You’re always on the go, always jumping up to do the next thing. Work, email, picking up the kids, grocery shopping, cooking, organising a birthday gift, taking the kids to extracurricular activities, remembering appointments, more work. You feel frazzled.

And although you’ve not had time to go to the doctor, you suspect you have irritable bowel syndrome (IBS). All the signs are there – bloating, stomach pain, the inconvenience of needing to run to the loo. As if you need anything more going on in your life!

You’re stressed. I get it. But what if your stress and your tummy ache were connected? And if you could make some simple lifestyle changes to ease both your IBS symptoms and your feelings of stress, wouldn’t you go for it? It all starts with your gut-brain axis.

How Does the Gut Brain Axis Work?

Cast your mind back to learning about biology at school. You likely learned about the different systems of the body – the skeleton, the cardiovascular system, digestive system, nervous system, and so on. But your body is more remarkable than you might realise – instead of it being made up of different systems that occasionally interact, the reality is that everything is working together. Your gut and brain have a particularly close relationship: one of the reasons your gut instinct is so powerful!

Let’s face it, you only really think about your gut when something’s wrong – you’re constipated, or you keep running to the loo. But it’s a highly-developed organ that handles more than just digestion. Your large colon is host to a huge colony of bacteria, called your gut microbiome [1]. And your gut has neural tissue embedded in the walls – and makes up to 95% of your serotonin, a neurotransmitter that promotes feelings of wellbeing and happiness [2]!!

Your gut-brain axis is an information highway, sensitive to small changes. It’s made up of:

  • Hormone communication: Your gut microbiome likes to tell you what’s up through either producing hormones, or triggering their release [3]. They can even interfere with your serotonin levels – or influence your food cravings [4]!
  • The vagus nerve: This is actually the longest cranial nerve in your body! It leads from your brain all the way down to your gut. While it passes movement and sensory information, and triggers the movement of your gut muscles to aid digestion, it also controls your heartbeat [5]. While your brain uses the vagus nerve to control digestion, your gut also uses it to send information back – amazing. The brainstem of the vagus nerve links up with your hypothalamus and limbic system – both of which have a hand in the regulation of your emotions.

Think of your brain and gut as having a close parent-child relationship. The brain is the parent, and thinks it’s in control – but the gut, as the child, is able to influence the brain in subtle (and not so subtle) ways! When the relationship runs smoothly, all is well. But if something is wrong with the child, it obviously affects the parent – and vice versa. It’s the same with the gut and brain. And when you’re stressed, your gut alters its behaviour accordingly.

What Does Stress Do to My Digestion?

At one time or another you’ve felt butterflies in your tummy while nervous, or felt nauseous when receiving bad news. It’s clear that your gut speaks louder than words at times. Stress doesn’t stop at the brain – unfortunately, it’s a whole-body experience! And you can thank your ancestors for that. When you sense danger, your hypothalamic-pituitary-adrenal-gonadal (HPA-G) axis kicks in, alongside your fight-or-flight response [6].

General symptoms of stress in the body include:

  • Headaches
  • Difficulty thinking
  • Fatigue
  • Increased heart rate
  • Tense muscles
  • Inability to relax or sleep
  • Low libido

Long term effects of stress on the digestive system include:

  • Nausea
  • Diarrhoea
  • Constipation
  • Abdominal pain
  • Indigestion
  • Loss of appetite
  • Bloating

In fight-or-flight, your body is primed to take sudden action – instructing your adrenal glands to release adrenaline and noradrenaline [7]. These hormones keep your heart racing, and your muscles ready to either take a stand – or run away! But adrenaline also reduces the blood flow to your gut, slowing your digestion right down. It makes sense in the moment – when responding to danger, your body needs to stop spending energy on certain functions so that it can funnel energy and blood flow to critical areas; for example, the muscles in your legs to help you move faster if you need to get away. Meanwhile, your HPA axis triggers the release of the hormone cortisol [8].

