Our health begins in the intestines

By Luis Collado Yurrita, Complutense University of Madrid

How many times in our lives will we have heard the typical comment of "My nerves have caught my stomach and that is why I have diarrhea." Or that other famous phrase, referring to students or opponents, from "The poor man has diarrhea from the exam nerves."

We say them almost without thinking. Ignoring that they have their origin in one of the famous sentences that Hippocrates de Cos (460 BC – 360 BC) formulated to his disciples, the Greek doctor considered one of the fathers of Medicine. Namely: "Health begins in the intestine." A maxim that has remained present and in force among health professionals, and even in the popular heritage.

Hippocrates was not misled. The prestigious scientific journal The Lancet recently pointed out that one in five deaths that occur worldwide is due to poor nutrition. Specifically to diets that do not include enough fresh vegetables, seeds and nuts. And instead, they don't skimp on sugar, salt and fats trans. Eating this "bad" not only affects health, but can even kill us.

Food is not the same as nutrition

At this point we are quite clear that the fundamental pillars of our health are proper food and nutrition. By food we understand the act of choosing and eating food, a voluntary and educable process that changes throughout our lives. By nutrition, the involuntary process by which our cells process the food we eat.

Well, the basis of nutrition are the processes that occur in our intestine thanks to the microorganisms that colonize it and which in jargon we know as intestinal microbiota. That gut microbiota is complex and varied. So much so that it is calculated that in our intestine we have more than 39 billion microorganisms, with a total weight of between 1 and 2 kilograms. There is nothing.

In healthy individuals, the protective microorganisms that make up the gut microbiota outnumber what we might call potentially harmful microorganisms. This balance of forces guarantees an adequate division of labor within the intestine and allows us, along with many other factors, to develop correct nutrition on the basis of adequate nutrition.

Personal and non-transferable microbiota

Before we are born, our intestine is sterile. The microorganisms colonize it either during childbirth or when coming into contact with the environment of the delivery room, if the birth is by cesarean section. The microbiota is configured and grows during the first days and months of life. Until it reaches a more or less stable composition in its diversity.

Of course, no two microbiota are the same. Its composition is personal and non-transferable. And it changes throughout life due to different factors, including the diet we choose to take, the consumption of drugs, the physical activity we carry out, including our own genetics.

Such is the importance of knowing the microbes that populate the intestines of each individual that in several countries research projects are underway to learn about the microbiota of their healthy population. In Spain, the Spanish Microbiome Project.

Exam stress and microbiota

At this point, the following question may come to mind: what happens when the intestinal microbiota is unbalanced and microorganisms potentially harmful to those beneficial to our health gain ground? When this happens, whether due to stress (such as from an exam), uncontrolled consumption of medications, poor sleep or dietary violations, what doctors call appears intestinal dysbiosis. And we started to have serious problems.

After all, intestinal dysbiosis can not only cause diarrhea. It has also been shown that it can be the starting gun for more complicated pathologies such as cardiovascular, tumor, autoimmune, respiratory diseases, etc. That is why it is essential to maintain an adequate intestinal microbiota. Because if it fails or deteriorates, our nutrition is affected and the risk of getting sick increases.

The list of diseases in which we know that the intestinal microbiota interferes is growing by giant steps. Without going any further, it was recently shown that the intestinal microbiota of autistic children is different from that of other children. If genus bacteria are scarce in our intestines Coprococcus and Dialister we became easy targets for depression, according to an article published last year in Nature microbiology. Furthermore, there is irrefutable evidence of the direct relationship between the composition of the microbiota and the risk of suffering from nerodegenerative diseases, including Alzheimer's.

We now have definitive evidence of how far our health begins in the gut (and in its microbiota). Thank you Hippocrates!

Luis Collado Yurrita, director of the Medicine department, Universidad Complutense de Madrid

This article was originally published in The Conversation. Read the original.