Alterations in intestinal bacteria are also related to type 1 diabetes or autism | Research in this field, still little studied, opens new therapeutic avenues for the future
Surely you don’t know it, but everyone microbes that live in your intestine represent around a kilo of what you weigh in total.
This population of bacteria is what is known as gut microbiota and in recent years it has proven to be so important that some researchers speak of it as a “new organ” either “second brain” of the human being. Yes: this self-sustaining ecosystem of “bugs” that you may find disgusting is necessary for the proper functioning of your body. And not only that: they are involved in the appearance of diseases as current as the atopic dermatitis, psoriasis, multiple sclerosis, celiac disease or type 1 diabetes, among many.
“Until now we know little because the human microbiota applied to medicine has only been studied for 10 years. But in the field of dermatology, already There are studies that show that patients with atopic dermatitis, psoriasis and acne have a different intestinal microbiota,” he explains. Vicente Navarro, director of the Chair of Human Microbiota and Infectious Diseases of the Catholic University of San Antonio de Murcia (UCAM).
“In neurology There is also a relationship between the microbiota and the disease described. Especially in the multiple sclerosis, Although this relationship is beginning to be investigated in the Parkinson’s, he Alzheimer’s, the epilepsy and the autism. And also in other inflammatory pathologies, such as Crohn’s disease (a chronic inflammation of the intestinal tract) or celiac disease. They are a very diverse group of diseases that generally share an immunological-allergic mechanism. That is why it is also said that the allergic rhinitis or the asthma could have to do with the intestinal microbiota,” he adds.
Developed countries
All of these diseases also have a similarity: they are typical of developed countries (especially those of the immunological-allergic type) and, also, a lot most prevalent in the last decades. “That is why it is thought that there is a component in diet of people – food has “bugs”, germs – that causes these diseases to appear. Those of us who live in developed countries have the same number of bacteria in our intestines as those in less developed countries, but much less biodiversity. Our biodiversity is almost half theirs. And, when this happens, in general this is related to the disease,” says Dr. Navarro.
Subscribe this idea Francisco Guarner, researcher at the VHIR (Vall d’Hebron Research Institute) in the digestive physiology and pathophysiology group, who assures that currently “There are diseases due to lack of bacteria.” “We have stopped feeding our ‘good’ bacteria. When we only eat white bread, eggs or meat and give up vegetables, we absorb everything ourselves and do not give work to those good bacteria, which end up atrophying. And then those that eat only intestinal mucus begin to proliferate,” says Guarner, who highlights that “big mistake” of the last 50 years has been the consumption of a “very industrialized diet”, from which “many natural fruits and vegetables” have been eliminated.
According to this expert, in addition “misuse” of antibiotics (they are necessary and save lives, yes, but have been used in a “not very selective” manner, he warns) has caused the massive death of millions of harmless bacteria in the attempt to kill only the one causing the current infection.
Probiotic preparations
But, if the altered intestinal microbiota is related to the appearance of diseases, Is it possible to reverse these ailments by modifying the microbiota?“In the psoriasis There is only one clinical trial that shows that with a probiotic preparation concrete [los probióticos son microorganismos vivos que pueden estar en los alimentos, medicamentos o complementos de la dieta]at 12 weeks, the patient tends to normalize the microbiota and, with this, the disease improves,” comments Dr. Navarro. This study was published a few weeks ago in the journal ‘Acta Dermato-Venereologica’.
Also with the celiac disease Progress has been made in children. “The disease improves with probiotics. There is a study carried out three years ago in the US on autism -patients with autism have altered microbiota- and it seems that with the use of a probiotic mixture the aggressiveness and hyperactivity of these children decreases,” adds Navarro. However, it is not possible at the moment to reverse autism spectrum disorder. Nor are diseases such as multiple sclerosis.
“In multiple sclerosis there are no clinical trials that include a large number of patients to try to modify this microbiota. There are laboratory studies with rats that show that, when a stool transposition from patients with multiple sclerosis, these rats begin to develop the disease. But there is no clinical trial that shows that using a probiotic cures the disease,” says the professor at the San Antonio Catholic University of Murcia.
