“May the microbiota be with you” could have been a good greeting for the Star Wars characters. Less commercial than the classic “force”, it is true, but much more effective for practical purposes. After all, we now know that there is nothing like having a healthy and balanced collection of microorganisms by our side to enjoy good health , a robust immune system, an agile mind, good humor and an enviable life expectancy.
This is no exaggeration. The simple fact that in the human body there are ten times more bacterial and fungal cells – microbes – than eukaryotic cells – their own – should already make us suspect that they do not exactly play a secondary role. That if they are there in droves, it is for something. And that something includes nothing less than contributing to the maturation of the immune system, absorbing nutrients or preventing pathogens from invading us .
How tiny beings handle such serious and complex matters can be explained in two strokes. ” Gut microorganisms help us digest what we eat and ferment foods, especially those rich in fiber,” explains biologist Natalia Arias, from King’s College London, to VERY. And in that process they produce huge amounts of short chain fatty acids ”. Said fatty acids –acetate, propionate and butyrate–, in addition to serving as an instant energy source, “regulate the activity of the immune system and affect the production of hormones and the neurotransmitters dopamine, GABA and serotonin”, adds Arias. That explains its enormous impact on a cognitive and emotional level. As the researcher reminds us, it is not for nothing that the microbiota is known as “the second brain” .
The point is that, every time we choose what to eat, we also decide with what army of intestinal microbes we face the world, a whole exercise of responsibility that is better carried out if we take into account that what contributes the most to a healthy microbiota is ingesting products of vegetable origin, little processed and very varied . In French it is known as the rule of the three Vs: végétal, vrai, varié . On the contrary, abusing the ultra-processed ones drastically reduces intestinal diversity.
Although it is far from new to science, Arias still has astonishment in his voice when he explains that, if we eat poorly and the microbiota becomes unbalanced – what is known as dysbiosis -, we can end suffering from anxiety, depression, autism, attention deficit disorder and other mental illnesses . “Realize what this means: that, among other things, what we eat can make us feel more or less happy,” he emphasizes.
However, his current research is going in other directions. Arias has spent years trying to understand “the close relationship between the food we eat and certain metabolic disorders such as diabetes, non-alcoholic fatty liver or even premature death,” he summarizes. Assuming that the bridge between what we eat and these diseases is precisely the intestinal microbiota.
Fatty liver is what makes Arias sleep the most. It is a pathology generated by the persistent abuse of fat and cholesterol intake. Today, it affects one in four Spaniards. A fact to get serious if we take into account that, when it escapes all control, it can lead to cancer. The microbiome, the liver, and the brain form an interesting trio. “In an experiment with animals that we carried out jointly with the Institute of Dairy Products of Asturias (IPLA-CSIC) and the University of Oviedo, we showed that, after a few weeks subjected to a diet rich in fat and cholesterol, their memory failed. work, they were apathetic towards social relationships and were depressed, ”explains Arias. In addition to having a diseased liver.
When they took a look at their brains, they found major changes in metabolic activity and neurotransmitter levels. Going deeper, the researchers concluded that the population of a bacterium called Akkermansia muciniphila had declined in the guts of these fat-stuffed animals. “So we gave them this microorganism to eat to see what happened and, surprise! The cognitive deterioration reversed, the depression disappeared,” explains the researcher. We were impressed, because mobilizing a single family of bacteria corrected brain failures at a stroke , ”he says. There was no need to restore balance to all bacterial populations, as had been done in previous attempts.
It is clear, concludes Arias, that ” the gut-liver-brain axis has an impact on behavior and cognition , and on which we must, and want, to continue investigating.” For now, he hopes to be able to confirm soon that the Akkermansia muciniphila bacteria helps prevent or treat Parkinson’s and Alzheimer’s early.
Both these two neurodegenerative diseases and aging are usually accompanied by an alteration of the balance of the intestinal flora. That means that the good bacteria tend to decline, while the most harmful ones grow in number. The latter promote inflammatory processes in which cytokines are produced. Or what is the same, low molecular weight proteins generated during the start-up phase of the immune response to regulate the amplitude and duration of inflammatory processes.
“Our problem is that, over the years, we intend to continue eating the same as when we were young, but it is neither advisable nor healthy,” reflects Arias. It would be better for us to start filling our pantries and refrigerators with foods that nutritionists have found anti-inflammatory effects ”.
Adapting our diet over the years would be much easier if we had biomarkers that periodically allow us to take the pulse of the intestinal flora and know how it evolves. And those are precisely Arias and his people.
If they succeed, they would have two options to rebalance the unbalanced microbiota at any point in life. Either consume foods with anti-inflammatory properties – broccoli, grapes, blueberries, apples, etc. – or resort to probiotics , that is, the ingestion of live microbes designed to maintain or improve the concentration of good bacteria in our digestive system.
Those same probiotics could help fight aging . Carlos López-Otín and Pedro M. Quirós, from the University of Oviedo, have been in charge of proving this. After analyzing the microbiota of Spanish centenarians, they identified an exaggeratedly high proportion of Akkermansia muciniphila . Look where, the same one with which Natalia Arias hopes to fight Alzheimer’s.
