It seems a joke, but it is not. Who would have supposed that the organ of our body with the greatest influence on diseases such as depression or anxiety , right after the brain, would be the intestines? Or rather what we call the guts, and that goes from the stomach to the rectum?
Depression is still a disease with many unknowns as to its causes, its treatment and its recovery process, and that is why several studies have tried to analyze in detail what it is that affects our brain to fall into that state. And some of them have suggested the surprising conclusion that the key (or one of them) is in the digestive system .
Our intestine has ‘its’ brain
It is called the enteric nervous system (SNE) and is a division of the nervous system that is responsible for directly controlling the digestive system . It is found in the layers of tissue that line the esophagus, stomach, small intestine, and colon, and scientists study how this bowel brain relates to our mood and behavior .
Its main function is to control the digestion of food, from the moment of swallowing through the release of enzymes that help break down food in the stomach to the control of blood flows that help absorb useful nutrients and discard unnecessary ones. Throughout the process, it communicates with our brain with profound results that are yet to be fully understood.
For a long time, scientists have considered that anxiety and depression contributed to cause problems such as irritable bowel syndrome and intestinal pathologies such as constipation , diarrhea, swelling, stomach pain and discomfort.
What happens in our guts also affects the brain
Now, new evidence shows that the relationship could be reciprocal , and that what happens in our guts also affects the brain, causing people suffering from any of these diseases is also more prone to suffer emotional imbalances, depression and anxiety.
The microbiota also affects us
In the focus of these studies is also the microbiota, the set of millions of bacteria living in them. Each one of us carries in our stomach and intestines about two kilos of these microorganisms.
Although its effect is almost always positive and necessary for the proper functioning of our body (help to digest food, eliminate compounds that could be toxic and prevent the proliferation of dangerous bacteria), they can also have an impact on how we feel.
These are two ways proven by science in which the microbiota affects our mental health.
From head to stomach, and back
We all know that our mental state affects our gut because we have felt it: when we are very nervous we feel as if someone were squeezing them, when we are very upset it is impossible to eat and one of the usual symptoms of depression is constipation.
It may not be so intuitive, but it is equally true that the same reaction occurs backwards, and that the state of our digestive tract affects our mood.
A team of scientists at the University College of Cork , in Ireland, tried feeding a group of mice with Lactobacillus rhamnosus, a type of probiotic bacteria common in yoghurts, and another group with a broth without those bacteria.
When then all the mice were forced to swim in deep water, the animals fed with probiotics struggled to stay afloat , while the others sank without resistance , indicating the mouse version of a depression. By placing them in an unfamiliar environment, the former more often dared to go out and explore than the latter, who stayed behind looking for consolation in their companions, a sign of anxiety.
Another study, conducted at the University of California Los Angeles, gave a group of women yogurts enriched in probiotics twice a day for four weeks; another group gave him non-probiotic dairy products and a third, his usual diet.
After four weeks, all went through a scan to measure their brain response, and it turned out that the group that had consumed probiotic yogurts showed different results in terms of brain functions both at rest and in response to a task of recognition of emotions.
The microbiota changes our personality
In another study , scientists at McMaster University worked with two different varieties of mice, chosen for their different personalities : one of them was shy and withdrawn, and the other more sociable and daring.
The scientists eliminated all the microbiota of both varieties by giving them antibiotics, and then they gave each one the intestinal bacteria of the other variety. And they discovered that at the same time they had exchanged their personalities : the timid ones were now sociable, and the sociables were now timid.
Can a diet cure depression?
No, it can not. At least there is no scientific evidence to date that this can happen. Although the direct relationship between the digestive system and emotional imbalances is increasingly well recognized, experts warn that not enough is known yet to establish a treatment.
However, there are some general dietary recommendations to prevent depression. These are the 5 keys that determined a study in this regard:
1. Follow patterns of traditional diets, such as Mediterranean , Norwegian or Japanese.
2. Increase consumption of fruits, vegetables, legumes , whole grains, nuts and seeds.
3. Include a high intake of foods rich in polyunsaturated fatty acids with Omega 3.
4. Substitute unhealthy foods for healthy and nutritious foods.
5. Limit the consumption of processed foods, fast food, industrial bakery products and sweets.