You’re not just imagining that “gut feeling” when something just doesn’t feel right. Your gut and your brain are in constant close communication—and the health of one impacts the health of the other. Stress and anxiety can trigger symptoms in the gut, while gastrointestinal (GI) inflammation sends signals to the brain and has been linked to mental illnesses including anxiety and depression.
“There’s a complex interplay between stress hormone levels, bowel function, and sensation of pain,” says David Poppers, MD, PhD, gastroenterologist and clinical associate professor of medicine at NYU Langone Health. “These are topics people often don’t want to talk about, but they’re among the most common reasons people seek care in the ER.”
How stress impacts the gut
The GI system houses the enteric nervous system (ENS), which is a collection of neurons and glial cells that’s sometimes called the “small brain” of the gut. It consists of nerve networks that run from your esophagus to your anus and connect directly into the entire digestive system. “It’s a very complex and only partially understood network,” says Dr. Poppers. The ENS regulates the secretion of a variety of hormones and is involved in the functioning and perception of pain and discomfort in the GI tract.
This “gut-brain axis” is bidirectional, meaning the gut sends signals to the brain and the brain sends signals to the gut. Irritation in the gastrointestinal system sends signals to the brain via the central nervous system (CNS) that triggers mood changes, while mood changes send signals from the brain to the gut. “There’s a tremendous interaction between gut health, stress, and emotional health, and the arrow is bidirectional,” says Dr. Poppers.
When you’re stressed, this gut-brain axis carries high-alert stress signals from the brain to the gut. “There’s a direct correlation on the GI tract as part of visceral response to stress,” says Christine Lee, MD, a gastroenterologist at Cleveland Clinic. Your brain releases the stress hormones corticotropin-releasing factor (CRF), cortisol, adrenalin, and norepinephrine, and the GI tract has loads of receptors for these hormones. “If you’re faced with a very hungry bear, that’s not the time body wants to focus on digesting,” says Dr. Lee. The hormone CRF slows things down in the upper GI tract (resulting in constipation) and speeds things up in the lower GI tract (resulting in diarrhea).
Two other hormones produced by the gut, ghrelin and leptin, are involved in appetite and sensation of fullness. Stress levels can alter the balance in those hormones so you feel hungrier or lose your appetite, explains Dr. Poppers.
The microbiome—a collection of healthy bacteria, viruses and fungi in the body that’s mainly housed in the gut—also plays a role in the stress-gut connection. The microbiome is credited with doing important work such as supporting digestive and immune system health and producing mood-regulating chemicals like serotonin. Some research suggests that stress alters the bacteria in the gut microbiome (and thus impact its proper functioning) although the effects vary greatly between people. “We don’t know specifically what it’s doing and whether those changes are temporary or long-term,” says Dr. Poppers.
Want to know more about gut health? Check out this food-oriented guide from a top dietitian:
Why does stress manifest differently in some people?
We all respond to stress differently, and we all have different GI symptoms, says Dr. Lee. The severity and symptoms are linked to many factors: hormones, receptors, genetics, metabolism, and your microbiome. Even your anatomy—and whether you’ve had abdominal surgery like C- sections or gallbladder surgery—can affect the GI symptoms you experience.
A majority of the body’s serotonin—the “happy hormone”—is made in the gut. “There are more serotonin receptors along GI tract than in the brain,” says Dr. Lee. Serotonin sends signals between the brain and the gut, and controls contractions of the GI tract. When serotonin levels are off, it can cause you not only to feel blue but to have GI symptoms like constipation or discomfort. Some people have a lot more serotonin receptors than others, or their receptors are more sensitive for genetic reasons, says Dr. Lee. Imaging of people with GI disorders like IBS shows their brains react differently to gut symptoms. In some people with IBS, low doses of antidepressants—including SSRIs or SNRIs commonly prescribed for anxiety and depression—have been shown to ease diarrhea, constipation, and stomach pain.
