Walk through the supplement aisle and you’ll find shelves lined with products promising to improve digestion, reduce bloating, restore the microbiome, and even “heal” the gut. Yet despite the marketing, not every supplement is backed by strong science. Some gut health supplements can be helpful in specific situations, but what helps one person may do little for another.
“The great majority of my patients are already taking probiotics,” says Emeran Mayer, MD, Distinguished Research Professor in the Department of Medicine at UCLA. “My first question about probiotics when I see a new patient is whether they strongly feel they get a benefit. About 20% say yes. The remaining 80% are not sure.”
What Are Gut Health Supplements?
Gut health supplements are products intended to support the digestive system and the trillions of bacteria, fungi, and other microorganisms that live in the gastrointestinal tract, collectively known as the gut microbiome. Some supplements introduce beneficial bacteria, while others provide food for those bacteria or help your body digest nutrients more efficiently.
- Probiotics contain live beneficial microorganisms.
- Prebiotics are specialized fibers that nourish beneficial gut bacteria.
- Digestive enzymes help break down carbohydrates, proteins, and fats in the small intestine.
- Fiber supplements for digestion promote regular bowel movements, support healthy gut bacteria and are an important source of anti-inflammatory molecules, like butyrate.
- L-glutamine is an amino acid that may help maintain the cells lining the intestine.
Why Gut Health Matters
The digestive tract does much more than process food. It plays a central role in nutrient absorption, immune function, metabolism, and communication with the brain. The gut microbiome helps digest fiber into beneficial compounds called short-chain fatty acids, produces some vitamins, protects against harmful microbes, and helps regulate immune responses. Researchers also continue to uncover connections between the gut and the brain, known as the gut-brain axis, which may influence mood, stress responses, and overall health.
Because diet shapes the microbiome every day, food remains the foundation of good gut health. After reviewing a patient’s eating habits, Dr. Mayer says he often discovers that “most patients eat a diet deficient in fruits and vegetables, our main source of fiber.” Rather than recommending supplements first, his initial goal is helping patients gradually improve their diets, ideally with guidance from a registered dietitian. He recommends aiming for at least 30 different plant foods each week. That includes plenty of fruits and vegetables, but also beans, herbs, berries, nuts, seeds, whole grains, and spices. “Each of these plant foods feeds different microbes in your gut,” he notes. More variety in your diet leads to more microbial diversity.
Top Gut Health Supplements
Probiotics
Probiotics are live microorganisms that can temporarily add beneficial bacteria to the digestive tract. They’re found naturally in fermented foods such as yogurt, kefir, sauerkraut, and kimchi. For people experiencing gastrointestinal issues after taking a course of antibiotics, a probiotic supplement may be beneficial. Antibiotics kill good bacteria along with the bad, creating an imbalanced microbiome.
But finding a good-quality supplement can be a challenge. A study from researchers at the University of California Davis tested 16 probiotic supplements that claimed to have certain strains of bacteria. Only one matched its label claims in all samples tested. There was also variation in the diversity of cultures in a product.
“Once I make a recommendation about a probiotic, I recommend products that have undergone rigorous testing, demonstrate that the probiotics survive the harsh gastric environment and reach the large intestine in sufficient amounts, and have some clinical trial evidence,” Dr. Mayer says. “While most current probiotic supplements would not survive rigorous evaluations in human clinical trials, companies are working on ‘third generation’ bioengineered probiotics, which will carry out specific functions in the human gut in the future.”
Prebiotics
Unlike probiotics, prebiotics are not living organisms. Instead, they are specialized types of fiber that feed the beneficial bacteria already living in your gut. As gut bacteria ferment prebiotic fibers, they produce compounds that nourish the cells lining the colon and help maintain a healthy microbial balance.
You can get prebiotics from foods such as onions, garlic, asparagus, oats, bananas, chicory root, and legumes. Dr. Mayer says he considers prebiotic supplements only after first encouraging patients to improve their overall eating pattern.
“If they cannot achieve this goal because of side effects, primarily bloating, I recommend adding fiber supplements like acacia or oat fiber,” he says. “My first approach is always the dietary approach.”
Digestive Enzymes
Digestive enzymes help break down carbohydrates, proteins, and fats into smaller molecules that your body can absorb. Your pancreas naturally produces these enzymes in sufficient amounts, but certain relatively rare medical conditions, including chronic pancreatitis, cystic fibrosis, pancreatic cancer, and some gastrointestinal disorders, can reduce enzyme production and lead to poor digestion.
For people with pancreatic enzyme insufficiency, prescription digestive enzymes can improve symptoms and nutritional status. Over-the-counter digestive enzyme supplements, however, are a different story. Many healthy people take digestive enzymes hoping they’ll reduce occasional bloating or discomfort after meals, but research supporting routine use is limited. In many cases, symptoms blamed on poor digestion are actually caused by food intolerances, irritable bowel syndrome (IBS), constipation, or eating large, high-fat meals.
