Researchers find that the probiotic bacteria found in many yoghurt drinks do alter the composition of the gut bacteria and also benefit certain aspects of metabolism.
The ability of probiotic yoghurt drinks to alter the composition of our gut bacteria as a whole has been questioned recently by a number of scientists and medical authorities. Their argument has been that while the probiotic yoghurt products such as Yakult and Actimel (popular in the UK which is a major market for probiotic products) contain around one billion bacteria, the human gastrointestinal tract contains around one hundred trillion so any health benefits are going to be marginal at best.
Although there is already ample research to demonstrate this is probably not the case, and probiotic products do have a marked influence on health, the traditional media is this week championing one new probiotic study in particular. The new research carried out at Imperial College London with the involvement of Nestle (a probiotic manufacturer), and published in the journal Molecular Systems Biology, demonstrates that such products do significantly influence the make-up of a person's gut flora and also have a number of other beneficial metabolic effects.
In the study mice that had been inoculated with human gut bacteria to give them a gut flora representative of that which would be seen in a forumla fed 6 month old human infant, were fed probiotic yoghurt drinks containing Lactobacillus paracasei and Lactobacillus rhamnosus strains of bacteria.
The researchers found that the probiotic drinks were able to significantly alter the composition of the gut flora, reducing number of some types of bacteria while increasing others, and that this subsequently improved many aspects of energy, fat, and protein metabolism.
Examples of benefits seen include the promotion of glycolysis, the initial stage in the process the body uses to turn carbohydrate into energy and similar improvements in the metabolism of amino acids (the "building blocks" of protein).
Additionally the probiotic drinks had an affect on the metabolism of bile salts which are produced by the liver and required for fat digestion and absorption. This effect could lead to applications in the treatment of liver disease as well as in weight loss since the amount of fat the body can absorb could theoretically be controlled by probiotic supplementation.
Previous research has suggested that probiotics can help prevent or treat bowel conditions such as ulcerative colitis and irritable bowel syndrome, as well as modulating immune function and protecting children against the development of allergies.
This new study is thought to be the first to demonstrate both an effect on gut microbe populations as well as systemic metabolic effects.
In the journal article the researchers conclude that "significant associations between host metabolic phenotypes and a nutritionally modified gut-microbiota strongly supports the idea that changes across a whole range of metabolic pathways are the product of extended genome perturbations that can be oriented using probiotic supplementation, and which may play a role in host metabolic health."
They also not that different metabolic changes were seen with the two different strains of probiotic bacteria tested.
It is hoped that the research will eventually lead to probiotic preperations that can be tailored to individual groups of people with different health complaints.
Source: F.P. Martin, Y. Wang, N. Sprenger, I. Yap, T. Lundstedt, P. Lek, S. Rezzi, Z. Ramadan, P. Bladeren, L.B. Fay, S. Kochhar, J. Lindon, E. Holmes, J.K. Nicholson (2008) Probiotic modulation of symbiotic gut microbial-host metabolic interactions in a humanized microbiome mouse model Molecular Systems Biology