Back at the beginning of the 20th century Nobel laureate Ilya Mechnikov suggested that the intestinal microflora can determine the physical and even mental health of a person. The technologies of that time did not allow confirming or refuting this theory, but today we can say with confidence: the Russian biologist was right in his guesses. Over the past few years, a huge amount of data has accumulated about the microorganisms that inhabit us. It turned out that there are much more of them than expected, they are responsible for many important processes and, in fact, live in absolute symbiosis with humans: we cannot live without them, and they - without us.
Text: Vasilisa Kirilochkina
What is the microbiome made of?
Several years ago, against the background of a surge of interest in the topic, instead of the usual concept of microflora, more and more modern terms began to sound more often: microbiome and microbiota. “The microbiome is the ecosystem in which microorganisms live and the resources they use. There are microbiomes of soil, ocean and other natural niches. Humans also have different microbiomes - skin, intestines, respiratory tract, and urinary tract. And microbiota, or microflora, refers to the organisms themselves (bacteria, fungi, viruses, archaea and other protozoa) that can be isolated from this ecosystem and studied,”explains Elena Ilyina, Doctor of Biological Sciences, Head of the Department of Molecular Biology and Genetics of the Federal Scientific clinical center of physical and chemical medicine of FMBA of Russia. However, the terms “microbiome” and “microbiota” are often used interchangeably.
The main impetus for new microbiota research at the beginning of the 21st century was the development of genomic sequencing, a method that allows one to read the genome of an organism. The more accessible and accurate this technology became, the more microbiologists used it in their research. Gradually, the idea of the composition of human microflora changed - it turned out that it is much more diverse and mysterious than previously thought. For example, there are 150 times more bacterial genes in our body than our own. In this sense, a person can be considered a superorganism - not one, but a whole group of synergistically interacting living beings. This term is mentioned in the book by the American biologist Rodney Dietert, who formulated the idea that we are not only humans, but also microbes.
At the same time, the composition of the microbiota of different people varies greatly - it depends on lifestyle, environmental factors, nutrition and many other aspects, starting from the moment a person is born. A large European study was devoted to this phenomenon, the results of which were published in the journal Nature in 2011 - then scientists for the first time identified the so-called enterotypes of urban residents from all over the planet. It turned out that in different people, regardless of the continent and country of residence, different groups of bacteria prevail in the intestines - for example, bacteroids, ruminococci and others - and all this diversity can be considered normal variants. But today, just eight years after the discovery, enterotypes are being addressed less and less - because a huge new array of data has accumulated, indicating an even greater diversity of microbiomes and their effects.
The main and constantly updated database on the biological diversity of organisms living inside us today can be considered the Human Microbiome project, which was launched in the bowels of the US National Institutes of Health back in 2007. During the first phase of the project, which lasted until 2014, scientists studied and described the composition of the microbiota of the intestines, skin, genitals and other ecological niches of the human body. The second phase, which continues to this day, is devoted to the study of the influence of this microflora on our health.If you summarize the data from this project and other studies around the world, it turns out that the microbiome affects just about everything. And we are especially strongly dependent on the state of the intestinal microflora. In particular, it has been linked to autoimmune inflammatory diseases like Crohn's disease and ulcerative colitis - but that's just the tip of the iceberg. The intestinal microbiome can affect the work of the cardiovascular system, increase the risk of developing diabetes mellitus, influence the functioning of the brain and the immune system - for example, the effectiveness of therapy for certain cancers is highly dependent on how the intestinal microflora reacts to it.
Is there a dysbiosis
We know a lot about the microbiome, but have not yet figured out the main thing - its real composition. We still do not always understand what they see super-powerful machines for decoding the genome. “Sometimes, going deeper and deeper, we find dark matter - fragments of DNA that we cannot attribute to anything living, known to us. We have never seen them before and do not understand their nature. There are 20-30 percent of such areas of the entire metagenome of organisms living in us,”says Ilyina.
