Caister Academic Press

What are Probiotics?

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An introduction to Probiotics.


Probiotics are products aimed at delivering living bacterial cells to the gut ecosystem of humans and other animals. Prebiotics are non-digestible carbohydrates delivered in food to the large intestine to provide fermentable substrates in order to promote the growth of specific bacteria. Molecular technology has been used in recent years to study the gut microbiota and the information gained has been useful for the evaluation and selection of probiotic bacteria. (Reference: Probiotics and Prebiotics: Scientific Aspects ISBN: 978-1-904455-01-1)

In recent years much interest has been shown in the use of bacteria as probiotics and their potential for disease prevention in humans and animals. Probiotics are living bacteria or other microorganisms which are beneficial to health when consumed. Probiotics can be beneficial for gastrointestinal infections, irritable bowel syndrome and inflammatory bowel disease. Bacteria such as Lactobacillus and Bifidobacterium are probiotics that have been shown to have anti-inflammatory and anti-cancer activities. Recent scientific research shows that probiotics can inhibit liver, colon, bladder and mammary tumors in animals. (Reference: Lactobacillus Molecular Biology: From Genomics to Probiotics ISBN: 978-1-904455-41-7)

Saccharomyces boulardii, a species of yeast, has been described as a biotherapeutic agent and several clinical trials have shown its beneficial effects in the prevention and the treatment of intestinal infections and in the maintenance of inflammatory bowel disease. All these diseases are characterized by acute diarrhoea. Administration of the yeast in combination or not with an antibiotherapy has shown to decrease significantly the duration and the frequency of diarrhoea. Curr. Issues Mol. Biol. (2009) 11: 47-58

The use of probiotics has been evaluated in cases of antibiotic-associated diarrhoea, travellers' diarrhoea, pediatric diarrhoea, inflammatory bowel disease and irritable bowel syndrome. In the future probiotics may contain mixes of strains with complementary characteristics, tailormade for different gastrointestinal diseases and vaginosis. Strains of probiotics may also be useful as delivery systems for vaccines, immunoglobulins and other protein based therapies. (Reference: Lactobacillus Molecular Biology: From Genomics to Probiotics ISBN: 978-1-904455-41-7)

Probiotics science resource at Probiotics and current topics on microbiology research at the Microbiology Blog

What are Probiotics

by G. W. Tannock.

What are Probiotics A probiotic is a live microbial feed supplement which beneficially affects the intestinal microbial balance. Although referring to the supplementation of animal feeds for farm animals, the definition is easily applied to human probiotics. The major consumption of probiotics by humans is in the form of dairy-based foods containing intestinal species of lactobacilli and bifidobacteria. Consumption of the probiotic affects the composition of the intestinal microflora. This effect of the probiotic on the intestinal ecosystem, impacts in some beneficial way on the consumer. A number of potential benefits arising from changes to the intestinal milieu through the agency of probiotics have been proposed:

  • increased resistance to infectious diseases, particularly of the intestine
  • decreased duration of diarrhoea
  • reduction in blood pressure
  • reduction in serum cholesterol concentration
  • reduction in allergy
  • stimulation of phagocytosis by peripheral blood leucocytes
  • modulation of cytokine gene expression
  • adjuvant effect
  • regression of tumours
  • reduction in carcinogen or co-carcinogen production

For further information please visit the Probiotics Book

Further reading