stress and digestion

Have you ever heard of the fight-or-flight response? When you experience stress, your body is essentially being “attacked”. As your body prepares to either fight the perceived stressor or flee from it, the sympathetic nervous system becomes activated. What is interesting here, is that your body can’t actually tell the difference between types of stressors1,3. Are you stuck in a bad traffic jam? Are you experiencing relationship issues? Or is it something as drastic as being chased by a lion or bear? The fight-or-flight response is our main survival mechanism, so each time we are faced with any stressor, our body becomes solely concerned with fighting or fleeing from the perceived threat1 (“freezing” has also recently been studied as one of the biological responses to acute stress2).


Cortisol is a glucocorticoid hormone that is secreted by the adrenal glands when the body experiences stress, which is why it is also known as the “stress hormone”. Cortisol secretion is controlled by the hypothalamus, pituitary gland, and the adrenal gland, commonly referred to as the HPA axis. The HPA axis activates the sympathetic nervous system and the stress response. When the hypothalamus releases corticotropin-releasing factor, this hormone binds to receptors on the pituitary gland. This stimulates the release of adrenocorticotropic hormone, which then binds to receptors on the adrenal gland, which ultimately releases cortisol3-4. Excessive levels of cortisol in the body can negatively impact many of the body’s systems and has a significant effect on the digestive system1,3

stress and digestion

During the stress response, cortisol aids in moving blood flow towards the brain, large muscles, and limbs rather than towards the digestive tract. Therefore, our body is not concerned with digestion, and actually suppresses it in this mode. On the other hand, the parasympathetic nervous system stimulates the rest-and-digest response. When the body goes into fight, flight, or freeze mode, digestion essentially shuts down3. This can be a huge issue for someone who is constantly experiencing stress. If the body is constantly in a stressful state and cortisol levels remain extremely elevated, problems with the digestive system may arise3,5.

Stress negatively affects gut motility. In some cases, constipation can occur, meaning the system is unable to rid itself of waste, leading to bloating, gas, and/or stomach pain. It can also lead to development or exacerbation of various gastrointestinal disorders such as IBS, IBD, GERD, and more.

Stress can also cause diarrhea, brought on by food moving too quickly through the digestive system. This results in nutrient malabsorption which can lead to nutrient deficiencies. As mentioned previously, the decrease in overall blood flow during the stress response causes metabolism to slow down. Thus, if you eat while you’re stressed, such as too fast or too much in a given period of time, this reduces your metabolism3,4-5.

Additionally, stress can adversely affect intestinal permeability. Normally, the intestinal epithelial lining functions as a barrier, prohibiting the passage of toxins, antigens, and harmful bacteria from entering through the gut lumen. This blocks pathogens from entering into the bloodstream. In the state of stress, the production of corticotropin-releasing hormone by the hypothalamus directly affects the intestinal lining as it increases permeability. Pathogens are able to move through, leading to a term you may have heard called, “leaky gut”. Leaky gut can consequently result in inflammation and irritation of the mucosal lining1,4-5.

Stress also has a direct effect on the gut microbiome. It causes an imbalance of good and bad bacteria, as much of the good bacteria is wiped out by the sympathetic nervous system. The gut microbiome plays a large role in the immune system. The gut mucosal immune system acts as a protective barrier for the intestinal tract. If there are pathogenic bacteria present in the gut microbiome and/or not as many good bacteria, this leads to immunity dysfunction and the development of disease1,4-5.

Maintaining your digestive health is important as it reduces risk for development of gastrointestinal disorders. Plus, it can improve your immune health as well, since the majority of your immune system is housed in your gut! It’s extremely important to explore stressors, and work to lower your perception of stress, to ultimately keep your digestive system healthy. Taking the time to do this will lead to benefits such as improved digestion and nutrient absorption, as well as reduce your risk for the development of various GI disorders1,3.

If you are concerned about your stress levels and how your health may be impacted by it, schedule an appointment with one of our nutritionists today. 

Written by Leila G., student intern, James Madison University 



  1. Does Stress Cause Digestive Problems? KelseyKinney Website. Accessed October 25, 2018.
  2. Schmidt N, et al. Exploring Human Freeze Response to a Threat Stressor. Journal of Behavior Therapy and Experimental Psychology. 2008;39(3): 292-304.
  3. Cortisol — Its Role in Stress, Inflammation, and Indications for Diet Therapy. Today’s Dietitian. Published November 2009. Accessed October 25, 2018.
  4. Glucocorticoids. Colorado State University Vivo Pathophysiology Web site. Accessed October 20, 2018.
  5. Konturek PC, Brzozowski T, Konturek SJ. Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options. J Physiol Pharmacol. 2011;62(6):591-9.
  6. Huerta-Franco MR, Vargas-Luna M, Tienda P, et al. Effect of occupational stress on the gastrointestinal tract. World J Gastrointest Pathophysiol. 2013;4(4):108-118.