Your gut is home to trillions of bacteria and other microbes, collectively called the gut microbiome. Research links a diverse microbiome to better digestion and possibly to immunity and metabolism, although many claims online go well beyond what science has shown. The good news is that the foods that feed a healthy gut are the same ones recommended for overall health.
Fiber-rich plant foods
Fiber is food for your gut bacteria. When they ferment it, they produce short-chain fatty acids that nourish the cells lining the colon.
- Legumes: beans, lentils, chickpeas.
- Whole grains: oats, barley, brown rice, whole wheat.
- Vegetables and fruit, eaten with their skins when possible.
- Nuts and seeds: almonds, chia, flax.
Diversity seems to matter: some research suggests that eating a wide variety of plants each week is linked to a more diverse microbiome.
Prebiotic foods
Some fibers are especially good food for beneficial bacteria: inulin and related fibers found in onions, garlic, leeks, asparagus, Jerusalem artichokes, slightly green bananas and oats.
Fermented foods
Yogurt and kefir with live cultures, sauerkraut and kimchi (unpasteurized, from the refrigerated section), miso, tempeh and kombucha contain live microbes. A 2021 Stanford study found that a diet high in fermented foods increased microbiome diversity and reduced some markers of inflammation. Choose versions without lots of added sugar.
Polyphenol-rich foods
Berries, cocoa, green tea, coffee, olive oil and colorful vegetables contain polyphenols that gut bacteria break down, and that may support beneficial species.
What about probiotic supplements?
Probiotic supplements may help in specific situations, such as some types of diarrhea, but evidence for general gut health in healthy people is limited, and different strains have different effects. The NIH’s overview of probiotics explains what is known. Food is usually the better starting point.
What to limit
Diets high in ultra-processed foods, added sugar and low in fiber are associated with a less diverse microbiome. Increase fiber gradually and drink enough water to avoid bloating.
When to see a doctor
Ongoing bloating, pain, changes in bowel habits, blood in the stool or unexplained weight loss need medical advice, not just diet changes.
For practical ways to add fiber, see the best ways to eat more fiber. Making yogurt at home is covered in how to make homemade yogurt.
