity)
  • use of waste products to generate novel prebiotics
  • use of probiotic enzymes to synthesise prebiotics
  • development of novel synbiotics

Trials that include a functional, as well as compositional, assessment of microbiota changes following prebiotic may be a useful way forward, as are further studies into clinical outcome in patients or those at risk of disorder.

 

1Nature Reviews in Gastroenterology and Hepatology 14, 491-502.