A healthy gut can strengthen your immune system and prevent disease. Here are foods that will help build your gut microbiome to improve your health from the inside out.
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Known as the microbiome, your gut is home to millions of bacteria and other microbes—both good and bad—and can influence your health in many ways. The key is to balance the ratio of good to bad bacteria. According to a 2019 review in the journal Microorganisms, the "right balance" is different for everyone, as each person has their own personal microbiome profile that is initially influenced by birth gestational date, type of delivery, methods of infant milk feeding and the weaning period. Beyond that, there are several other influences on the health of your microbiome, including antibiotic use, what types of microbes are inhabiting your gut, exercise and other lifestyle choices, including diet.

According to a large 2019 review in the journal Nutrients, what you eat directly influences the makeup of bacteria in your gut. A healthy gut helps keep chronic diseases like heart disease and cancer at bay, reduces inflammation, keeps your brain healthy and helps you maintain a healthy weight. A 2019 study published in Nature Microbiology suggests that a healthy microbiome can even help with depression.

It's never too late to change your diet to support better gut bacteria. The same Nutrients review suggests that switching from a mostly animal-based diet to a mostly plant-based diet (and vice versa) can change the makeup of your microbiome in as little as 24 hours—for better or for worse.

So how do you improve your own microbiome?

Eat more: Probiotics, prebiotics, fiber, polyphenols and fermented foods

Eat less: Artificial sweeteners, red meat, processed foods and alcohol.

Here, we break down each category and explain what each one means.

Probiotics

Simple Sauerkraut

Probiotics are beneficial bacteria and can be found in fermented foods like sauerkraut, kimchi, miso and yogurt. Eating foods that are naturally rich in probiotics adds good bacteria to your gut. The most common types of good bacteria are Lactobacillus and Bifidobacterium, with each having its own specific strains. In addition to helping balance your gut bacteria and prevent chronic disease, probiotics can help if you have diarrhea, boost your immunity and keep your heart and skin healthy.

1. Sauerkraut

Sauerkraut is made from cabbage and salt. During the fermentation process, microorganisms eat the sugar present in cabbage and produce carbon dioxide and acids. The probiotics created during fermentation assist with digestion and add good bacteria to your gut.

One cup of raw cabbage has 36% of your Daily Value for vitamin C and 56% DV for vitamin K, per the USDA.

Enjoy sauerkraut on a hot dog, substitute it for pickles on a sandwich or burger, add it to potato salad, or put it on a cheese plate and serve your friends something good for their guts.

2. Kimchi

Kimchi, also fermented cabbage, is the spicy Korean cousin to sauerkraut. It can have scallions, radishes and shrimp added to give it more flavor. Look for it in the refrigerated section near sauerkraut, other Asian sauces and pickles.

Kimchi is delicious added to a fried rice bowl with veggies and an egg.

3. Kefir

Kefir is like drinkable yogurt. It's made when kefir grains, which are colonies of yeast and lactic acid bacteria, ferment the sugars in milk, giving it a slightly thicker consistency and tart flavor. Similar to yogurt, kefir is packed with probiotics.

Buy plain kefir (instead of flavored) to skip added sugars or make your own kefir. Due to fermentation, kefir has a slightly tart and acidic taste, which makes it a tasty addition to a breakfast smoothie in place of milk. Or try substituting kefir for milk in one of our overnight oats recipes for a healthy combo of probiotics and fiber.

4. Kombucha

Kombucha is a tart, fizzy tea made by adding a SCOBY (symbiotic colony of bacteria and yeast) and sugar to green or black tea. It's then fermented for a week or more. During fermentation alcohol and gases are produced, giving the kombucha natural carbonation. The amount of alcohol is usually less than 0.5% alcohol by volume (ABV)—and commercially-prepared kombucha is required to keep it no higher than this amount (federal law states that any product with more than 0.5% ABV must be regulated and marketed as an alcoholic beverage). Some homemade kombucha's, however, have been found to have closer to 2-3% ABV.

To keep the alcohol levels down on your homemade kombucha brew, make sure to keep it cold and refrigerated and shorten the fermentation time. You could also try using a different type of tea. One 2019 study in the journal Nutrients found that kombucha made with rooibos tea had lower ethanol (a type of alcohol) and acetic acid (aka vinegar acid) concentrations compared to kombucha made with black or green tea.

When fermenting tea, lactic acid bacteria are produced, which are known to function as a probiotic. When consuming kombucha made from green tea, you'll also get the antioxidant properties associated with tea. Keep in mind that some kombuchas, like those made from black tea, contain caffeine. Others have artificial sweeteners, which can negatively alter gut bacteria (and defeat the purpose of drinking it), so read labels—or make your own.

5. Miso

Miso is a fermented paste made from soybeans, barley or rice. Similar to other fermented foods, beneficial bacteria are produced in the fermentation process. You'll also get some protein if you eat miso made from soybeans. A little bit goes a long way, which is good since miso is also high in sodium.

Miso is great added to sauces, dressings and soup bases. Try it on this Miso-Maple Salmon.

