The Ministry of Health warns
Useful probiotics become harmful when they get into the intestines
Yulia Vorobyova, Vesti
Recently, more and more scientists are beginning to doubt the benefits of probiotics – functional living microcultures, which, as a rule, are contained in special additives and dairy products.
Manufacturers of such products claim that "bacterial prevention" improves the health and functioning of the intestine. In fact, probiotics do not justify the title of beneficial microorganisms: their effectiveness, according to recent data, is greatly exaggerated. Moreover, an excess of probiotics can even affect the ability to think clearly.
A new study by American scientists has replenished the piggy bank of revealing scientific papers. A team from Washington University School of Medicine in St. Louis has found that beneficial microorganisms entering the intestine can eventually turn into useless and even harmful, according to a press release from Probiotic bacteria evolve inside micah's GI tracts.
Experts explain that in the microbial world, the line between the "light" and "dark" side is blurred. Bacteria are able to quickly adapt to new conditions by changing their behavior. And probiotics are no exception.
"If we are going to use living beings as medicine, we have to recognize that they are adapting [to the new environment]. This means that what gets into your body will not necessarily remain the same even after a couple of hours. This is not a reason to abandon the development of therapy based on probiotics, but it is a reason to make sure that we understand how and under what conditions they change," says the lead author of the work, Professor Gautam Dantas.
His team decided to study in detail the behavior of a widespread probiotic strain of E.coli E.coli Nissle 1917.
Scientists have observed how these probiotics behave in the intestines of mice. Rodents were divided into four groups and various types of microbiota were formed in them. One group had a diverse and healthy intestinal community; the second group had a microbiota with limited diversity characteristic of an unhealthy intestine; the third group also lost some types of bacteria due to antibiotic treatment; the fourth group had a "clean" intestine devoid of microorganisms.
At the same time, part of the animals from each group received ordinary food with a high fiber content, the second part – food rich in fats and sugar (imitation of the "Western diet"), and the third part was fed both. The rodents also received a probiotic supplement.
Five weeks later, experts analyzed the DNA of beneficial bacteria from the intestines of mice.
Probiotics in the body of healthy animals that ate normal food did not show any obvious changes. But the bacteria that got into the intestines of mice with less healthy diets and less diverse microbiota showed adaptive changes.
So, with the "Western" diet, probiotics mutated to eat a large amount of sugars of different types. And those microorganisms that encountered antibiotics quickly developed resistance to them.
Meanwhile, some "useful" bacteria acquired the ability to eat intestinal mucus, which caused damage to the health of the "host".
"Against a healthy background with a large [microbial] diversity, we did not notice significant adaptations, perhaps because this is the same background to which the E.coli Nissle strain is accustomed. But it should be remembered that probiotics are not so often used by people with a healthy microbiota. We will use them in sick people whose microbiota is not so diverse. And this seems to be the condition when the probiotic will evolve," notes co–author Aura Ferreiro.
However, scientists are optimistic. They have gained valuable knowledge that will help develop personalized approaches to the treatment of various diseases and disorders of the intestine.
"Evolution is a given. Everything will develop. We don't need to be afraid of that. We can use the principles of evolution to develop the best therapeutic tool that will be carefully adapted for the people who need it. This is an opportunity, not a problem," Gautam Dantas is sure.
Actually, his team has already taken the first step in this direction. Based on the data obtained, the researchers developed a probiotic therapy for a disorder called phenylketonuria. Patients with this disease are unable to metabolize phenylalanine, an amino acid that can cause brain damage in high concentrations. Such people are forced to adhere to a strict diet, because a dangerous compound for them is contained in many products.
Scientists have provided E.coli Nissle bacteria with a gene that is responsible for the breakdown of phenylalanine. With the help of genetic modifications, mice were deprived of the ability to process this substance independently, and then fed them probiotics with a new "ability". After just a day, the levels of phenylalanine decreased in some rodents by half (decay products began to be excreted in the urine).
It is noteworthy that after a week of such therapy, scientists did not detect any signs of adaptation in probiotics. Therefore, the team hopes that the new "bacterial treatment" strategy will be safe and effective at least for short periods of time.
In the future, experts intend to explore the possibility of bioengineering "settings" and other probiotics.
A scientific article based on the results of this work was published in the journal Cell Host and Microbe (Crook et al., Adaptive Strategies of the Candidate Probiotic E. coli Nissle in the Mammalian Gut).
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