Stress doesn't just affect the brain – the stomach reacts too. During prolonged stress, the normal function of the intestines can change, which can lead to symptoms such as abdominal pain, bloating, diarrhea, constipation, and acid reflux. In this article, we explain why stress affects the stomach, what role the vagus nerve plays, and what you can do yourself to support both the nervous system and the gut.
Stress doesn’t just affect the brain – the stomach reacts too. During prolonged stress, the normal function of the intestines can change, which can lead to symptoms such as abdominal pain, bloating, diarrhea, constipation, and acid reflux. In this article, we explain why stress affects the stomach, what role the vagus nerve plays, and what you can do yourself to support both the nervous system and the gut.
The Most Important Points
- Prolonged stress can affect both the nervous system and digestion.
- Stress can inhibit the vagus nerve, which is important for normal bowel function.
- Impaired intestinal motility can increase the risk of SIBO in some people.
- Stress stomach can cause symptoms such as abdominal pain, bloating, diarrhea, and constipation.
- Stress management, diet, and good mealtime routines can contribute to a calmer stomach.
What is stress-related stomach discomfort?
There are several factors that can contribute to stomach problems caused by stress, and it is primarily long-term stress that can lead to digestive symptoms.
To understand how stress affects the stomach, we first need to look at how the body responds to stress. Let’s go through what happens during a prolonged period of stress that can cause stomach discomfort.
Stress activates the so-called sympathetic nervous system, which affects the body in several ways. Blood pressure and heart rate increase, blood is directed towards the muscles in the arms and legs, and the stress hormone cortisol is released from the adrenal glands.
In this way, the body can quickly mobilize energy to handle a temporary dangerous or challenging situation. However, when stress becomes prolonged, increased levels of cortisol can negatively affect our health.
When stress is constant (chronic), for example if you work in a stressful environment, have difficulties in family life, experience a stressful school situation, or have an uncertain and challenging everyday life, it can affect your overall health.
How does stress affect the stomach?
The gut and the brain communicate continuously through the nervous system, hormones, and the immune system.
During stress, the body may prioritize other functions over digestion. This can affect:
- Gut movement
- Sensitivity in the gastrointestinal tract
- The experience of pain and discomfort
- The balance of the gut environment
This is why some people notice that their stomach reacts during periods of high workload, worry, or lack of sleep.
What symptoms can stress-related stomach problems cause?
The following symptoms are common in connection with chronic stress:
- Abdominal pain
- Bloating or a gurgling stomach
- Gas
- Diarrhea
- Constipation
- Acid reflux
- Nausea
- Feeling full quickly
How does stress affect the vagus nerve and the stomach?
Stress can affect communication between the brain and the gut through the autonomic nervous system. An important part of this communication is the vagus nerve, which plays a central role in the body’s calming and recovery system — the parasympathetic nervous system.
When the body is exposed to stress, the sympathetic nervous system is often activated, also known as the body’s “fight-or-flight system”. The focus shifts towards functions that help us handle a stressful situation, while processes such as digestion and recovery may be given lower priority.
This can affect how the stomach functions and contribute to common stress-related digestive symptoms such as bloating, changes in bowel movements, and abdominal discomfort.
What happens to the vagus nerve during stress?
The vagus nerve is one of the body’s longest nerves and acts as an important communication pathway between the brain and several organs in the body, including the gastrointestinal tract.
When the parasympathetic nervous system is active — for example, when we rest, breathe calmly, meditate, walk, or practice yoga — the active vagus nerve helps create conditions that support recovery and digestion.
A well-functioning vagus nerve enables communication between the brain and the gastrointestinal tract, and vice versa, through what is known as the gut-brain axis.
During prolonged stress, activity in the parasympathetic nervous system may decrease, which can affect several functions in the body, including the function of the stomach and intestines.
How does reduced vagus nerve activity affect the gut?
The vagus nerve helps regulate, among other things:
- Gut movement (motility)
- Activation of the important valve between the large intestine and small intestine, which helps prevent bacteria from the large intestine from entering the small intestine
- Communication between the brain and the gastrointestinal system
- The body’s recovery processes
When vagus nerve function is reduced (for example, due to stress and an overactive sympathetic nervous system), some people may experience changes in their digestive function.
Examples of symptoms that may occur include:
- Changes in intestinal motility, such as slower intestinal transit and constipation
- Bloating and abdominal pain
- Changes in bowel habits
- Nausea
- Reduced appetite or feeling full quickly
- Acid reflux
Is there a connection between stress, the vagus nerve, and SIBO?
Research shows that intestinal movement plays an important role in maintaining the balance of bacteria in different parts of the gastrointestinal tract.
