AT A GLANCE: Here are the key things you will learn about improving gut health from three gastroenterologists in this article:
- Fruits, vegetables, whole grains, beans and fermented foods support a healthy gut microbiome.
- Regular, comfortable bowel movements and minimal bloating, abdominal pain or digestive discomfort suggest your digestive system is functioning well.
- Stress, poor sleep and mental health conditions can affect digestion, while ongoing digestive problems can worsen stress and anxiety.
- Probiotics may help certain digestive symptoms, but benefits vary.
- Seek medical attention for persistent changes in bowel habits, abdominal pain, blood in your stool, unexplained weight loss or ongoing diarrhea or constipation.
Gut health refers to the well-being of the digestive system, which is responsible for breaking down food, absorbing nutrients and eliminating waste from the body. It is home to trillions of microorganisms—including bacteria, viruses and fungi—that are collectively known as the gut microbiome.
A healthy gut is essential for overall health and well-being, establishing proper digestion, metabolism and immunity. Meanwhile, poor gut health has been linked to a range of health conditions, such as inflammatory bowel disease, irritable bowel syndrome, allergies and mental health disorders. But understanding how to maintain a healthy gut can set patients’ digestive health on the right track.
The AMA’s What Doctors Want Patient to Know™ series gives physicians a platform to share what they want patients to understand about today’s health care headlines.
In this installment, three physicians took the time to discuss tips and advice for improving your gut health. They are:
- Joanna K. Law, MD, a gastroenterologist who practices at Confluence Health in Wenatchee, Washington.
- Sowmya Palam, MD, a gastroenterologist who also practices at Confluence Health in Wenatchee, Washington.
- March Seabrook, MD, a gastroenterologist in private practice in West Columbia, South Carolina, and delegate in the AMA House of Delegates for the American College of Gastroenterology.
Confluence Health is part of the AMA Health System Member Program, which provides enterprise solutions to equip leadership, physicians and care teams with resources to help drive the future of medicine.
There is no single definition for “healthy gut”
“There is no single agreed definition for ‘healthy gut,’” said Dr. Law.
“Generally, it is described as a state in which the digestive tract and its microbiome can perform essential functions such as digestion, absorption of nutrients, protect against bad microorganisms—such as bacteria and viruses—toxins and inflammatory molecules, and communicate back and forth with the brain and rest of the body through hormones and nerves without disease or bothersome symptoms,” said Dr. Palam.
This “is generally supported by diverse, stable and resilient microorganisms in the gastrointestinal tract,” Dr. Law added.
These signs point to a healthy gut microbiome
There are “signs that suggest that the digestive system and gut microbiome are functioning well,” said Dr. Palam. For example, for “normal, comfortable bowel habits, we use Bristol stool form scale to evaluate this with types 3, 4 and 5 regarded as suggestive of normal colonic transit.
“Types 1 and 2, which are defined as hard and lumpy stools, suggest constipation or slow colonic transit,” she added. “And type 2, 6 and 7, which are defined as loose and watery, suggest diarrhea or rapid transit.”
“It can be normal to have hard or loose stools occasionally depending on diet, stress or medications,” said Dr. Palam. “However, if occurring frequently, it warrants additional evaluation and management.”
A healthy gut microbiome also means there is an “absence of bothersome symptoms,” Dr. Law noted. This includes “minimal bloating, flatulence, rumbling or gurgling, abdominal pain, altered bowel habits, regurgitation—swallowed food coming back into the esophagus and into the mouth—and vomiting.”
Lastly, a healthy gut should also mean you have “effective digestion and nutrient absorption,” Dr. Palam said. This means you are “able to eat a meal without having any significant post-prandial discomfort or sensations.”
Keep an eye out for symptoms
“Many digestive symptoms can be managed with lifestyle changes or over-the-counter treatments, but some symptoms should prompt a conversation with a physician rather than self-treatment,” said Dr. Law. “In general, patients should seek medical advice if they develop a new or persistent change in bowel habits, especially if symptoms last more than a few weeks or represent a significant change from their usual pattern.”
