What you should know about the mind-gut connection

Cover Image for What you should know about the mind-gut connection
Reeva Misra
Reeva Misra

Dr. Emeran Mayer is a gastroenterologist who specialises in the communication between the mind and gut within the context of our environment. He is widely recognised as a pioneer of medical research into the brain, gut and microbe interactions and author of “The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts our Mood, Our Choices and Our Overall Health” and the more recent “The Gut Immune Connection”.

What is the Mind-Gut connection?

From an evolutionary standpoint, our nervous system and our gut have always been very closely connected, more so than any other organ. The Mind-Gut connection is essentially how the brain interacts with the digestive system (and vice versa). If you had to choose two organs that are the core of our being, I would say it is the gut and the brain. The gut itself is not just a digestive tube, it is also the immune system, the nervous system, and the endocrine system. In fact, we interact with the world more through our gut than we do with our skin.

Is the Mind-Gut connection accepted in traditional medicine?

Now much more so than 20, 10 or even 5 years ago. When looking for a thesis advisor at medical school, every professor I spoke to said that mind-gut connections can’t be studied–even though they admitted it was an important topic. After doing a rotation in gastroenterology at the Mass General Hospital at Harvard, I was convinced that I wanted to study how the brain interacts with the digestive system but I was surprised to see how big the disconnect was between this holistic concept and traditional medicine.

Why is mind and gut health so important?

Conventional Medicine views disease as a linear concept, going from point A to point B without looking at the holistic context beyond symptoms. This model has been very successful in treating infectious diseases, for example, where you identify a pathogen and develop an antibiotic to kill it. But, in reality, chronic diseases are not linear phenomena–they are dysregulations of a whole network, in which every organ in the body is interconnected, including the brain. For instance, if you are suffering from obesity, you also have a high risk of metabolic syndrome, of cardiovascular, liver and brain disease and cancer. This is no longer a linear phenomenon. Instead, you are looking at a paradigm of interconnectedness of every organ in the body. Chronic disease is a rearrangement in this global network that links every cell in our bodies together. Western medicine has not yet recognised that and as a result, nearly half of the US population are on chronic medicines. We are clearly not healing the disease–we are treating the symptoms and suppressing the issue. That’s when understanding the Mind-Gut connection becomes key.

How do environmental factors impact the Mind-Gut connection?

We have a hundred trillion microbes in our gut. In order to understand and model it, we have to apply a systems approach of interconnectedness. In chronic disease, the systems go way beyond our bodies. The microbes in your gut live off the food systems that cultivate the food in the first place–for instance, the plants in the soil. And if you pursue this consistently, you can all of a sudden see that we are all part of this gigantic interconnected system. I think what is happening with these viral epidemics is in some ways a systems phenomenon. We are attacking the normal system by cutting down the forests, encroaching on ecological habitats of wild animals, and overcrowding our cities. The way these diseases spread is not linear either–the whole world and system is affected.

Can the Mind-Gut connection help with anxiety and depression?

We know that around 95% of our body’s serotonin (the happy hormone), is stored in our gut. That serotonin communicates with the brain by stimulating the vagus nerve (a gateway to the parasympathetic nervous system), which in turn can reduce feelings of anxiety and depression. Serotonin is only one of the molecules we find in the gut though; tryptophan is broken down by the microbes that live in the gut into many different molecules that have a myriad of jobs in the body. However, we know that the rate of serotonin production is influenced by microbial activities–essentially, the microbes communicating with the cells lining our gut. These microbes kickstart the process for creating the serotonin which then gets released into the vagus nerve, carrying the signals to the brain and back into the gut. It’s a full circle process. Interestingly, the molecule that allows microbes to take up the serotonin is the same molecule that is triggered when you take an antidepressant. We are still at the beginning of understanding the mechanisms of this but what we do know is that there is a major link between what we eat, what the microbes do with our food and how it affects brain function.

How does stress affect the Mind-Gut connection?

Everybody now talks about having a healthy diet and what it does to your gut and microbiome. Very few people talk about the fact that negative emotions in the brain can do almost the same damage as unhealthy food. Chronic stress decreases the diversity of your microbes, and changes the behaviour and leakiness of your gut. Your gut is a mirror image of your emotions. We don’t listen and sense the effects of negative emotions or food on our gut on a daily basis. We tend to only notice the effects when we are in a lot of pain. People talk about the negative effects of the Western diet and obesity on cancer. You can imagine the combination of negative emotions and stress, plus the Western diet, will have twice the effect on increasing your risk of chronic disease. Typically in Western medicine, we don’t pay too much attention to the mind but it is really key to realise the importance it has on our wellbeing as a whole.

How can you improve your Mind-Gut connection for better health?

It’s firstly important to start thinking of our body as an interconnected network. How this network is constructed can then determine how resilient it is to disease. This programming mostly occurs early in life, typically in the first two years of our lives for the microbiome and the first 18 years for the brain. If your network is framed in a positive way, such as having grit when facing challenges, enthusiasm, passion, compassion for others, and eating the right sort of diet, you are likely to be more resilient later in life. This way of thinking offers an explanation for chronic diseases, even determining how long we live and how healthy we are.

As humans, we have this amazing ability to learn–our prefrontal cortex is incredibly plastic, providing our body with the opportunity to adapt and change to varying situations if we give it the opportunity. Just like the studies show, and particularly once you’re an adult, I think our health ultimately all comes down to attitude and diet.


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