Stress can cause gastrointestinal problems through the connections between the brain, endocrine system and the gut. Not only can stress make you poop more frequently, it can also cause symptoms like cramping, bloating, flatulence, appetite changes, diarrhoea or constipation. In addition, significant or ongoing trauma has been linked to the onset and exacerbation of many gastrointestinal conditions including: irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), gastroesophageal reflux disease and peptic ulcer disease1.

What happens to your body when you're stressed?

Stress affects all parts of the body, including the gut. In times of stress, the nervous system triggers a release of chemicals and hormones that create a “fight or flight” response – which is designed to make you alert, ready to face the threat or run to safety. Stress causes physiological changes designed to wake the body up and get it moving. This includes higher blood pressure, faster breathing and heart rate, and increased muscle tension. This stress response redirects blood away from the inner gastrointestinal organs in order to supply the limbs with oxygen and nutrients – the stuff needed to make muscles ready to fight, or to run away fast. This slows down the function of the stomach and intestines – and it gets worse. The hormones that the body releases to deal with stress can wreak havoc on the digestive system.

The brain secretes a hormone called CRH (corticotropin-releasing hormone) to stimulate the adrenal glands, which in turn release adrenaline, cortisol, known as the “stress hormone” and other hormones to deal with stress. CRH switches off digestion and suppresses appetite – but the adrenal hormones can cause hunger. These mixed messages cause a stop-start signal in the gut, resulting in symptoms of constipation or diarrhoea.

Stress Ball

The brain and the gut are intimately linked:

  1. The gut and brain talk to each other using nerve fibres, the immune system and endocrine pathways. Signals from the brain can influence gut motility and conversely, visceral messages from the gut can affect brain function and our behaviour.
  2. Central to the communication of the gut and the brain is the gut microbiota. We live in a symbiotic relationship with these microbes: we provide them with nutrients from food we consume, and in return they help us in many ways, including supporting brain development and brain function.
  3. The vagus nerve is a key player in gut-brain communication. About 90% of vagus nerve fibres connect the gut to the brain, whereas only 10% of vagus nerve fibres come from the brain to the gut. So it’s mostly the gut talking to the brain! And it helps the brain make decisions, i.e. when you have a gut feeling about something.
  4. Gut bacteria produce molecules which not only affect how our digestive system works but also influence the brain. For example, certain Lactobacillus and Bifidobacterium produce gamma-aminobutyric acid (GABA), which controls feelings of fear and anxiety and keeps a “busy mind” under control2. Some gut bacteria also aid their host in production of serotonin (which affects the brain to generate feelings of happiness and controls your internal body clock)2.
  5. The gut and its microbial profile influence how much inflammation occurs throughout the body and the brain. Stress signals disrupt the health of these microbes, leading to inflammation, immune problems and GI problems3.

Diet is one of the most important modifying factors of microbiota-gut-brain communication. For example, the behavioural and neurobiological disturbances in stressed mice can be reversed by probiotic bacteria or prebiotic-rich diets. There have also been human trials showing that prebiotic intake reduces one’s tendency to pay attention to negative information, which demonstrates that by taking care of our gut microbiota, we can impact our mood4.

Can stress cause bowel problems?

Stress is often a major underlying cause behind bowel problems such as diarrhoea, constipation and bloating. However, it's also a risk factor for the onset and exacerbation of serious bowel conditions such as IBS and inflammatory bowel diseases (IBD) Crohn's disease and ulcerative colitis. Further up the gastrointestinal tract, stress also contributes to gastroesophageal reflux disease and peptic ulcers. Researchers believe this is because of the link between stress, inflammation, and immune dysfunction.

Studies have shown that stress also directly alters the types of bacteria found in the gut microbiome5. Bacteria in the gut can be loosely grouped as “beneficial” or “harmful”. They all influence the immune system and levels of inflammation locally in the gut and throughout the body. By disrupting the balance of beneficial to harmful bacteria in the gut, stress also causes an increase of inflammation and even tissue damage throughout the gastrointestinal tract6.


“The gut-brain connection works in both directions.  Stress signals from the brain can cause gastrointestinal problems. Likewise, any discord in the gut – particularly in the balance of beneficial to harmful bacteria – can further exacerbate stress. The best health outcomes occur when taking good care of your gastrointestinal health and by using other methods to simultaneously reduce stress.” - Dr Paul Vandewalle.

How to deal with butterflies in your stomach

If stress is contributing to your gastrointestinal issues, try these natural therapies:

  1. Meditation and deep breathing exercises can relax the nervous system and may even relieve gut symptoms. Meditation isn't just effective for dealing with the psychological aspects of stress – it also has a direct impact on gut bacteria and can help to relieve symptoms of cramping, bloating and constipation7.
  2. Studies show that having a regular yoga practice (in combination with meditation) can reduce inflammation in the gut, boost the immune system, and improve symptoms of IBS8,9.
  3. Herbal teas like chamomile, passionflower and valerian have been traditionally used to treat both gastrointestinal complaints and stress. They have been shown to contain chemicals that soothe nervous system signals and reduce the impact of stress hormones on gut tissues10.
  4. Eating a diet rich in polyphenols (which can be found in cocoa, green tea or coffee), fermented foods (e.g. yoghurt, sauerkraut, kimchi or kefir), omega-3 fatty acids (e.g. salmon) and prebiotics (fibre) can help you maintain or improve your gut microbiota composition which could help you take control of your mood and wellbeing.

The connection between the gut and brain is direct, and signals of stress go both ways. Not only can stress make you poop more, but it can contribute to other gastrointestinal symptoms and serious long-term health conditions. Taking care of your emotional and mental health can have a huge impact on your gastrointestinal health, and vice-versa. Speak to your GP or healthcare practitioner if you are concerned about your health.

  1. Mayer, EA. The neurobiology of stress and gastrointestinal disease. Gut 2000;47;861-869.
  2. Pokusaeva, K., et al. (2017) GABA‐producing Bifidobacterium dentium modulates visceral sensitivity in the intestine. Neurogastroenterol Motil., 29:1, e12904.
  3. Gao, X., et al. (2018) Chronic stress promotes colitis by disturbing the gut microbiota and triggering immune system response. PNAS.
  4. Galley, J. D., Bailey, M. T. (2014) Impact of stressor exposure on the interplay between commensal microbiota and host inflammation. Gut Microbes, 5:3, 390 – 396.
  5. Gao, X., et al. (2018) Chronic stress promotes colitis by disturbing the gut microbiota and triggering immune system response. PNAS.,  
  6. Schmidt K, Cowen PJ, Harmer CJ, Tzortzis G, Errington S, Burnet PW. 2015. Prebiotic intake reduces the waking cortisol response and alters emotional bias in healthy volunteers. Psychopharmacology (Berl). 232(10):1793-801.
  7. Househam, A. M., et al. (2017) The Effects of Stress and Meditation on the Immune System, Human Microbiota, and Epigenetics. Adv Mind Bod Med., 31:4, 10 – 25.
  8. Cahn, B. R., et al. (2017) Yoga, Meditation and Mind-Body Health: Increased BDNF, Cortisol Awakening Response, and Altered Inflammatory Marker Expression after a 3-Month Yoga and Meditation Retreat. Front Hum Neurosci., 11, 315.
  9. Kavuri, V., et al. (2015) Irritable Bowel Syndrome: Yoga as Remedial Therapy. Evid Based Complement Alternat Med., 2015.
  10. Srivastava, J. K., et al.  (2010) Chamomile: A herbal medicine of the past with bright future. Mol Med Report., 3:6, 895 – 901.

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