Gut health: why it matters beyond digestion

The microbiome: an internal ecosystem

Your digestive tract houses trillions of microorganisms, bacteria, fungi and others, collectively called the gut microbiome. They sit in a balance, and they do a surprising amount of work.

Every ecosystem depends on balance, and this one is no different. When it is disrupted, digestive symptoms may follow, and other parts of health can be affected too.

The gut and the immune system

A large proportion of the body’s immune tissue sits inside the gastrointestinal tract, in what is called gut-associated lymphoid tissue, or GALT.

This network is interacting all day with food, bacteria and everything else entering the digestive system, and its job is to tell the difference between something harmless and something that warrants a response. Get that wrong in either direction and there are consequences.

Where digestive health is compromised, immune regulation may be affected as well, which is part of why gut health is increasingly considered in people living with allergies and inflammatory conditions.

The gut-brain connection

Have you noticed that stress can upset your stomach, or that months of digestive symptoms leave you mentally flat? That is not imagination. The gut and brain are in constant two-way communication through what is called the gut-brain axis.

Around 90 to 95 per cent of the body’s serotonin is made in the gastrointestinal tract. That serotonin mostly serves digestive function rather than mood directly, so it is not the tidy explanation it sometimes gets turned into, but it does show how closely the two systems sit together.

Poor gut health has been associated with symptoms including:

• Brain fog
• Fatigue
• Reduced concentration
• Poor stress resilience
• Low mood

All of those have many possible contributors, and I would not pin any of them on digestion alone. But digestion is one area worth actually looking at rather than assuming.

Irritable bowel syndrome

IBS is one of the most common gastrointestinal presentations in practice: abdominal pain, bloating, diarrhoea, constipation, or an alternating pattern of both.

Because the gut and brain communicate so closely, doctors sometimes prescribe medications originally developed for mental health conditions to help with IBS. Used this way they are described as gut-brain neuromodulators, and the aim is to reduce visceral hypersensitivity rather than to treat mood. Tricyclic antidepressants carry the strongest evidence for symptom relief; SSRIs are considered in some people, particularly where anxiety or depression also exist.

I raise this not because it is something I prescribe, it is not, and it belongs with your GP or gastroenterologist. I raise it because it shows how seriously the gut-nervous system relationship is now taken in mainstream practice, and why looking at both makes sense.

How I work with digestive symptoms

Digestive symptoms rarely have a single cause, so the first consultation is a full hour and covers:

Looking beyond the gut

The question I am asking is not only how to improve digestion. It is what may be contributing to these symptoms, and how that might be affecting the rest of you.

The gut is closely connected to the immune system, the nervous system, the skin and a good deal else. It is not the answer to every health concern, and I am suspicious of anyone who says it is. But supporting digestive health is often an important part of the picture, and it is usually where I start.

Related: the gut-skin connection, in the allergies and skin article

This article is general information, not a diagnosis or personal health advice. Blood in the stool, unexplained weight loss, persistent vomiting or a marked change in bowel habit should be assessed by your GP without delay. Keep taking prescribed medication and keep your medical appointments.