The small intestine normally contains significantly fewer bacteria than the large intestine. If normal intestinal movement patterns and the activity of the valve between the large intestine and small intestine are reduced, the environment in the small intestine may change. This can contribute to increased bacterial growth in the small intestine, known as SIBO (Small Intestinal Bacterial Overgrowth).
Unlike the large intestine, which has two strong mucus layers that help prevent bacteria from affecting the cells of the intestinal lining, the small intestine has a thinner and more temporary mucus layer. In other words, the small intestine is not designed to contain large amounts of bacteria.
It is often stated that the small intestine contains approximately 100 million times fewer bacteria than the large intestine.
SIBO may be associated with symptoms such as:
- Bloating
- Gas formation
- Digestive discomfort after meals
- Abdominal pain
- Changes in bowel habits
- Acid reflux
- Reduced appetite or feeling full quickly
- Inflammatory conditions affecting the skin (such as rosacea, a butterfly-shaped facial rash), as well as inflammation-related symptoms in muscles, joints, and the nervous system
SIBO is a complex condition where several factors may play a role. In addition to slower intestinal movement, factors such as previous intestinal infections (for example, traveller’s diarrhea), medications that reduce stomach acid over a long period, dietary habits, and alcohol consumption may contribute.
How can you support the vagus nerve and the body’s recovery?
Since the vagus nerve is connected to the body’s recovery system, calm and regular habits may help the body shift from stress towards rest.
Examples of habits that may support vagus nerve activity include:
- Deep and calm breathing
- Moderate physical activity, such as walking
- Sufficient sleep
- Reducing stress around meals
- Time for recovery and relaxation
- Intermittent fasting (for example, skipping breakfast; however, drinking coffee, tea, juice, and similar beverages is still possible)
Would you like to learn more about how you can support your vagus nerve? Read our article “How to Support Your Vagus Nerve”, where we go through practical methods such as breathing techniques, lifestyle habits, and other ways to promote a balanced nervous system.
How can you get rid of stress-related stomach problems?
There are several reasons why stress can contribute to stomach pain and health issues. One possible factor can be SIBO (Small Intestinal Bacterial Overgrowth).
If you have SIBO, increasing your intake of dietary fiber, polyphenols, or other prebiotic products may, in some cases, provide more nutrients for bacteria in the small intestine. This can lead to increased production of by-products from bacterial growth and potentially worsen digestive symptoms.
Some approaches that may help with stress-related stomach problems include:
- Supporting your gut balance with GutClear® (for SIBO, prescription antibiotics may also be used after evaluation by a healthcare professional with knowledge of SIBO).
- Following a Low-FODMAP diet, which may help by reducing the intake of certain carbohydrates that bacteria can use as a food source, potentially reducing gas production and other bacterial by-products.
- Practicing mindfulness.
- Engaging in moderate physical activity (slow jogging, walking, swimming, cycling, etc.).
- Practicing deep breathing exercises regularly throughout the day.
- Avoiding eating between meals and allowing the small intestine time to empty its contents.
- Intermittent fasting may increase vagus nerve activity.
What foods are good for stress-related stomach problems?
In addition to reducing stress in everyday life, there are also dietary approaches that may help ease symptoms related to stress-related stomach problems.
The diet that works best varies from person to person, but some foods and dietary approaches may be gentler on the digestive system.
Can probiotics help with stress-related stomach problems?
Fermented pasteurized sauerkraut juice (for example, from Biotta or Voelkel) may support the gastrointestinal system without adding additional bacteria. This may be especially relevant in cases of SIBO, where there is already an increased amount of bacteria in the small intestine.
What is a Low-FODMAP diet?
A Low-FODMAP diet is a dietary approach where certain carbohydrates that may be difficult for the digestive system to break down are limited.
These carbohydrates can cause gas, bloating, and abdominal pain in people with IBS and other digestive problems.
Which foods are included in a Low-FODMAP diet?
Examples of foods that are often included in a Low-FODMAP diet:
Category | Foods |
Vegetables | Carrots, cucumber, tomatoes, spinach, lettuce, bell peppers, zucchini |
Fruits and berries | Strawberries, blueberries, kiwi, cantaloupe (large portions of apples, pears, and cherries may need to be avoided) |
Grains | Rice, corn, quinoa |
Dairy products | Lactose-free milk, hard cheeses |
Protein sources | Meat, fish, eggs, tofu |
Nuts and seeds | Almonds, walnuts, pumpkin seeds (small portions of certain nuts and seeds may work for some people) |
Sweeteners | Stevia, sucrose, aspartame |
