Microbiome and Mental Health

When we think of mental health, the brain comes to mind however, the GI tract, contributes to the optimal functioning of the brain and, therefore, to mental health.

Gut – The Second Brain

When we think of mental health, what comes to mind is the brain. Keeping the brain active, assuring it gets the necessary nutrients for its proper functioning, and sleeping well so it detoxifies. Doing all these things is crucial yet a vast line of research has shown that gut health also plays an important role in mental health. The microbiome or intestinal flora, living in the gastrointestinal tract, contributes to the optimal functioning of the brain and, therefore, to mental health.

Gut-Brain Axis

The first studies that correlated mental and gut health turned the world of psychiatry upside down, as Dr. Drew Ramsey states in his book Eat to Beat Depression and Anxiety. Intuitively we have always known about this relationship, so much so that we even have specific vocabulary on the subject: gut feeling, kick in the guts, have the guts, trust your gut, and so on. It is quite common cases of people that run to the bathroom at the first sign of stress. That’s due to the existence of a two-way highway where communication between the gut and the brain occurs. This pathway called the gut-brain axis, is a determining factor of survival and, of course, affects mental health.

Two-Way Communication

In addition to sheltering trillions of microorganisms, our gastrointestinal tract is also home to hundreds of millions of neurons. The intestines are the organ where the largest number of neurons outside the brain is concentrated. From the gut, neurons can send messages to the brain in a matter of milliseconds. It is through this communication that we know when we are full, and it is time to stop eating. Or when we are about to eat something spoiled, we feel nausea, which prevents us from eating. And when we do eat something spoiled, the GI tract immediately puts it out in the form of vomiting or diarrhea. All this is thanks to this two-way communication system.


The intestine is the largest organ of the mammalian endocrine system. It’s an interesting and multifunctional organ. In addition to its role in digestion, it secretes hormones and also plays a key role in the immune system. Around 70% of our immunity is in the gut which plays the role of mediator in when, where, and how pro-inflammatory molecules are distributed in the body. But the gut does not work alone, it relies on the help of the microbiome which is a community of trillions of microorganisms. They are bacteria, fungi, viruses, and other parasites that live in our GI tract cohabiting with us. There are more bugs in our gut than cells in our body.

Symbiotic Relationship

The understanding of the relationship between gut and mental health brings evidence that eating certainly helps the treatment of mental disorders. After all, nothing affects the microbiome more than what we eat. Although it sounds simple, the gut flora is incredibly complex. It is a sophisticated ecosystem of trillions of different microbes. Historically, we thought of microbes as pathogenic, or disease-causing, but less than 1% of all types of bacteria are pathogenic. Even those that are known pathogenic, such as candida or E. coli, only cause symptoms when their population grows beyond measure. If in balance, this symbiotic relationship works well. We need the microbiome as much as it needs us. If we’re healthy, so is it.

Microbiome and Mental Health

Diversity is important in every aspect of life. To be healthy we need our microbiome as diverse as possible, due to the different capacities of each species. A certain strain of microorganisms helps the digestion of nutrients, others produce enzymes that act in digestion and still others synthesize nutrients, such as B vitamins. For mental health, however, one group of microbes is particularly important, those that activate the neurons that release serotonin. Well, there are hundreds of millions of neurons in the gut and about 80% of those that release serotonin are there. These neurons are activated by a rare and unique type of single-celled organisms that strengthens the intestinal wall. Serotonin is the neurotransmitter that regulates mood and therefore directly correlates microbiome and mental health.

Diversity is Key

Ensuring the diversity of our intestinal flora is very important. In order to do that a healthy and varied diet that contains probiotics and prebiotics is a must. Probiotics are strains of beneficial microorganisms that we can ingest directly. They function as seeds of new species. Prebiotics are food for this population of good bugs and fiber-rich foods are the favorite dish of this invisible crowd.

No news to say that leafy greens, vegetables, and fruits are the top group of healthy fibers. If you want to strengthen your microbiome, start by eating lots of vegetables! Green should be the predominant color on your plate. Whenever possible eat vegetables and fruits with peels, which are rich in fiber. Make your plate as colorful as the rainbow. Legumes like beans, lentils, and chickpeas are excellent sources of protein and fiber. Nuts and seeds, in addition to being nutrient dense, also have a lot of fiber. All of these are excellent prebiotics, they feed the beneficial microorganisms, our good bug buddies.

Probiotics in Food

Although there is the possibility of supplementing probiotics it is possible to achieve the same results with a varied diet. Examples of good probiotics are fermented foods or foods produced through fermentation. Yogurt, kefir, kombucha, sourdough bread, and pickled vegetables, like sauerkraut. If you choose to supplement probiotics, make sure it’s a good quality one and check the manufacture date. Probiotics will only be effective if the microorganisms are actually alive inside the capsules. Like all living creatures, they don’t live long without food neither can survive differences in temperature.

Full Health

This amazing machine that we call the human body is all connected. It is no longer permissible to compartmentalize the systems for any type of treatment. We are an ecosystem and as such all parts are closely related in a complex not yet completely understandable way. The simplest thing you can do to make sure everything works well is to take care of what you let in. The quality of the water you drink, the air you breathe, the food you eat, what you put on your skin, and the feelings you let into your heart. Take care of your body!

Remember: Good is what makes you feel well!


If you want to know more about Nutritional Psychiatry, or how food can be treatment for mental illness read on the blog Mental Health.

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