SACPA hears about relationship between gut and brain health

By Al Beeber - Lethbridge Herald on May 31, 2024.

Herald photo by Al Beeber Chelsea Matisz of the University of Lethbridge talks to SACPA on Thursday about the relationship between gut and brain health.

LETHBRIDGE HERALDabeeber@lethbridgeherald.com

The connection between gut-brain health was the focus of Thursday’s Southern Alberta Council on Public Affairs discussion in the dining room of the Lethbridge Senior Citizens Organization.

As listeners ate lunch, speaker Chelsea Matisz gave an in-depth examination of how internal systems work in impacting that health.

She talked about the role of the Vagus nerve and the sympathetic and para-sympathetic arms of the nervous system. And how gut-brain health can be helped through diet, particularly by the consumption of more fibre which is crucial for the body to produce short-chain fatty acids which are used by the gut to produce energy.

Bodies don’t absorb fibre so the fibre that gets through the small intestine reaches the colon where the highest density of bacteria on the planet exists. And that bacteria metabolizes dietary fibre, creating those short-chain fatty acids that are absorbed by gut cells and used as an energy source.

The sympathetic system, the audience heard, controls the so-called fight or flight responses. This is a system people can control. The parasympathetic system, on the other hand, regulates the rest and digest functions of the body.

And Matisz suggested audience members look at the Bristol Stool Chart which is a medical aid that classifies stool into seven different groups. This can help tell people if they have enough fibre in their diet.

Matisz is a postdoctoral scholar at the Canadian Centre for Behavioural Neuroscience at the University of Lethbridge, where her research seeks to understand how gut health affects brain health and mental health. She has a masters in Parasitology from the U of L and a PhD in Gastrointestinal Studies from the University of Calgary.

Research has shown that disruptions in the gut-brain axis can contribute to a range of health issues including inflammatory bowel disease and irritable bowel syndrome as well as neurological problems such as depression and anxiety.

Matisz has been interested in parasites and how the gut and brain communicate with each other, she told the audience.

“Really there’s been a revolution in terms of how our understanding of how the gut and brain communicate with each other because of the technology that allows us to understand micro-biomes in our bodies,” she said.

Her discussion addressed how the gut and brain communicate with each other and how that knowledge can be leveraged to improve health and wellness.

The gut, she said, is the tube that runs from the “gums to the bum.” The gastrointestinal tract is compartmentalized into different compartments for different functions, she said, referring to the mouth, esophagus, stomach, and small and large intestines.

Related to the process of digestion are different organs which are important for metabolism and the production of enzymes such as bile, trypsin and hydrochloric acid, she said.

“Digestion is an extremely complicated process,” with enzymes needing to be produced not only at the right time but also in the right amount, Matisz said.

People don’t want a lot of hydrochloric acid in the stomach with no food there, for example.

The length of time food spends in different compartments is also important, Matisz said.

When food is in the stomach and isn’t being emptied at the right rate, that can cause problems such as reflux and heartburn. And if food moves through quickly through the colon that can cause diarrhea and if too slowly, constipation.

So regulating the enzymes that are produced in the right amount and the right time and the amount of time it takes for food to move through the body – called motility – is an important process, she said.

Matisz said the gut has multiple layers within it and between them are the submucosal plexus and the myenteric plexus which are the gut’s “brains.”

This system consists of two to three thick layers of neurons that extend the entire length of the gastrointestinal tract.

The myenteric plexus controls the movement of food while the submucosal plexus controls absorbing and secretion, Matisz said, noting there are more neurons in the gut than in the spinal cord.

Fifty per cent of a body’s dopamine and 90 per cent of a body’s serotonin are in the gut “so it’s a very fascinating organ,” Matisz said.

A thin layer of certain cells called enterocytes absorb nutrients as they get broken down into glucoses and amino acids which enter the blood stream, and in the case of fatty acids the lymphatic system.

One per cent of enterocytes is called an entero-endocrine cell, she said, which function as the gut’s taste buds. They have a tuft on the top which senses nutrients. On the bottom part of these cells, they are packed with different types of hormone. One subtype of entero-endocrine cell, called an L cell, releases a hormone called glucagon-like peptide which enters the blood stream, gets into the brain and tells a certain region of the brain to stop eating.

Scientists, said Matisz, have managed to develop something that looks and acts like GLP in the gut, a drug that is important for people who manage Type 2 diabetes, a drug known as Ozempic.

Matisz said people can consume foods that stimulate L cells to produce glucagon-like peptides including avocado, olive oil and nuts which she said “are all excellent ways to stimulate these L cells to produce GLP to help suppress appetite and help regulate insulin.”

Other foods can inhibit the enzyme that will break down GLP such as black beans so it stays in the body for longer.

“This is just one of the cool ways to use food and our diet to sort of hack the system in a way to take advantage of the fact that there are sort of nature’s Ozempic available to us in our body.”

The other important job of the gut aside from digestion is defence, said Matisz.

Some things put into the body might come with environmental toxins or pathogens so bodies have to be good at defending against them.

Seventy to 80 per cent of the immune system is in the gut, she said.

Enterocytes form the gut barrier between the outside environment and the body. And these cells need tight junctions to hold them together. Maintaining that tight junction is important, she said. And that’s where those short-chain fatty acids come in handy because they provide the energy to maintain that tight junction.

The gut and brain also talk to each other through the immune system. Any type of inflammation in the periphery of the body is going to drive inflammation in the brain, said Matisz, noting everyone has experienced that.

Changes in behaviour occur because of changes in the brain, Matisz said, calling neuro-inflammation “a beautiful way that our bodies have developed to help with the immune response against the pathogen making you sick.”

Mounting an immune response is energetically expensive so symptoms like lethargy, fatigue and social withdrawal are a clever way the body has developed to force a person to rest and recover and divert energy resources to the immune response.

When gut and neuro-inflammation go away people feel better but that isn’t the case for people who suffer from many chronic inflammatory diseases, said Matisz, who studies IBD in mice.

A diverse range of diseases and disorders are co-morbid, meaning they co-occur with anxiety, depression and cognitive disfunction at rates much greater than the health population, Matisz added.

“The psychological burden of disease is one component that leads to these mood disorders but there’s also that biological component, that peripheral neuro-inflammation driving neuro-inflammation in the brain and that is actually changing neuro circuitry in the brain and it’s changing neuro circuits to the point that even when people are in remission from disease, you still have elevated levels of anxiety and depression.

“And what’s really remarkable is that people that suffer from some of these diseases, if you’re in remission and you experience a kind of pyscho-social threat” such as a job loss or a fight with a partner, “those kind of stressors are actually enough to trigger inflammation in your gut and trigger a flare-up of disease or perhaps a bout of diarrhea or gastro-intestinal pain and that really highlights this bi-directional communication that is happening between the gut and the brain.”

A third way guts and brains talk is through the nervous system, she said in a discussion about the Vagus nerve which innervates many visceral organs including heart, lung, liver and gut. It has a huge bundle of neurons and 90 per cent of them are called sensory neurons which take information from those organs to the brain, Matisz said.

The brain processes that information and the remaining 10 per cent of the nerves in the Vagus nerve relay effective responses including telling the heart rate to slow down and the gastro-intestinal tract to increase motility.

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