Paradigm shift
All these findings, however, point to a path forward. “Are new therapeutic avenues. We are talking about diseases multifactorial cause. That is, we know that there are hereditary, inflammatory, environmental, autoimmune components… And it seems that one of those components is the intestinal microbiota. Researchers are using mechanisms to change the microbiota, and one of them could be diet”, Navarro says.
He himself explains that 57% of the genes what we have in the body are bacterial: That is, bacteria have managed to embed part of their genetic material in our genetic code and currently represent more than our human genes. “It is clear that so many bacteria must be involved in health and disease. It has been shown that the intestine influences fur and in the brain”, says the doctor. Because? “Because in the intestine we have the 80% of the lymphatic system, the unactivated nodes are in the intestinal mucosa. And, when they detect a new bacteria or one with some change, an alteration of the intestinal permeability.
This alteration allows harmful elements to pass into the blood through small holes in the intestinal wall, causing different damage at a systemic level. The main reasons why this pathology can occur are unbalanced diets, the antibiotic treatments, he stress or one excessive hygiene. “All this puts us in contact with something new that can change the world in the coming years. paradigm of many diseases,” concludes Dr. Navarro.
The “second brain”
He intestine It is, after the brain, the organ that has the most neurons: that is why it is also known as the “second brain” of the human being. “The intestine has a whole neuron network connected capable of making decisions without relying on the brain. He 99% what the intestine does, it decides to do itself,” he points out. Francisco Guarner, researcher at VHIR (Vall d’Hebron Research Institute) in the digestive physiology and pathophysiology group. An example: when a person lives a stressful situation, It is common for the large intestine to cause a diarrhea. “The intestine knows that you are stressed and prefers empty, as well as closes the stomach a little. The intestine is constantly making decisions,” adds Guarner.
So can our emotions affect the digestive system? Some, yes. “He stress It is a highly studied emotion because it occurs in other mammals. It also influences pleasure: There are many pleasure pathways that start in the intestine and go to the brain,” says Guarner. And the other way around: what is in our intestine influences our Personality traits? “Before 2010 the answer was no, but since that year the answer is probably yes,” explains the doctor.
In 2010 there was a mouse experiment through which it was proven that those rodents that were not colonized by bacteria had abnormal behavior: they moved a lot and stayed still in the middle of the cages. Normally the mice go to the corners, but the ones that had a altered microbiota They didn’t behave like that. “With this experiment it was seen that there was a behavior in the rodents that was not mediated by the genes of their parents, but by the bacterial colonization. This caused a lot of commotion, it is being studied but, at the moment, it is not clear what significance it has in the human being”, says this digestologist.
It has been seen, however, that people with some mental or neurodegenerative diseases(Parkinson’s, depression, Alzheimer’s) or with autism spectrum disorder They have abnormal bacterial colonization, although it has not been possible to reverse them even by correcting these alterations. Even so, other experiments have shown that anxiety can be reduced, for example, thanks to probiotic preparations.
What about hygiene?
As explained Martin J. Blaiser in the book ‘SOS Microbes’ (Debate), the “modern pests”(obesity, childhood diabetes, asthma, hay fever, allergies to certain foods, esophageal reflux, cancer, celiac disease, Crohn’s disease, ulcerative colitis, autism, eczema) have to do, for many people, with “hygiene hypothesis.” That is, many parents believe that because “we have left the world too clean,” their children’s immune systems have become inactive. But Blaiser does not share this explanation.
For this doctor the causes of these diseases are “the overuse of antibiotics in humans and animals, cesarean sections and the widespread use of disinfectants and antiseptics.” He also warns that the loss of diversity of our microbiome “affects metabolism, immunity and cognition.” “If we do not change our habits, we will find ourselves in an even worse situation. As gloomy as a blizzard in a frozen landscape, which I have called antibiotic winter,” he maintains.
Microbes, Blaiser says, help keep blood stable. blood pressure through specialized receptors located in blood vessels. “These sensors detect small molecules created by the microbes that line the intestine. Their response to these molecules regulates blood pressure. So, after eating, blood pressure can go down,” says Blaiser. According to him, it is very possible that in the future there will be better treatmentsfor hypertension using these bacteria.