Over the past five years, I’ve been on the board of the Gut Foundation that was founded a number of years ago by the legendary gastroenterologist, Professor Terry Bolin. The mission of the Gut Foundation is to educate the public regarding the importance of gut health, along with facilitating research into this important subject.

Over the past few decades, there has been increasing emphasis on the importance of gut health. The function of the gastrointestinal tract is to digest and absorb the nutrients we need, on a daily basis. The GI tract also excretes the waste products of digestion.

The process of digestion begins in the stomach and most of the nutrients are absorbed in the small intestine. Most of the excretion of waste occurs in the large intestine, culminating in the production of faeces.

There is increasing emphasis on the importance of a healthy gut microbiome. The gut microbiome is the extensive array of gut bacteria mainly found in our large intestine. There are up to 1,000 different species of bacteria living in our gut and, in reality, human beings are 10% human and 90% bacteria. The functions of the gut microbiome are:

1. To assist in host nutrient metabolism or in other words, work closely with the gastrointestinal tract to absorb appropriate nutrients.

2. In our modern world we are exposed to many synthetic chemicals and pharmaceutical drugs. The gut microbiome allows us to process these chemicals and excrete them when necessary.

3. One of the important aspects of a healthy gut is to have a healthy lining between the inner tube of the gastrointestinal tract known as the mucosal barrier or epithelium and the other layers of the gut wall. If this inner lining is working well, this promotes a healthy gut. Having healthy bacteria living in your colon and throughout the rest of the gut maintains this healthy lining, which prevents toxic nutrients being absorbed but allowing the absorption of healthy, necessary nutrients.

4. Many people do not realise that 70% of the immune system is found in the gut. Having healthy bacteria in the microbiome facilitates a healthy immune system.

5). Finally, having a healthy gut microbiome protects against pathogenic bacteria which can lead to disease. In a healthy gut, there are 85% healthy bacteria and about 15% unhealthy bacteria that are being controlled by the healthy bugs to prevent disease.

We cannot, however, see the gut in isolation and realise that all organs in our body are connected, working together to promote healthy living. There has been a recent emphasis on the gut-brain axis with many researchers now calling our gut the “second brain”. In the central and peripheral nervous systems, there are two types of cells. Firstly, the neurons that carry the electrical or chemical signals throughout the system and to the rest of the body. Secondly, the glial cells that act as the support and maintenance cells i.e. the immune system of the nervous system. Many researchers are now referring to this as the glymphatic system.

It is now well established that the glial cells play an important part in the gut nervous system, regulating how food travels through the gut.

A recent study published in the 'Proceedings of the National Academy of Sciences' demonstrated the strong connection between neurons and the glial cells and, in particular, the way these cells affect gut motility. Motility is basically the way the gut is constantly moving, similar to the movement of a worm. Without this constant movement, food and fluid would be stuck in different parts of the gut. With this constant movement, there is a free flow of food and nutrients throughout this system.

Food being propelled through the gastrointestinal system is called peristalsis and this is basically involuntary rhythmic contractions of the smooth muscle in the wall of the gut. This allows a bolus of swallowed food to move rhythmically through the gut allowing digestion, absorption and excretion of waste products. It appears that the very intricate nerve networks within the gut control all gut functions in a very specific regulated manner with strong communication between the brain and the gut.

At least 20% of the population suffer from some degree of gastrointestinal problems which includes anything from heartburn, dyspepsia and peptic ulceration to irritable bowel syndrome and the more serious inflammatory bowel conditions.

With a strong Gut-brain connection, it is no surprise that, with the increased complexity of modern living with all its concomitant stressors, people who are under significant stress will suffer more gastrointestinal diseases. Thus, the key to good gut health is not just swallowing a pill to suppress acid production in the stomach or taking a laxative to improve constipation but a more global and holistic approach to your life in general. A healthy gut is a great start to a healthy body.

1. Mohammad M. Ahmadzai, Luisa Seguella, Brian D. Gulbransen. Circuit-specific enteric glia regulate intestinal motor neurocircuits. Proceedings of the National Academy of Sciences, 2021; 118 (40): e2025938118 DOI: 10.1073/pnas.2025938118

Dr Walker is the current president of the Gut Foundation of Australia.