Why healthy gut function is so important for your brain

Our gut is in close contact with our brain, also known as the gut–brain connection. The health of your gut appears to be closely linked to both your physical and mental wellbeing. Did you know that a large proportion of serotonin — a substance involved in your mood — is produced in the gut? In this blog, we’ll take you through the remarkable interaction between your brain and your gut.

How your brain and gut work together

Everything that happens in your head is part of the nervous system — and a large part of that system is located in your gut. The nervous system responds, among other things, to stress, tension and (negative) thoughts. Have you ever noticed that when you’re nervous, you need to go to the toilet more quickly? Your gut can tell you a great deal about how you’re doing, both physically and mentally. That’s why it’s often referred to as the second brain. We call this collaboration the ‘gut–brain connection’.

The gut and stress

When you experience stress, the so-called ‘fight or flight’ system is activated, signalling to your brain that it’s time to take action. This triggers certain responses that affect, among other things, your gut, digestion and ultimately your gut microbiome. Stress can cause your body to become more acidic more quickly. During short-term stress, adrenaline is released (in response to the fight-or-flight signal). When you experience long-term stress, cortisol is produced continuously, which over time can lead to free-radical damage. If there is a lot of free-radical damage, you need plenty of antioxidants to help clear it up. Antioxidants are found mainly in fruit and vegetables (such as blueberries).

Because we often don’t get enough antioxidants, waste products can build up. This results in a toxic load, meaning the body’s pH level (acidity) is too high, which can damage the gut microbiome. The gut microbiome consists of both beneficial and less beneficial bacteria. A higher pH level can act as nourishment for the less beneficial bacteria and, among other things, reduces the survival of beneficial bacteria.

When you’re under a lot of stress, you also have a higher energy requirement and your body needs more energy to recover. This increases the risk of deficiencies because your gut may not function as well. The nutrients you consume are absorbed less effectively, which in turn affects your immune system. You may notice you develop more vague complaints, have less energy, or get ill more often.

The gut and hormones

Poor gut function doesn’t only affect your physical health — it can also influence your mental state. Various hormones are produced in the gut. When your gut isn’t working properly, for example due to an imbalanced gut microbiome, it costs a lot of energy. That means there’s less energy available for producing these hormones. There are several types of hormones that are produced or regulated in the gut. Below, we briefly discuss neurotransmitters, HPA-axis hormones and oestrogen.

Neurotransmitters

Neurotransmitters are the body’s ‘messenger chemicals’ and send signals such as when we’re tired or hungry. Dopamine, for example, plays a role in emotional responses and influences memory, concentration and mood. Serotonin affects appetite, emotions and cognitive function, and is the precursor to melatonin, which regulates our sleep–wake cycle. Noradrenaline (or norepinephrine) is responsible for our ‘fight or flight’ system, which is activated when we experience stress. Finally, GABA, which stands for gamma-aminobutyric acid. GABA helps regulate anxiety and arousal and is also involved in contracting and relaxing our muscles.

Oestrogen

Oestrogen is an important female sex hormone and is found in most hormonal contraception. In the body, oestrogen is processed via the oestrobolome. The oestrobolome is a collection of bacteria in our gut that, among other things, are involved in metabolism. These bacteria play a crucial role in maintaining a balanced oestrogen level in the body.

The oestrobolome — a group of gut bacteria — plays an important role in how oestrogen is processed in the body. A healthy balance of these bacteria appears to support a well-regulated hormone balance. In addition, more and more research is being carried out into the relationship between the oestrobolome and processes such as inflammatory responses in the body. Exactly how these mechanisms work is still being actively investigated.

Diet and lifestyle choices play an important role in supporting a healthy oestrobolome. Eating fibre-rich foods, avoiding excessive alcohol intake, reducing stress and maintaining a healthy lifestyle can all help promote a balanced oestrobolome.

HPA-axis hormones

There is two-way communication between the gut and the brain via the HPA-axis system. Stress and emotional states can influence gut function and, conversely, gut problems such as irritable bowel syndrome (IBS) can trigger stress responses in the body.

The HPA-axis system regulates our response to stress. It begins in the hypothalamus in the brain, which produces a hormone called CRH. CRH sends a signal to the pituitary gland, a gland in the brain. The pituitary then releases a hormone called ACTH. ACTH travels to the adrenal glands, where it stimulates the release of cortisol, also known as the stress hormone. If you experience stress for too long or too often, it can cause problems. Understanding the HPA-axis system helps us understand how the body responds to stress and how it can affect our health.

How do you know whether your gut health is in balance?

Good gut health is important for your overall wellbeing. At the same time, it isn’t always easy to assess from the outside, as it can vary from person to person. However, there are signs that are often associated with a well-functioning digestive system:

• You have regular bowel movements that feel comfortable for you
• Going to the toilet happens without much effort
• Your stool has a normal shape and consistency (see the Bristol stool chart)
• After eating, you generally don’t experience prolonged discomfort, such as bloating

It’s worth bearing in mind that these signs can differ from person to person and don’t always say something definitive about your gut health. For example, feeling tired after eating may also be related to the composition of a meal.

Do you regularly experience symptoms such as bloating, abdominal cramps or changes in bowel habits? That may be a sign that your digestion is out of balance. If symptoms persist, it’s always sensible to consult a qualified professional.