Introduction to the Gut-Brain Connection

Common Mental Health Issues

Mental health issues are increasingly common worldwide. Mental health issues can range from mild to moderate or severe and can be debilitating for some. A diagnosis isn’t necessarily lifelong, and diagnosis can also change throughout your lifetime.1 

Many mental health issues impact the population. 1 in 4 people in the UK will experience mental health issues yearly.1

The most common mental health conditions are:1,2


Those with depression describe feeling 'low' and losing pleasure in things they once enjoyed.

Symptoms such as irritability, tiredness, loss of appetite or increase in appetite, memory issues, trouble sleeping, and lack of concentration come hand in hand with depression. 8 in 100 people will be diagnosed with depression in any given week.

Anxiety Disorder

Those with an anxiety disorder will have extreme worries that are out of proportion regarding the particular situation. They will have difficulty regulating their fears. They can also feel irritable, restless, tired, tense and have trouble sleeping. 6 in 100 people will be diagnosed with anxiety disorder in any given week.

Panic Disorder

Panic disorder involves having unexpected and recurring panic attacks. The thought of having another panic attack can cause them anxiety.

Panic attacks can include increased heart rate, sweating, shaking, lack of concentration and fear. Less than 1 in 100 people will be diagnosed with panic disorder in any given week. 

Obsessive-Compulsive Disorder (OCD)

OCD sufferers may have thoughts, images or pulses that recur and are hard to eliminate. These are referred to as obsessions. They may feel a strong urge to carry out specific physical acts or mental processes, known as a compulsion.

1 in 100 people will be diagnosed with OCD in any given week.

Post-Traumatic Stress Disorder (PTSD)

PTSD often occurs after a particularly stressful or traumatic event. The symptoms of PTSD often include repeated and intrusive memories of the possibility that sufferers find distressing.

Physical symptoms such as shaking and sweating can accompany the mental processes. 4 in 100 people will be diagnosed with PTSD in any given week.

The Gut-Brain Connection

Our gut health is integral to how our brain works; this is called the gut-brain axis. The brain and gut communicate bidirectionally, sending signals between the central and enteric nervous systems.3

The gut-brain axis is involved in many physiological processes in the body. This includes:4

  • Satiety 
  • Food intake
  • Regulation of glucose and fat metabolism
  • Insulin secretion 
  • Sensitivity and bone metabolism

The gut-brain connection tells us if we’re hungry or stressed or ingested a disease-causing microbe. You know when you eat something and begin to feel unwell? Perhaps you get sweaty, feel sick or have an urgent need to run to the loo? That’s your gut providing feedback through chemicals and hormones to your brain to let you know what’s happening.

The skewed physical and chemical connection between the gut and brain can lead to emotional and cognitive issues. This suggests that some mental health conditions can be caused or worsened by gut issues. 

Additionally, 95% of serotonin is made in the gut, so if the gut is unhealthy, the production of serotonin is limited. This can lead to depression, anxiety and other mental health issues.

Serotonin is our “happy hormone” and plays a key role in body functions such as mood, sleep, nausea and sexual desire, which can all impact our mental health. 

Final Thoughts

There is much to learn about the relationship between guts and mental health.

Mental health is an absolute epidemic across the UK, if not the world, and understanding our gut's role in this can help us to make better choices that may alleviate symptoms.

Related content: Introduction to Gut Health and Sleep

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