Cortisol is a clever hormone with a wide variety of functions, but it’s your main stress hormone, and it keeps you super alert in times of danger [9]. In fact, your adrenal glands release it every morning to help you wake from sleep. Cortisol also puts non-essential processes on hold, including your immune system, reproductive system – and yes, your digestion.

While our ancestors were able to use this stress response to survive, the trouble nowadays is that our brains can’t differentiate between life-threatening situations and the stresses of modern life! It’s not your fault that an email from your boss after 6pm, a screaming child, or a traffic jam gives you a pounding headache or stomach pain – it’s the way that you’re wired. However, if your stress response is triggered over and over, it can lead to chronic stress, which in turn can cause a number of diseases [10,11].

Chronic stress can lead to the development of irritable bowel syndrome or increased leaky gut (intestinal hyperpermeability), and even cause a vicious cycle of stress, anxiety, and depression through the gut-brain connection [12,13].

How Does Stress Affect the Gut Microbiome?

Your gut microbiome is a big deal – your relationship with the bacteria in your large intestine is highly beneficial. While you provide the bacteria with a home, perfect conditions to thrive, and food, they’re not squatters – they pay their way!

The colony in your gut provides you with:

  • Nutrients – including important branched-chain amino acids which they create out of fibre, which you can’t make alone. These amino acids are crucial for healthy metabolism and muscle function.
  • Protection from other microorganisms.
  • Maintenance of your intestinal barrier.
  • Reinforced immune system response through communication.
  • Regulation of your cognition and mood. (More on this later!)

Not bad for a bundle of microscopic creatures!

Because of this symbiosis, your gut microbiome is sensitive to change – whether it’s a change in diet, infections, medications, exercise levels, introduction of probiotics, or stress [14]. These factors can cause dysbiosis – an imbalance in the gut microbiome, where the harmful bacteria outnumber the helpful strains. And in the case of stress, communication between your brain and gut can lead to changes such as:

  1. A reduction in mucus production – that can affect the colony, leading to inflammation in the gut lining [15].
  2. A change in oxygen levels in the gut – because your stress response has slowed down your digestion and reduced the blood flow to the area, the change in oxygen levels in the gut can also impact your microbiome [16].
  3. Reduction in the number of immune cells available in your gut – when cortisol triggers the temporary suppression of your immune system, it has a detrimental effect on your microbiome [17].
  4. A dysregulated circadian rhythm causing changes in your gut microbiome – stress-induced insomnia or poor sleep can also affect the health of your microbiome as the bacteria rely on a well-regulated circadian rhythm [18].

Stress has a bad effect on your gut microbiome and the health of your gut. But are there times where the gut can have an effect on your stress levels or mood, through the gut-brain axis?

So Can Your Gut Affect Your Mood?

Your vagus nerve transmits information back up to your brain from your gut [19]. While scientists have yet to work out the exact mechanism, your gut and microbiome can indeed incite stress [20]. Depression is common in patients suffering from irritable bowel syndrome (IBS) [21]. Your body craves balance or homeostasis: when something is up with your gut, it makes sense that there would be a direct affect on your brain.

Your gut can trigger the following mechanisms:

  • Low grade inflammation in the brain, which has been linked with depression in some patients [22,23].
  • Pro-inflammatory cytokines also triggering the HPA-G axis to go off over and over [24]. This results in your stress feeding off itself in a vicious circle – and results in poor sleep [25].
  • A dysregulated stress response – heightening feelings of anxiety. Usually your gut microbiome can regulate your stress response creating a closed loop that promotes balance [26]. Removal or damage of the microbiome in animal studies indicate that when the microbiome is faulty, this natural check on stress levels is taken away – creating a feedback loop of stress and anxiety [26].

Remember, these are only the mechanisms we know of at the moment. The brain-gut axis is a hot topic to study, so I expect more discoveries may be made that connect the working of the gut to feelings of stress.

