Yogurt-probiotics do not have a positive effect on the intestinal microflora
Last reviewed: 16.10.2021
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If bacteria contained in yoghurts and have a positive effect on the microflora of the human intestine, then they make this an incomprehensible way in science. Researchers have not been able to detect the slightest shifts in the microflora of the human intestine after the systematic use of probiotic yoghurts.
But how is advertising conducted! "The bacteria that are contained in the product will help you to restore the microflora and normalize the intestine" ... The irony is that if bacteria in yogurt and help, then in some unknown way, about which science knows nothing. Microbiologists from the University of Washington in St. Louis (USA) came to the conclusion that bacteria in yogurt have no effect on the microflora of the gastrointestinal tract and certainly can not replace it.
Scientists have involved in the study seven pairs of identical twins. One of the twins of each pair, with the same diet, regularly consumed a popular brand yoghurt containing five bacterial strains. Since the twins are genetically identical, the influence on the intestinal microflora of other factors, except for the diet, has been minimized.
Over time, microbiologists tested the DNA of the intestinal microflora from volunteers. It turned out that lactic acid bacteria from yogurt did not affect the species composition of the "indigenous" bacteria. Jeffrey Gordon - project manager, said he was not surprised by the result of the study. Dozens of trillions of bacteria live in the intestine, and the few billions that come with yogurt can hardly affect the existing system of the intestinal microflora of a person.
The results were confirmed in animal experiments. Scientists received gnotobiontnyh mice, devoid of their own microflora, and populated in their intestines 15 species of microorganisms that live in humans. After that, the mice were again fed with yoghurt bacteria. Again, yoghurt bacteria did not have any effect on the composition of the rooted intestinal microflora of animals. However, as scientists write in the journal Science Translational Medicine, it was possible to detect changes in the genetic activity of resident bacteria: they have increased the activity of genes responsible for the processing of carbohydrates. The same increase in activity was observed after entering the intestine and one of the "external" bacteria, Bifidobacterium animalis lactis.
Recently, manufacturers who are engaged in the creation and promotion of "bioactive" products are increasingly being criticized, demanding the confirmation of the usefulness and "bioactivity" of yoghurt products. But the fact is that to select an adequate experimental system that would assess its effect on the same microflora is rather difficult. Gnotobiont animals could serve in this matter, since in this case all the factors that affect their microflora are under the control of the researcher. But, apparently, you need to be prepared for the fact that not all yogurts will be equally useful.
So far, the objections to the results are that there were too few people in the study, and there was not a sufficiently detailed analysis of bacterial DNA. As for experiments on animals, here it is indicated that the intestines of mice are still adapted to inhabit in it own, rather than imposed (human) microflora. It is possible that the bacteria from yogurt still have a positive effect on the well-being of a person, that's nothing science knows about this.