“Symptoms that deserve medical attention include rectal bleeding, black or tarry stools, unexplained weight loss, persistent abdominal pain, difficulty swallowing, ongoing nausea or vomiting, iron deficiency anemia, or diarrhea that is severe, recurrent or wakes a person from sleep,” Dr. Palam explained. “Patients should also be evaluated if they feel unusually fatigued, notice a loss of appetite, or have a family history of colorectal cancer, inflammatory bowel disease, celiac disease or other significant gastrointestinal conditions.”
“With bowel habits specifically, concerning changes may include new-onset constipation, persistent diarrhea, a sudden change in stool caliber, a feeling of incomplete evacuation, or needing to urgently rush to the bathroom on a regular basis,” Dr. Law noted. “While these symptoms are often caused by benign conditions, they can occasionally signal inflammation, infection, medication side effects or more serious underlying disease.”
Dr. Palam also shared that “one of the biggest mistakes patients make is assuming that symptoms such as bleeding, persistent abdominal pain, or changes in bowel habits are simply a normal part of aging or something they need to live with.”
“Most digestive conditions are much easier to evaluate and treat when identified early,” she said. “This is also a good opportunity to discuss colorectal cancer screening with a physician, since precancerous polyps can often be found and removed before they develop into cancer.”
“If symptoms are persistent, progressive or affecting quality of life, it is worth discussing them with a physician rather than continuing to self-manage indefinitely,” Dr. Law urged.
There is a gut and brain connection
“What we know best is that the gut-brain connection is bidirectional,” Dr. Law noted. “Stress activates the body’s fight-or-flight and cortisol pathways, which can change gut motility, increase visceral sensitivity, alter immune signaling and make symptoms such as cramping, urgency, reflux, nausea, bloating, diarrhea or constipation more noticeable.”
“In the other direction, ongoing digestive symptoms can increase worry, sleep disruption, and avoidance of normal activities, which can then further amplify gut symptoms,” Dr. Palam added. “This cycle is especially important in disorders of gut-brain interaction such as irritable bowel syndrome, where the problem is not ‘all in someone’s head,’ but rather reflects real changes in nerve signaling, gut sensitivity, motility, immune activity and sometimes the microbiome.”
Leaky gut is a physiologic phenomenon
“Leaky gut, or increased intestinal permeability, is a legitimate physiologic phenomenon. It accompanies many GI and systemic conditions such as inflammatory or ulcerating diseases,” Dr. Palam explained. “Multiple gastrointestinal symptoms are ascribed to ‘leaky gut’ including diarrhea, bloating, distension, abdominal pain, early satiety, nausea and postprandial fullness.
“However, the term ‘leaky gut syndrome’ has been widely popularized in social media, and it is not currently accepted as a formal medical diagnosis,” she added. “There is no proven disease that is cured simply by ‘sealing’ the gut, and it remains unproven that restoring barrier function improves clinical outcomes.”
Be mindful of taking antibiotics
“Everybody does have a signature microbiome, but it’s billions and billions of microorganisms that live in the gut and it starts from birth,” Dr. Seabrook said. “There is variation, but when the microbiome goes sideways—if you will—is when you start having some digestive issues.”
“The classic microbiome shift—in terms of disease—is clostridium difficile, or C. diff. It’s most associated with antibiotic use,” he said. “What that does is that causes a shift in the microbiome, which is called dysbiosis—a change in the composition or the diversity of the microbiome.
“With antibiotics, how they kill certain bacteria can cause dysbiosis, which is what allows organisms like clostridium difficile to propagate and become symptomatic in terms of an infection that produces a toxin that can be a life-threatening disease,” Dr. Seabrook added, noting “that’s becoming harder and harder to treat.”
“The most important step is to use antibiotics only when they are truly needed and to take them exactly as directed,” Dr. Palam said, noting that “patients should not save leftover antibiotics, share them with others, or stop early without checking with their doctor.”
“When antibiotics are needed, supporting the gut with simple habits can help,” Dr. Law said, such as staying hydrated, eating regular meals as tolerated and including fiber-rich foods.