It also coincided that this same bacterium was decreased in mice with Progeria, popularly known as “Benjamin Button’s disease.” It is such an accelerated and precocious aging that children who suffer from it have wrinkled faces like an old man and rarely exceed eighteen years of life. In rodents, the pathology disappeared with a fecal microbiota transplant from a healthy mouse.
What paste the microbes that inhabit us are made of is largely defined at the beginning of life. “Do you know where they come from? – Arias asks me, to which she answers -: When women go to give birth, the baby opens its mouth when it comes out through the birth canal and is impregnated with the mother’s anal microbiota. –And she adds–: For this reason, if you can choose, natural delivery is preferable to cesarean section ”. How the composition of the microbiota then evolves is conditioned by breastfeeding – maternal or artificial – and by how the transition to solid foods takes place after six months of age . According to experts, in the first thousand days of a human being’s life we have an ideal window of opportunity to modulate its microbiota, with effects that are maintained for life.
But it is not only about taking care of your diet before the age of three. It is also convenient to let the little ones get dirty, play with the earth, roll around in the field. According to a recent Finnish study, it is enough for children to spend 90 minutes a day in contact with nature for four consecutive weeks for their body to notice it. Specifically, minors who grow up in these conditions have more anti-inflammatory proteins, in addition to a great diversity of microorganisms on the skin.
Yes, you read correctly, on the skin. Although the gut microbiota is the most popular, it is not the only community of microorganisms that we carry around. Without going any further, we recently learned that male genitalia are home to a bacterial congregation of tremendous importance, which in the case of the penis can be drastically reduced if circumcision is practiced.
If the microbes of the Fusobacterium periodonticum saga are calling the shots in your airways, you’re in luck. There is evidence that this bacterium could have an important protective role against covid-19. Of course, it should be borne in mind that respiratory health does not only depend on a protective bacterium emerging. The heterogeneity of the microbiome weighs more. In fact, the fact that a less diverse than normal pharyngeal microbial profile has been found in the elderly could explain why the elderly are more susceptible to SARS-CoV-2 infection.
In that sense, and although in the last year of the pandemic we have had no choice but to wear masks at all hours, assume social isolation and adhere to strict hygiene measures, our microbiota could end up being expensive. Portuguese researchers from the Center for Ecology, Evolution and Environmental Change (cE3c) of the University of Lisbon recently demonstrated that, since measures to slow the spread of the virus prevent the exchange of microbes between individuals, they can reduce diversity in the long run. of the microbiota and become more vulnerable to infections, including that caused by the coronavirus . A double-edged sword, in short.
Those who should not take their eyes off are the microbes in the mouth. Raúl Bescos, another brain that escaped to the UK, specifically to the University of Plymouth, knows this well. “It is estimated that we are talking about the second most diverse microbiota after the intestinal one, with around 700 different bacteria, and who knows how many viruses and fungi still unidentified”, this professor of Physiology tells VERY.
A nourished oral microbiota not only saves problems with cavities, gingivitis and periodontitis . Working in the laboratory, Bescos became aware of the close relationship between the abundance of nitrate-reducing bacteria in the human mouth and maximum oxygen consumption. “The higher this consumption, the lower the risk of cardiovascular disease,” he indicates.
Moreover, Bescos also recently demonstrated that “if you are one of those who practice sports but your mouth does not host a healthy and robust microbiota, it is very likely that the cardiovascular benefits of exercise are attenuated or disappear” .
If encouraging the bacteria in the mouth to live comfortably is crucial, how do we correctly choose which toothpaste and mouthwashes to use when brushing our teeth? “It is a good question – Bescos acknowledges when we ask it – but there is still a lot of information about it.” He tells us that he recently published a study on the consequences of using an oral rinse or mouthwash that included chlorhexidine, a powerful antibiotic. “We saw that after just one week of use the oral microbiota was significantly altered,” he says.
The changes were not exactly beneficial, because they increased saliva acidosis, a risk factor for gingivitis and periodontitis. In addition, the liquid destroyed bacteria indiscriminately, including many beneficial to health. “Right now there is a great interest on the part of pharmaceutical companies to develop rinses that contain prebiotics and probiotics , but not enough is known yet,” insists Bescos.
That feeling that there is still much to know about the microbiota is also shared by Natalia Arias. “Working in research, it always happens, and in this case much more,” he confesses. For each pathology linked in some way to the microbiota, we will need to find out nothing less the exact patterns of microbial populations that allow us to differentiate a healthy individual from another sick one. And be careful, because we are talking about a titanic task, taking into account that the microbiota has been linked to all kinds of diseases and disorders, from insomnia to autoimmune ailments, through autism, Alzheimer’s, Parkinson’s, depression, viral infections or hypertension.
“In addition, it is yet to be confirmed whether we have individual variability or whether we can apply the same treatments to all patients, ” adds the researcher. In many cases it is not even clear whether the variations in our microbial zoo are the cause of the pathologies or their consequence. To make matters worse, at the moment we do not know enough about the microbiota to use it as a diagnostic strategy. And, of course, it remains to be seen what are the cascades of events and biochemical changes that lie behind the close relationship between microbiota and mental health.
“There is work here for several lives,” laughs Arias.