So stress is a big deal health-wise, and it’s time to consider the ways in which to combat it.

What Can You Do to Destress Yourself?

There’s nothing more infuriating than to be told “Don’t stress!” Because as you now know, it’s not as simple as flicking a switch – there’s a number of complicated processes going on in your gut, brain, and indeed the rest of your body. But there are practices you can put in place to reduce the amount of stress you’re under – without quitting your job and running away to a tropical island, as tempting as it may be!

Here are four science-backed stress busters:

  • Shake that behind! Or go for a walk, swim, jump on a trampoline or a rebounder, or practice yoga if dancing is not your thing! The important thing is that you move. Exercising triggers production of serotonin and helps your HPA axis to self-regulate [27,28]. Exercise can also alleviate common digestion issues such as constipation and slow digestion – so give it a go!
  • Sort your sleep out! Sleep is the bedrock of your mental health and cognitive function – your brain can only run certain maintenance tasks when it’s asleep, such as clearing out debris through the glymphatic system [29,30]. Although high levels of cortisol can hinder getting sleep at first, it’s important to set good habits – such as no phones or screens in the bedroom, going to bed at the same time every night and having some quiet time – those work emails can wait.
  • Look up from your screen! Now, I love my smart phone as much as the next person, but I do try to limit how long I spend on it. Not only is it a time-suck, but if you’re already stressed it can make you feel worse – constantly checking your phone or Facebook use can slow your stress recovery [31]. Why not make arrangements to meet up with a friend or do some volunteer work? If you don’t have any social support to rely on, it’ can be much harder to recover from stress [32].
  • Meditate – This is my favourite stress buster! Though it may seem a little woo-woo to you, there are some solid scientific studies showing the benefits of meditation for the stressed. It helps thicken your prefrontal cortex, responsible for processing your emotions and regulates your stress response, healing your microbiome [33,34].

Another major way you can regulate your stress response is through the right food and nutrition. After all, if the gut-brain axis is so important, you need to feed it the right things.

What Foods Reduce Stress Hormones?

Foods to reduce stress

The most powerful influence on your gut microbiome is diet [35]. The food you eat can also affect inflammation in your gut, intestinal hyperpermeability, and your mood [36,37,38]. I’m not going to lecture you – you know what foods are bad for you, though I would always recommend checking with a functional medicine practitioner, nutritionist or health coach for individualised support. Instead, I’d like to concentrate on foods that help heal the gut and mind.

Try these foods to aid you in your journey of better stress management:

  • Fruit and vegetables high in fibre: be wary of fruit that contains a lot of sugar, such as bananas, as sugar is inflammatory, although added sugars are the biggest culprits. However, fibre is absolutely essential to gut health, as your microbiome thrives on it [39]. Complex carbohydrates can also promote serotonin production in the brain [40].
  • Fermented foods such as live cultured yogurt, kombucha, and kimchi: these are natural probiotics, suitable for improving the health of your gut microbiome [41]. Do introduce them into your diet gradually, otherwise you may experience gas.
  • Fish, nuts, and seeds high in Omega-3 Fatty Acids: not all fats are bad, and these healthy fats can reduce the impact of stress hormones [42].
  • Dark chocolate: yes, I’m saying you can have chocolate! Dark chocolate can improve your mood and reduce stress – in moderation [43].

I believe that everyone is an individual, and as such, there is no one diet that caters for all. Life would be boring if we were all the same, but sometimes it can be difficult to know if you’re doing the right thing by your body. Especially when you’re dealing with embarrassing gut issues, or are under a lot of stress. If you’re unsure what to do, I’d recommend working with a functional medicine practitioner, nutritionist or health coach – or someone who practises all three, such as myself! You don’t have to shoulder your stress alone.

If you’re struggling with a stress problem or digestive issue and need a functional medicine practitioner, nutritionist or health coach in the Preston or Blackburn area, please fill out my contact form or email me directly at – I’m here to help!


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