It is logical that if we do not understand the composition of normal microflora, which is also different for all people, then no diagnosis of "dysbiosis" can exist. In evidence-based medicine, it is not. Although in the post-Soviet space they like to explain the undesirable effects of antibiotics by dysbiosis, trying to treat the latter, authoritative medical organizations call them simply "antibiotic-associated diarrhea"; in some cases, we are talking about an acute infection with the bacteria Clostridium difficile, but again not about dysbiosis or imbalance of microflora.
Unfortunately, in post-Soviet countries, both the diagnosis of "dysbiosis" and the recommendations for examination for it can be found often. This practice is criticized by both scientists and doctors. Gastroenterologist Aleksey Golovenko directly writes in his telegram channel that today the recommendation “to make feces culture for dysbacteriosis” is an indicator of an unsubstantiated approach to diagnosis and treatment: “The norm for the number of different bacteria in the feces was determined by unknown means. And the very concept of a “normal” composition of the intestinal microflora is nonsense. Microflora is more individual than a fingerprint. " Ilyina agrees with him: “I think that in scientific terminology, dysbacteriosis will take on a sound only when we switch to personalized medicine - we will monitor a person from birth and throughout life and understand what flora is normal for him, and when an imbalance occurs.”
Another dubious, but popular exclusively in Russia test for the composition of microflora is the CMS blood test, also known as the Osipov microbiota test. Each type of bacteria has its own set of fatty acids, and they can be identified using chromatography with mass spectrometry - it is on this technology that the method of scientist Georgy Osipov is based. Fatty acids are isolated from the blood, identified and based on the data obtained, the composition of the microbiota is determined. The accuracy of such a test raises questions. “Some fatty acids from the intestinal microflora can indeed be absorbed into the blood, but not all, so the sample is not representative,” explains Ilyina.
Do I need to look for my norm
In adulthood (from about 18 to 65 years old), our microbiome is incredibly stable - by adulthood, it reaches balance and maintains it, despite external influences - otherwise we simply would not survive. This state of the intestinal microflora is considered dominant (it is also called constitutional); the composition of the microbiome during temporary changes is called transient, or transient. “It is known that bacteria from probiotic preparations do not take root, but pass as a transient flora. They can have a short-term effect, but they will not occupy any ecological niches,”says Ilyina.After a course of antibiotics, probiotics can sometimes help recover a little faster, although not everyone - research shows that people respond differently to such interference in the gut microbiome. Be that as it may, do not expect that a daily serving of live yogurt will change the microflora in the long term.
To understand at least an approximate composition of your dominant microflora, you can do a genetic test of the microbiota. The catch is that it only shows the current composition of the gut population. To compare it in different periods and highlight the "backbone", you will have to take such a test several times a year (and it costs more than ten thousand). At the same time, the practical application of the knowledge gained is not yet clear: it is possible to diagnose clinical diseases in other, more accessible ways. As Alexei Golovenko notes in his blog, “The goal of any analysis is to change the treatment regimen. So far we cannot "plant" a specific missing bacterium in the intestines. No way. This means that we do not need even a full-fledged genetic test of microflora”.
How to take care of your microbiome
Today, the easiest and most affordable way to take care of the intestinal microflora is to adhere to a healthy lifestyle and, no matter how trite it may sound, to listen to the body. For example, it is known that increased sugar intake can actually negatively affect the microflora and promote the active multiplication of Candida in the body. But for some, a piece of cake is enough for this, while others will not experience problems from a box of cakes, washed down with a fanta. A healthy person can monitor their condition after meals, noting which foods the body reacts to especially sensitively. But, of course, when problems arise, you should not self-medicate - you need to contact a therapist or gastroenterologist.
In general, the recommendations for “caring for the microbiome” are general for everyone and surprisingly coincide with the recommendations for maintaining overall health: Eat plenty of fiber-rich vegetables and grains, do not overuse sugar, drink enough water, sleep well and exercise regularly. And with the help of food, you can improve your mood and fight stress - and this is not about food like ice cream, but about products that help bacteria to produce neuroactive substances and positively affect the functioning of the nervous system. The healthy list includes the same antioxidant-rich berries and fruits, tryptophan-rich cheese and bananas, nuts and fish high in omega-3 fatty acids.
PHOTOS: science photo - stock.adobe.com, Andrii Zastrozhnov - stock.adobe.com