Gut bacteria have been shown to play a role in the production of neurotransmitters like serotonin that regulate mood, memory, and learning; since everyone’s unique gut microbiome is a bit different, a stressed out microbiome can manifest in different ways in different people. Your personal microbiome has to do with many complex factors, including where you were raised and your diet or even if you’ve taken a lot of antibiotics. “It’s like snowflakes: no two are the same, and the bacterial species and content and the types of different bacteria when they are involved in digestion and fermentation of foods can produce different symptoms in different people,” says Dr. Poppers.
Another important factor in the severity of gut symptoms you experience is how you respond and adapt to stress. Do you tend to catastrophize, or see the worst possible outcomes in every situation? Or do you find healthy ways to cope with your stress and look for alternate perspectives? “Being able to accept that I may not like this but this is something I have to deal with…makes a huge difference,” says Karen Conlon, LCSW, a psychotherapist in New York City who specializes treating clients with functional bowel disorders like IBS.
Being solution-oriented and adaptable helps reduce the impact of stress on the gut by helping you to regulate your emotions and control your reactions. “If people don’t have the right tools to do that, it makes it a lot more difficult to get themselves mentally well but also to better their gut health,” says Conlon.
Keep in mind, a few red flag GI symptoms could signal a more serious disorder like Crohn’s or ulcerative colitis, including rectal bleeding, a sudden dramatic consistent change in bowel habits, unintentional weight loss, and sudden dramatic abdominal pain. If you’re experiencing these symptoms, be sure to check in with your doctor ASAP.
What are the long-term impacts of a stressed gut?
Acute stress generally passes. Chronic stress doesn’t, and it can have a great impact on the body in the long term. Chronic stress increases levels of the stress hormone cortisol. Prolonged, elevated levels cortisol can cause anxiety, drain energy, and interfere with the body’s ability to heal. Long-term effects include a shifting in the metabolism to store more belly fat, because it’s easiest to convert into sugar. Long-term exposure to cortisol also decreases the body’s ability to heal, explains Dr. Lee.
“If the gut is always having to deal with these signals from the brain and vice versa that things are not going well, your digestive process is going to be impacted,” says Conlon. Constant high alert signals interfere with the digestive process and may contribute to functional GI disorders like IBS, she adds.
How to manage your stress for a happier gut
Conlon offers the following tips to have a healthier reaction to stress—both for your mind and your gut:
- Adjust your diet. Many doctors recommend probiotics and dietary changes to help improve mood, since there’s a connection with the balance of bacteria in the microbiome and mood. (It’s a huge focus of nutritional psychiatry.) Listen to your body after you eat: if you notice you feel sluggish or your mood changes, you may need to change your diet with the help of a dietitian, if possible. A Mediterranean diet—which features lots of fresh, whole foods like veggies, fruits, fish lean meats, whole grains, nuts, seeds—has been shown to support the microbiome.
- Learn diaphragmatic breathing techniques. Slow, deep breathing activates the parasympathetic nervous system, which reduces your cortisol levels and puts your gut into rest and digest mode. “It can be incredibly helpful to let the brain know that all is well in the body,” says Conlon.
- Practice gratitude on a daily basis. There are days (especially in the past few months) when it can feel like everything’s going wrong. That’s okay—you shouldn’t deny or suppress negative feelings. Instead, try to focus on even the smallest thing that gives you delight that you might have otherwise taken for granted. “It helps to impact your mindset. The research shows it does help with altering your mood in a positive way,” says Conlon.
- Consider talking to a trained mental health professional. If stress or anxiety is really getting to you, talking to a pro can help both your mental and your gut health. Therapy like cognitive behavioral therapy (CBT) teaches people to better manage their response to stress and to handle digestive symptoms. “CBT has been shown to be very effective in some [IBD] patients” to control symptoms like pain and changes in bowel movements, says Dr. Poppers.
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