Key takeaways
- Eating more fiber from a variety of plants is the best-supported thing you can do for your gut. Most Americans eat far less than recommended.
- Fermented foods such as yogurt, kefir and kimchi increased gut microbe diversity in a randomized trial at Stanford.
- Probiotic supplements help in some specific situations, but healthy people don't necessarily need one.
- Sleep, regular movement and stress management matter too, though the research on them is less direct.
What "gut health" means
Your digestive tract is home to trillions of bacteria, fungi and other microbes, together called the gut microbiome. These microbes help break down fiber, produce some vitamins and short-chain fatty acids, and interact with your immune system.
There is no single test or number that defines a "healthy gut." Researchers often look at microbial diversity, meaning how many different types of microbes live there. Higher diversity is generally linked with better health, though scientists are still working out cause and effect.
In everyday terms, a healthy gut usually means regular, comfortable digestion without frequent bloating, pain, constipation or diarrhea.
1. Eat more fiber, from more kinds of plants
Strong evidence
Fiber is the main food source for many beneficial gut bacteria. When they ferment it, they produce short-chain fatty acids that help nourish the cells lining your colon. Fiber also adds bulk to stool and supports regularity.
The Dietary Guidelines for Americans recommend about 14 grams of fiber for every 1,000 calories you eat, which works out to roughly 25 grams a day for many women and 30–38 grams for many men. Most Americans fall well short of this.
How to do it:
- Add beans, lentils or chickpeas to a few meals each week.
- Choose whole grains such as oats, brown rice and whole-wheat bread over refined versions.
- Aim for a mix of vegetables, fruits, nuts and seeds. Different fibers feed different microbes.
- Increase fiber slowly over two to three weeks and drink enough water. A sudden jump can cause gas and bloating.
2. Add fermented foods
Moderate evidence
In a 2021 randomized study published in Cell, researchers at Stanford assigned healthy adults to either a high-fermented-food diet or a high-fiber diet for 10 weeks. The fermented-food group, eating foods like yogurt, kefir, kimchi, sauerkraut and kombucha, showed a steady increase in microbiome diversity and a decrease in several markers of inflammation. The high-fiber group did not show the same rise in diversity during the study period.
The study was small, with 18 people per group, so it's a promising result rather than proof. Still, fermented foods are cheap, safe for most people and easy to add.
How to do it: start with one serving a day, such as plain yogurt with live cultures, a glass of kefir or a forkful of sauerkraut with dinner, and build up. Check labels: some store-bought sauerkraut and pickles are pasteurized or made with vinegar and contain no live cultures.
3. Consider whether you need a probiotic
Moderate evidence, for specific uses
Probiotics are live microbes taken as supplements. According to the National Center for Complementary and Integrative Health (NCCIH), some probiotics may help prevent diarrhea linked to antibiotics and may ease some symptoms of irritable bowel syndrome. Results depend heavily on the specific strain and dose, and many products haven't been tested at all.
For healthy people without digestive symptoms, there's no strong evidence that a daily probiotic improves gut health beyond what a good diet does. If you do try one, choose a product that lists the full strain name (for example, Lactobacillus rhamnosus GG), not just the species.
4. Move your body regularly
Limited evidence for the gut specifically
Regular physical activity helps keep food moving through the digestive tract and is linked with lower constipation risk. Some studies have found differences in gut microbes between active and inactive people, but it's hard to separate the effect of exercise from diet and other habits. Exercise has so many proven benefits elsewhere that it's worth doing regardless.
5. Protect your sleep and manage stress
Limited evidence
The gut and brain communicate constantly through nerves, hormones and immune signals, often called the gut-brain axis. Many people notice digestive symptoms get worse during stressful periods or after poor sleep. Research in humans linking sleep and stress directly to microbiome changes is still early, but adults generally need seven or more hours of sleep a night, and practices such as walking, breathing exercises or therapy can help with stress.
6. Use antibiotics only when you need them
Antibiotics can be lifesaving, but they also reduce many of the helpful bacteria in your gut, and recovery can take weeks or longer. Don't ask for antibiotics for colds or flu, which are caused by viruses. If you're prescribed antibiotics, take them exactly as directed.
What doesn't have good evidence
- "Gut cleanses" and detox teas. Many contain laxatives. They don't "reset" your microbiome and can cause dehydration with regular use.
- At-home microbiome tests. They can tell you which microbes were in a stool sample, but there's no agreed standard for what a "good" result is, and they can't diagnose disease.
- Eliminating food groups without a reason. Cutting out whole groups, such as all grains, often reduces fiber. Elimination diets are best done with a doctor or dietitian.
When to see a doctor
Lifestyle changes are a good start, but some symptoms need medical attention. See a doctor if you have blood in your stool, black stools, unexplained weight loss, ongoing pain, trouble swallowing, frequent vomiting, or a change in bowel habits that lasts more than a few weeks, especially if you're over 45.
The bottom line
The most reliable way to support your gut is also the least exciting: eat more fiber from a variety of plants, add a serving of fermented food most days, stay active and look after your sleep. Supplements can play a role in specific situations, but they work best on top of these basics, not instead of them.