How stress affects digestion and can lead to diarrhoea

One of the first direct observations of the effect of emotions on digestion dates back to the 19th century. In 1833, the American physician William Beaumont described the results of many years of research carried out by Alexis St. Martin, who, following a gunshot wound, was left with a fistula that allowed the functioning of his stomach to be observed. Beaumont noted that strong emotions could alter the secretion of gastric juice and the rate at which the stomach empties, which was one of the earliest pieces of evidence for a link between mental state and the functioning of the gastrointestinal tract.

1. The development of diarrhoea
2. The effect of stress on diarrhoea
3. Managing diarrhoea
4. FAQ – frequently asked questions about stress and diarrhoea

The development of diarrhoea

Diarrhoea occurs when the stool contains too much water, and bowel movements become looser and usually more frequent than normal. This can happen for a number of different reasons. One of the most common is gastrointestinal infection caused by viruses, bacteria or parasites. Some microorganisms damage the intestinal lining, whilst others produce toxins that increase the secretion of water and electrolytes into the intestine.

Diarrhoea can also be linked to diet. If certain nutrients are not properly digested or absorbed, they remain in the gut and trap water there. This mechanism can occur, for example, in cases of lactose intolerance or following the consumption of large amounts of certain polyols. Loose stools may also occur following the consumption of contaminated food, excessive amounts of alcohol, high doses of caffeine, or products to which a person is particularly sensitive.

Diarrhoea is one of the possible side effects of certain antibiotics, magnesium preparations, laxatives and some medicines used to treat chronic conditions. Chronic or recurrent loose stools may also be caused by gastrointestinal disorders or disturbances in gut-brain interactions. The rate at which the bowels function is influenced not only by meals, infections or medicines, but also by the nervous system. One of the factors that can temporarily alter motility and secretion in the gastrointestinal tract is stress.

The effect of stress on individual parts of the gastrointestinal tract

The effect of stress on diarrhoea

Sudden stress triggers a reaction in the body designed to prepare it for rapid action. This alters the functioning of the nervous system and hormone secretion, and the effects can also be felt in the stomach and intestines. In some people, the stomach begins to work more slowly, whilst the intestines work more quickly. Food then moves through the system more efficiently, leaving the body less time to reabsorb water from it. This can lead to a sudden urge to pass stools, more frequent visits to the toilet, and sometimes diarrhoea.

Stress can also make the bowels more sensitive. Their normal movements may then be felt as rumbling, cramps, abdominal pain or a sudden urge to go to the toilet. Such symptoms are more common in people with irritable bowel syndrome.

Chronic stress can disrupt the digestive tract’s rhythm over a prolonged period, affect the amount of fluids secreted and increase the sensitivity of the gut. Its link to the gut microbiota is also being studied, although these relationships are not straightforward. In one person, prolonged tension may be associated with diarrhoea, in another with constipation, and sometimes both problems occur alternately. Stress may therefore be one of the factors exacerbating diarrhoea, but it is not always the main cause.

Managing diarrhoea

Diarrhoea can primarily lead to dehydration and the loss of electrolytes, such as sodium and potassium, which can cause weakness, dizziness, muscle cramps and heart rhythm disturbances. It is particularly dangerous in young children, the elderly and those with chronic illnesses, and when it persists for a long time, is very severe or is accompanied by a fever, blood in the stools or severe abdominal pain.

A light, easily digestible diet consisting of simple meals, combined with adequate fluid intake, is usually effective for diarrhoea. Suitable foods include rice, boiled potatoes, bananas, wheat bread, boiled carrots, light soups and lean meat, provided they are well tolerated.

“Stress isn’t just in your head. The nervous system and the digestive tract are in constant communication, which is why severe stress can, in some people, speed up bowel movements, increase the urge to pass stools and worsen diarrhoea. However, this does not mean that recurring bowel problems should automatically be attributed to stress.” Anna Zięba – Dietitian

FAQ – frequently asked questions about stress and diarrhoea

Can stress really cause diarrhoea?

Yes. Severe stress can affect the nervous system that regulates the digestive tract. In some people, this leads to increased bowel motility, a stronger urge to pass stools and the onset of loose stools. However, the reaction varies from person to person – stress can also cause constipation, nausea or abdominal pain.

Why do I feel the urge to go to the toilet before an important event?

A stressful situation activates the mechanisms responsible for the body’s response to a threat. This also alters the functioning of the digestive tract. The large intestine may begin to contract more intensely, which is why a sudden urge to pass stools may occur before an exam, a public speaking engagement, a competition or an important meeting.

How long can stress-related diarrhoea last?

There is no set duration. In some people, symptoms only occur during periods of intense stress and subside quickly; in others, they recur during periods of chronic stress. However, long-lasting or frequently recurring diarrhoea should not be automatically assumed to be ‘nervous’ in origin, as it may have another cause.

Can stress make irritable bowel syndrome worse?

Yes. Irritable bowel syndrome (IBS) is one of a group of disorders involving the gut-brain axis. In some people, stress and strong emotions can exacerbate abdominal pain, changes in bowel habits, diarrhoea or constipation.

What should you eat when you have stress-induced diarrhoea?

The most important thing is to stay properly hydrated. Meals should be simple and easy to digest. Good choices include rice, boiled potatoes, wheat bread, bananas, cooked carrots, light soups and lean meat. There is no need to go without food, but it is worth temporarily cutting down on foods that personally make your symptoms worse.

Can coffee make diarrhoea worse during times of stress?

It can. In some people, caffeine stimulates bowel activity. If stress is already accompanied by increased gastrointestinal motility, large amounts of coffee or other caffeinated drinks may further increase the urge to pass stools.

Do you need to replenish electrolytes when you have diarrhoea?

With severe diarrhoea, electrolytes – primarily sodium and potassium – are lost along with water. Adequate rehydration is therefore particularly important. In cases of significant fluid loss, oral rehydration solutions with the appropriate composition should be used.

When should diarrhoea not be attributed to stress?

Medical consultation is particularly required in cases of prolonged or recurrent diarrhoea, as well as diarrhoea accompanied by blood in the stools, high fever, severe abdominal pain, marked signs of dehydration, weakness or unintentional weight loss. Stress can exacerbate intestinal complaints, but it should not automatically be considered the cause without taking other possibilities into account.

Sources:

• Tache, Y., Larauche, M., Yuan, P. Q., & Million, M. (2018). Brain and Gut CRF Signaling: Biological Actions and Role in the Gastrointestinal Tract. Current molecular pharmacology, 11(1), 51–71. https://doi.org/10.2174/1874467210666170224095741
• Mönnikes, H., Tebbe, J. J., Hildebrandt, M., Arck, P., Osmanoglou, E., Rose, M., Klapp, B., Wiedenmann, B., & Heymann-Mönnikes, I. (2001). Role of stress in functional gastrointestinal disorders. Evidence for stress-induced alterations in gastrointestinal motility and sensitivity. Digestive diseases (Basel, Switzerland), 19(3), 201–211. https://doi.org/10.1159/000050681
• Chang, Y. M., El-Zaatari, M., & Kao, J. Y. (2014). Does stress induce bowel dysfunction?. Expert review of gastroenterology & hepatology, 8(6), 583–585. https://doi.org/10.1586/17474124.2014.911659