Fiber Supplements
Fiber is one of the most effective dietary tools to support gut health. Unlike most carbohydrates, fiber isn’t fully digested and cannot be absorbed in the small intestine. Instead, it travels to the ileum and the large intestine, where gut bacteria ferment it, producing beneficial compounds that exert anti-inflammatory effects in the gut and throughout the body, help nourish the intestinal lining, and support a rich and diverse microbiome. Fiber also promotes regular bowel movements, helps control blood sugar, and may help lower cholesterol. Unfortunately, most Americans consume only about 15 grams (g) of fiber each day, compared to the recommended dose of 25g to 38 g.
Dr. Mayer says this is an important issue he addresses. His first recommendation is to gradually increase fiber intake through diet, working toward as much as 40 grams per day, if tolerated, often with guidance from a registered dietitian.
When people can’t tolerate enough fiber-rich foods because of bloating or other digestive symptoms, fiber supplements can help fill the gap.
- Psyllium is a soluble fiber that improves constipation and also may help lower cholesterol.
- Methylcellulose is less likely to cause gas than some other fiber supplements for digestion.
- Inulin is a prebiotic fiber that feeds beneficial gut bacteria but often causes symptoms of bloating.
- Acacia fiber is a gentle prebiotic that some people tolerate better than inulin.
Always increase fiber gradually and drink plenty of water. Adding too much too quickly can temporarily worsen gas and bloating.
L-Glutamine
L-glutamine is an amino acid that serves as an important fuel source for the cells lining the small intestine. Because of its role in maintaining the intestinal barrier, it’s often marketed as one of the best supplements for leaky gut. However, the evidence doesn’t live up to many of the claims.
“There is no objective evidence that any gut supplement gets rid of ‘leaky gut,’ which is a controversial diagnosis anyway,” Dr. Mayer says. “There is some clinical evidence to support the use of probiotics for symptoms of bloating, but there are many other causes for bloating symptoms that can be treated by dietary modifications and stress reduction techniques.”
Research suggests L-glutamine for gut health may benefit some hospitalized patients, people recovering from major surgery or trauma, or individuals with specific medical conditions that place extraordinary stress on the intestinal lining. But for otherwise healthy adults with vague digestive complaints, high-quality evidence supporting routine supplementation is lacking.
If you’re considering L-glutamine for chronic digestive symptoms, talk with your healthcare provider first to determine whether another underlying condition requires evaluation.
How to Choose the Right Gut Health Supplement
Always start with natural ways to support gut health, particularly diet. Dr. Mayer says he always begins with nutrition rather than supplements. “I recommend working with a dietitian to personalize the diet to increase the consumption of a diverse amount of fruits and vegetables without developing symptoms of bloating and gas.” If patients cannot tolerate enough probiotic foods or fiber-rich foods, he recommends supplements in addition to dietary improvements, not instead of them.
When shopping for supplements, consider these factors:
- Look for clinical evidence.Choose products that have been studied in people in high-quality studies, not just in laboratory experiments.
- Know the specific strain. Different probiotic strains produce different effects.
- Choose reputable manufacturers.Look for products that undergo independent quality testing.
- Be realistic.No supplement can compensate for a poor diet, lack of sleep, chronic stress, or inactivity.
Safety Tips and When to See a Doctor for Gut Issues
Although most gut health supplements are considered safe for healthy adults, “natural” doesn’t always mean risk-free.
Some probiotics can cause temporary gas or bloating when first started. Fiber supplements may worsen bloating if increased too quickly or taken without enough fluids. Digestive enzymes and herbal blends may interact with medications or be inappropriate for some medical conditions.
Most importantly, don’t let supplements delay a proper medical evaluation. If you experience significant abdominal symptoms, seek medical advice to rule out conditions like inflammatory bowel disease, celiac disease, or colon cancer, Dr. Mayer says.
Seek medical care promptly if you have:
- Blood in the stool
- Unexplained weight loss
- Persistent diarrhea lasting more than a few weeks
- Severe or worsening abdominal pain
- Difficulty swallowing
- Ongoing vomiting
- New digestive symptoms after age 50
- A family history of colorectal cancer or inflammatory bowel disease
Dr. Mayer notes that in the absence of these “red flag” symptoms, IBS is one of the most common explanations for chronic digestive complaints. In those cases, treatment often involves dietary counseling, stress reduction, gut-directed behavioral therapies such as cognitive behavioral therapy or hypnosis, and, when appropriate, medication. For most people, the healthiest gut doesn’t start with a supplement bottle. It starts with a varied, fiber-rich diet, regular physical activity, adequate sleep, and stress management.
