G01022: An evaluation of probiotic effects in the microbial aspects

Study Duration: August 2002 to February 2004

Contractor: University of Reading

Probiotic supplements are now widely available for human use in the UK. These range from fermented milks to lyophilised forms containing both single and multiple bacterial strains. However, there is little comparative data on the survival of probiotics within the human gut. This project builds on existing information on the microbial content of currently available probiotics and assesses survivability. This will involve assessing the ability of individual probiotic bacteria to survive in models of each of the gastric, small and large intestinal regions and will look at effects on the colonic microflora balance.

This project has the following objectives these are:

1. A preliminary study of the contents of all probiotics on the UK market was completed in preparation for this project. This non-agency funded work involved the use of a number of methodologies to recover all live microbial strains. These strains were identified genotypically and phenotypically, and used in subsequent survival studies.

2. The selected probiotic bacteria will be treated with digesta that resemble the gastric and small intestinal environments. This will determine where in the GI tract probiotic organisms are able to survive.

3. A model of the human large intestine that reflects microbial events in the ascending, transverse and descending regions of the colon. The use of this model will not only gauge survival, but will allow the ability of probiotic organism to persist in the prescence of a complex microbiota to be assessed. Only strains that survive the upper gut challenges will be tested.

Findings suggests that not all strains of bacteria used in probiotic products survive through the entire digestive system, although at least one strain in each of the products tested survived beyond the stomach. The research does not show if or where probiotics might have an effect.
Scientists at the University of Reading used laboratory models of the human gut to imitate the conditions of the stomach, upper intestine and lower intestine.
Probiotic bacteria found in 11 different probiotic products were tested. Products included dairy and fruit juice containing live bacteria and dry preparations in the form of tablets, capsules and powder. All bacteria used were grown and their numbers standardised before each experiment began.
The researchers used a model to simulate the effect adding probiotic bacteria would have on the total number of bacteria in a typical human digestive system. Overall, adding bacteria from probiotics did not change the total number of bacteria in the gut.

The hard copies of the final report are available from the Agency’s Information Centre. To obtain a copy, please contact the Enquiry Desk, Information Services, Food Standards Agency (tel: 020 7276 8181/8182 or email: infocentre@foodstandards.gsi.gov.uk)

For any enquiries concerning this research project, please contact the relevant Programme contact or email: science@foodstandards.gsi.gov.uk