Pay attention to ingredients
“Patients do not need to be afraid of every unfamiliar ingredient, but it is reasonable to pay attention to the overall pattern,” Dr. Law said. “Some additives, including certain emulsifiers and artificial sweeteners, are being studied because they may affect gut bacteria, gut lining, or symptoms in some people.
“Sugar alcohols, such as sorbitol, mannitol and xylitol, can also cause gas, bloating or diarrhea, especially in people with irritable bowel syndrome or sensitive digestive systems,” she added. “A practical way to think about this is: If a packaged food has a long ingredient list, is low in fiber and is high in added sugar or refined carbohydrates, it is probably not the best choice for gut health if eaten often.”
“For most patients, the goal is not perfection. It is to choose mostly minimally processed foods, increase fiber gradually, eat a variety of plant-based foods, and notice whether certain packaged foods or ingredients seem to trigger symptoms,” Dr. Law emphasized.
Try probiotics for relief
“When a patient comes in with the three symptoms of diarrhea, bloating and gas that are unexplained, I will often put them on probiotics,” Dr. Seabrook said. “If you look at the research, there’s not that many diseases that we know with confidence that probiotics really make things better.”
“And when people come in with those three symptoms especially and we know they don’t have colon cancer, ulcerative colitis or Crohn’s disease, that is when I recommend a trial of probiotics—the good bacteria for the gut—to see if it helps,” he said. “If they don’t do better, then I’ll do more. And that’s where I’ll start with a lot of people.”
“If symptoms get better with the probiotics once a day, then play around with it. If you’re doing better, take it every other day or every third day to see how you do,” Dr. Seabrook said, reiterating that “probiotics are the good bacteria for the gut and those include things like lactobacillus and Bifidobacterium and something called saccharomyces.
It is also important to know, said Dr. Palam, that “a probiotic that helps with one condition may not help with another, and more strains or a higher dose does not always mean a better product.”
“If patients choose a probiotic, we encourage them to look for a product that lists the exact strain or strains, the number of live organisms through the expiration date, storage instructions and the condition it has been studied for,” she explained. “It is best to choose a probiotic for a specific reason rather than taking one indefinitely without knowing whether it is helping. If there is no clear benefit after a reasonable trial, it is usually fine to stop.”
Prebiotics are good to use too
“The prebiotics are undigestible carbohydrates that are compounds within foods that help the good bacteria do even better,” Dr. Seabrook said, emphasizing “their compounds induce the growth and activity of the good bacteria of the gut.”
“There is also a combination of prebiotics and probiotics—called synbiotic—that are good too,” he said. “But the prebiotics help the good bacteria grow even more.”
“Patients can get prebiotics from foods such as onions, garlic, asparagus, bananas, oats, beans, lentils and other plant food,” Dr. Law noted. “For many people, increasing these foods slowly is more helpful and sustainable than starting with a supplement, although some patients may need to go gradually if they have bloating or IBS symptoms.”
“Anyone who is immunocompromised, seriously ill, has a central line, or has complex medical conditions should talk with a physician before taking probiotic-type supplements,” she emphasized.
Be careful with microbiome or gut health tests
“Direct-to-consumer microbiome or ‘gut health’ tests have gained a lot of popularity beyond their validated uses,” Dr. Palam said. “There is currently no validated microbiome test for diagnosis, prognosis, or therapeutic monitoring, and the field cannot yet reliably separate correlation from causation.”
“The one microbiome-directed therapy with clear proof is fecal microbiota transplantation for recurrent C. difficile which is a specific medical indication, not general wellness,” she emphasized.
Food sensitivity tests are also not validated
“IgG-based food ‘sensitivity’ testing is not validated to diagnose food intolerance or reliably direct which foods to exclude,” said Dr. Law. “Whereas, in patients with IBS, particularly IBS-D, a low-FODMAP diet is the best-evidenced dietary intervention for improving global symptoms, pain and bloating.
“But patients cannot just permanently stay on a restrictive diet,” she added. “Elimination should be targeted and time-limited. Even in conditions where food removal is genuinely therapeutic—such as eosinophilic esophagitis—broad multi-food elimination carries measurable costs to nutrition, quality of life, and eating behavior, and pre-existing restrictive eating is a contraindication.”
