Probiotics vs. Prebiotics

There are some significant differences between probiotic and prebiotic supplements in terms of what they are, how they work and what they do in the digestive system.


What are prebiotics?

A prebiotic is “a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confer benefits on the host wellbeing and health”. 1

Prebiotics occur naturally in foods like asparagus, onion, banana and chicory, and in human breast milk. They are also enzymatically produced.

In order to be classed as a prebiotic, the ingredient must fulfil the following three criteria:

  1. Resists gastric acidity, hydrolysis by mammalian enzymes and gastrointestinal absorption
  2. Is fermented by the intestinal microflora
  3. Stimulates selectively the growth and/or activity of the intestinal bacteria associated with health and wellbeing.

The final criterion must be confirmed in-vivo via clinical trials using validated methodologies to produce sound scientific data2.

The scientific evidence for the use of prebiotics is found mainly in the areas of enhanced gut microflora3,4 and immune protection5,6,7,8.

Types of prebiotics

Prebiotics that currently fulfil all three class criteria are: 

  • Fructo-oligosaccharides (FOS)
  • Galacto-oligosaccharides (GOS)
  • Lactulose

Prebiotics are either 1st generation or 2nd generation. FOS, GOS (except B-GOS) and lactulose prebiotics are classed as 1st generation. There is only one 2nd generation prebiotic; this is referred to as a B-GOS and is commercially available under the brand name Bimuno®.

1st generation prebiotics are selective at the genus level. In other words they are fermented at the family group level (e.g. by bifidobacteria or lactobacillus level) and produce a prebiotic effect – increasing the number and activity of the beneficial bacteria – or a bifidogenic effect – increasing the number and strength of the bifidobacteria.

2nd generation prebiotics are tailor made to offer selectivity at species level (e.g. by Bifidobacterium bifidum) and also offer added functionality i.e. anti-adhesive or anti-pathogenic properties.

The development of 2nd generation prebiotics resulted from research into GOS structures that could potentially offer protection of the gut from infection and inflammation. It had previously been suggested that such novel GOS structures could simulate receptor sites causing a ‘decoy’ for the pathogen (E.coli and Salmonella species) not to colonise the gut wall9.

What are probiotics?

Probiotics are defined as ‘live microorganisms’, which – when administered in adequate quantities – confer a health benefit to the host’10.

They are mainly lactobacilli and bifidobacteria. Certain bifidobacteria and lactobacilli species and strains have been proven to have a beneficial effect on the host’s health and contribute to the prevention of certain diseases11, 12.

Probiotic supplements & foods

Probiotic supplements and foods are products containing live bacteria that have a beneficial effect on gut microflora and on the host’s health13.

Once ingested, these live bacteria need to survive the passage through the upper gastrointestinal tract, the acidity of the stomach, secretions of the small intestine and then compete with existing bacteria in the gut for colonisation sites.

Two critical factors in the development of fermented milk products and other foods containing probiotic bacteria, are the survival of the bacteria, both in the food or supplement and after digestion. It is unclear, however, what proportion of the live bacteria available in probiotic foods and supplements, such as tablets, capsules or dairy foods, actually reach and colonise the large intestine14.

One approach to overcome these problems was to introduce non-digestible food ingredients that target the beneficial bacteria already resident in the large intestine. These ingredients are known as prebiotics.

Key points

  • Prebiotics are: Selective fermented ingredients that allow specific changes, both in the composition and/or activity in the gastrointestinal microflora, that confer benefits on the host wellbeing and health
  • Prebiotics are food for the gut’s resident beneficial bacteria.
  • Prebiotics are not live bacteria.
  • They selectively stimulate the growth and/or activity of particular beneficial bacteria in the colon, improving host health.
  • Prebiotics are mainly oligosaccharides that have been proven in clinical trials to have a prebiotic effect, i.e. FOS and GOS. Lactulose is also considered a prebiotic.
  • 1st generation prebiotics are naturally derived and offer selectivity at genus level.
  • 2nd generation prebiotics, Bimuno® , are tailor made to offer selectivity at species level and also offer added functionality beyond selective fermentation by probiotic bacteria i.e. anti-adhesive properties.
  • Probiotics are: Live microorganism which when administered in adequate amounts confer a health benefit to the host” (FAO/WHO,2002).
  • Mainly consist of strains of Bifidobacterium spp and/or Lactobacillus spp.
  • On arrival in the colon, probiotic bacteria from foods & supplements need to compete against resident microflora for colonisation sites.
  • Because the composition of the colonic microflora varies greatly between people, the efficacy of a probiotic supplement very much depends on the host.
  • Probiotic properties are strain specific.


  1. Gibson GR et al. J Nutr.1995;125:1401-12.
  2. Diplock AT et al. Br J Nutr. 1991;81:Suppl 1:s1-s28.
  3. Wang X et al. J Appl Bacteriol. 1993;75:373-380.
  4. Langlands SJ et al. Gut 2004;53(11):1610-1616.
  5. Yoshita M et al. Bifidobacteria Microflora 1991;10:11-17.
  6. Veereman G et al. J Nutr(2007) Nov;137(Suppl 11):2585S-2589S.
  7. Saavedra JM et al. Br J Nutr(2002);87 (Suppl 2):S241-S246.
  8. Karakan T et al. World J Gastroenterol (2007);19:2733-2737.
  9. Gibson GR et al. Br J Nutr (2005);Apr;93 (Suppl 1):S31-S34.
  10. WHO 2002.
  11. Marteau PR. Clin Rev Allergy Immunol 2002;22:255-73.
  12. Ouwehand AC et al. Antonie van Leeuwenhoek 2002;82:279-89.
  13. Gut Health. Flair-Flow 4 synthesis report. Finn holm. FoodGroup Denmark. Nov 2001.
  14. Gibson GR et al.

Back to Healthcare Professionals


This section is an information and educational resource for healthcare professionals, scientists, researchers and journalists. It is not intended for consumers. If you wish to purchase Bimuno please click here

Back to the top