Advanced Medicine’s Gut-Brain Connection by Dr. Robyn Murphy

Rope tied in knotsUnderstanding how your gut could be affect your brain

There is no doubt that the gut is sensitive to emotion. Many are familiar with “butterflies” in your stomach or loose stool with anxiety. Well research reveals just how the gut-brain connection influences our emotional response.

It makes sense that the brain has direct influence over the gut. The brain is the master control, which sends signals to the digestive tract through our autonomic nervous system to enhance overall function and optimize nutrient breakdown and absorption. This includes the secretion of stomach acid, motility of the gut and blood flow to the digestive tract, controlled by the vagus nerve and glandular/hormonal output.1

During stress these signals get disrupted. The body diverts energy away from digestive function and increases adrenalin, which directs circulation towards the heart and muscles to “fight or flight”. Chronically, this wreaks havoc on your digestion. Many experience heartburn, bloating, gas, reduced appetite, constipation or diarrhea and overall poor digestion, many symptoms that mimic IBS.

In those with IBS, the gut-brain signals become disrupted. Those with diarrhea predominant IBS are shown to have a heightened autonomic and stress response, also known as hyper-responsiveness of the autonomic nervous system.2 Interestingly, those with constipation predominant IBS present with a significantly lower autonomic response of the vagus nerve.3 Stress, anxiety, depression and stressful life events are some of the most significant risk factors for the development of IBS.4 Infection can lead to physical stress on the body. Recent meta-analysis demonstrate a six fold increase in the risk of developing IBS after an intestinal infection, which remains elevated up to two to three years post infection.5,6

The Second Brain

As it turns out, the communication between the gut and the brain is a two way street. The gut, which is also called the second brain, influences the brain’s emotional response, including the release of stress hormones (cortisol and CRH). Research shows that those who suffer from digestive complaints are at a higher risk of mental health complaints, such as depression and anxiety.7

To add another layer to the story, emerging data shows how the gut microbiome affects brain signalling. Changes within the gut bacteria are shown to influence pain perception in those with IBS by influencing inflammation, the stress response, immune function and areas in the brain that process emotions called the amygdala.

Probiotics are now being used to alter psychological stress and improve pain sensitivity in those with IBS. Gut microbes are shown to produce a number of gut hormones, SCFAs, and neurometabolites (GABA, NE, DA), which modulate the function of the nervous system.8,9 These products have such a strong effect on the brain that some studies show the use of certain strains of probiotics to improve mood significantly in those with mild to moderate depression.10

Next Steps


Don’t guess, assess! Find out through objective functional testing to see the underlying mechanism of your symptoms.

  • HRV (heart rate variability) shows the state of the nervous system to assess for heightened autonomic and stress response
  • CDSA stool testing revels the function of your digestive tract and microbial balance
  • Hydrogen breath test (SIBO) testing identifies an overgrowth of bacteria in the small intestine. Found to be positive in up to 87% of those with IBS.

Based on these findings it is imperative that the relationship between the gut and the brain be addressed during treatment. For those who suffer from mental health disorders, improving gut function while reducing autonomic stimulation (the stress response) can be an effective approach to modulating the nervous system to find relief from anxiety, insomnia and depression. In addition, addressing gut concerns can optimize your digestion and absorption of natural health products and foods, which contain essential nutrients to improve your recovery and repair.

On the other end of the spectrum, it is important to address the balance of the nervous system when digestive symptoms are present. Alterations in the autonomic nervous system can not only affect functional gut disturbances, but hormone, immune, cardiovascular, detoxification and reproductive systems as well.11

Could stress be affecting your digestive complaints?

Physical signs of stress12

  • Stiff or tense muscles, especially in the neck and shoulders
  • Headaches
  • Sleep problems
  • Shakiness or tremors
  • Recent loss of interest in sex
  • Weight loss or gain
  • Restlessness

Behavioral symptoms

  • Procrastination
  • Grinding teeth
  • Difficulty completing work assignments
  • Changes in the amount of alcohol or food you consume
  • Taking up smoking, or smoking more than usual
  • Increased desire to be with or withdraw from others
  • Rumination (frequent talking or brooding about stressful situations)

Emotional symptoms

  • Crying
  • Overwhelming sense of tension or pressure
  • Trouble relaxing
  • Nervousness
  • Quick temper
  • Depression
  • Poor concentration
  • Trouble remembering things
  • Loss of sense of humor
  • Indecisiveness

Talk to your healthcare profession to address these concerns and relieve your discomforts.

In best of health,

Dr. Robyn Murphy, ND


  1. Matteoli, G., Gomez-Pinilla, P.J., Nemethova, A., Di Giovangiulio, M., Cailotto, C., van Bree, S.H., Michel, K., Tracey, K.J., Schemann, M., Boesmans, W., et al. (2014). A distinct vagal anti-inflammatory pathway modulates intestinal muscularis resident macrophages independent of the spleen. Gut 63, 938–948.
  2. Punyabati, O., Luikham, L.A., and Singh, M.A. Sympathetic Response in Symptom Subgroups of Irritable Bowel Syndrome (IBS).
  3. Aggarwal, A., Cutts, T.F., Abell, T.L., Cardoso, S., Familoni, B., Bremer, J., and Karas, J. (1994). Predominant symptoms in irritable bowel syndrome correlate with specific autonomic nervous system abnormalities. Gastroenterology 106, 945–950.
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  10. Carabotti, M., Scirocco, A., Severi, C., and Severi, C. (2015). The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Ann. Gastroenterol. 28, 203.
  11. Vighi, G., Marcucci, F., Sensi, L., Di Cara, G., and Frati, F. (2008). Allergy and the gastrointestinal system. Clin. Exp. Immunol. 153, 3–6.
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