Skip gluten if it upsets your stomach
“We, as a country, eat a heavily processed diet … but the good news is we’re learning more about food intolerance and what helps,” Dr. Seabrook said. “We know about lactose intolerance, and we are testing all the time for celiac disease and gluten sensitivity.”
“With celiac disease, there are things that we can objectively look for. There’s a blood test called tissue transaminase that we can use to check and then we can take biopsies of the small intestine where gluten is absorbed,” he said. “Now if they’re positive, then we say you have celiac disease, but then there’s a large group of people who we may do both those tests and they’re both normal.
“Then they say that if they eat gluten, they feel bad. And if they don’t eat gluten, they feel good,” Dr. Seabrook added. “That’s where we get into this nonceliac gluten sensitivity, which means: If it bothers you, stay away from it.”
Stay away from colon cleanses
“Colon cleanses for ‘detoxification’ or general health are not supported by any methodologically rigorous trial,” Dr. Palam said, noting that “the literature contains multiple case reports and series of adverse effects.
“Reported harms range from cramping, nausea and electrolyte disturbances to more serious events,” she added. In fact, “one physiologic analysis warned irrigation may promote absorption of bacteria or toxins across the mucosa.”
Eat a well-balanced diet
“Studies have shown that diverse, fiber-rich, minimally processed plant-based diets promote a diverse microbiome, greater short-chain fatty acid (SCFA) production, a stronger gut barrier, and lower inflammation,” said Dr. Law, “whereas ultraprocessed diets reduce diversity and promote unhealthy, pro-inflammatory microbiome.”
Additionally, “Mediterranean diet, high fiber and polyphenol rich foods—such as fruits, vegetables, whole grains, legumes, nuts and olive oil—and fermented foods, which include kefir, yogurt, kimchi and sauerkraut, have shown to … promote healthy gut and may lower risk of inflammatory bowel disease and colorectal cancer,” she said.
Add more fiber as needed
“A high fiber diet is important for those who have diarrhea and for those who may be constipated,” Dr. Seabrook said, adding that “fiber is hydrophilic, which means loves water.”
“So, in people who have loose, watery stools, the fiber soaks up the excess water because it attracts water. It makes the stool less loose,” he explained. “Then the people with constipation—especially with hard, dry stools that may be difficult to evacuate—the fiber keeps water within the stool and keeps it softer and easier to evacuate.”
You may need to avoid bananas
“Bananas causing an upset stomach is not an uncommon thing,” Dr. Seabrook said. “Some people actually get a little bit more constipated with bananas. Then some people get a little bit more diarrhea with bananas. And others just say they hurt their stomach.”
“It’s just like any food tolerances. While we can’t pinpoint the reason why, if it upsets your stomach, try to avoid it,” he said.
Breastfeed for your baby’s gut health
“There’s no doubt that breastfeeding—with the immunoglobulins that are in the breast milk—is just healthy overall and good for the immune system of an infant,” Dr. Seabrook said. “And that will include the gut as well.”
“It takes a while to go from a relatively sterile gut to forming the signature microbiome of an individual,” he said. “But it seems that breastfeeding is beneficial for the infant even beyond gut health.”
Visit doctor if bowel habits change
“With unexplained abdominal pain, weight loss, blood in your stool and with a change in bowel habit, contact your doctor,” said Dr. Seabrook. “Before I do a colonoscopy, I always ask if the patient has had any unexplained change in bowel behavior, blood in stool, weight loss or abdominal pain.”
“Now, there are other reasons to see a gastroenterologist from the luminal digestive tract, meaning the esophagus, stomach, small intestine and large intestine,” he said. “Unexplained weight loss is oftentimes related to the gastrointestinal tract, so that should be evaluated.
“If people have trouble with swallowing, have a lot of heartburn and reflux, are throwing up blood or have persistent nausea or vomiting that’s not related to some transient illness, those are the common things that we see patients for,” Dr. Seabrook added.