6. Tempeh

Tempeh is similar to tofu in that it's made from soybeans, but unlike tofu, tempeh is a fermented food, so it contains probiotics. Tempeh is made when soybeans are fermented and then pressed into a cake. It can then be grilled, sautéed or baked. Tempeh is high in protein, making it a good option for vegetarians and vegans. It's also packed with B vitamins, calcium, manganese, zinc and copper.

Try marinating then grilling tempeh, and add it to a salad. Or make tempeh grain bowls.

7. Yogurt

Yogurt is probably the most popular probiotic and for good reason. It's made when good bacteria are added to milk, where they metabolize lactose to form lactic acid and other beneficial microbes. Look for yogurt labeled with the "Live & Active Cultures" seal, which guarantees 100 million probiotic cultures per gram at the time it was manufactured. A quick look at the ingredients list will also show you if there are bacteria in the yogurt. Don't eat dairy? The probiotics in yogurt help digest some of the lactose (milk sugar) so if you're lactose-intolerant, you may be able to enjoy yogurt (and kefir). Plus, many companies now make dairy-free and vegan yogurts that contain probiotics.

Prebiotics

muesli with raspberries

Pictured Recipe: Muesli with Raspberries

Once you've got good bacteria more established in your gut, you need to feed them so they can flourish and keep making more good bacteria. "Prebiotics are fibers that feed the beneficial probiotics in your gut," says Dianne Rishikof, M.S., RDN, LDN, IFNCP, a registered dietitian, integrative & functional medicine nutritionist and president and CEO of Health Takes Guts, a nutrition counseling private practice. "Ingredients to look for include galactooligosaccharides, fructooligosaccharides, oligofructose, chicory fiber and inulin." Fructans and cellulose are two other prebiotic fibers.

But don't get bogged down in the scientific names. In fact, you won't see most of these compounds listed on a label because they are present in foods that don't have labels—like fruits and vegetables.

Focus on a variety of whole foods. "It's all about diversity, getting as much variety of plant-based foods as possible and hitting our recommended fiber intake of 30 grams per day," says Megan Rossi, Ph.D., B.H.Sc., RD, APD, founder of The Gut Health Doctor. Apricots, dried mango, artichokes, leeks, almonds, pistachios and legumes, as well as polyphenol-rich foods, such as blueberries, strawberries, prunes, apples, flaxseed, olives and extra-virgin olive oil, are extra-high in prebiotics, Rossi writes in her book, Love Your Gut.

8. Jerusalem Artichokes

Though commonly referred to as Jerusalem artichokes this tuber isn't an artichoke at all, but rather, is part of the sunflower family. Also known as sunchoke, sunroot, or wild sunflower, they look similar to ginger root. One cup of Jerusalem artichokes delivers 3 grams of protein, 2.4 grams of fiber, 25% DV for thiamin, and 28% DV for iron, per the USDA. According to a 2019 review article in Annals of Agricultural and Environmental Medicine, 80% or more of the carbohydrates in sunchokes is inulin, a prebiotic fiber that provides food for your critters. Thiamin (a B vitamin) supports healthy hair, skin and nails, and iron helps form red blood cells.

Try sunchokes roasted with olive oil and garlic or raw in salads (they have a texture similar to water chestnuts).

9. Leeks

Leeks are high in good-for-the-gut fructans. According to the USDA, one cup of leeks has 35% DV for vitamin K and 12% DV for vitamin C. Vitamin K helps your blood clot, and vitamin C is an antioxidant.

Leeks can be added to almost any dish—try adding them to an omelet or sautéing them to mix with roasted potatoes. Alternatively, rub whole leeks with oil and grill briefly; then toss with your favorite vinaigrette. Try our Oven-Braised Leeks that require only 15 minutes of prep.

10. Onions

Onions are chock-full of inulin, fructans and fructooligosaccharides (FOS). Not only are FOS a prebiotic that help build up gut flora, but according to a 2022 review of the literature published in the International Journal of Molecular Sciences, they also help to improve a plethora of conditions, including diarrhea, osteoporosis, atherosclerosis, gastrointestinal disorders, cardiovascular disease and type 2 diabetes.

Onions are highly versatile: Add to soup or salad, grill and put on top of a turkey burger, or roast with herbs and serve as a side.

11. Raspberries

According to the USDA, one cup of raspberries has a whopping 8 grams of fiber, about one-third of your Daily Value (DV). Raspberries are a rich source of polyphenols, potent antioxidants that your gut microbes love to nosh. According to a 2018 review in the journal, Neural Regeneration Research, polyphenols act as prebiotics by enhancing the growth of beneficial bacteria and inhibiting the growth of pathogens.

Raspberries are delicious eaten fresh but are just as nutritious purchased frozen and thrown into a smoothie. Or add them to yogurt, oatmeal or a high-fiber cereal.

12. Beans and legumes

Many steer clear of beans for fear of having gas but flatulence is actually a good sign that your gut bacteria are hard at work. When beans and legumes, such as black beans, chickpeas, peas, lentils and white beans, reach the large intestine (colon), they are still intact. It's there that gut bacteria feed on them. This process is called fermentation. And the byproduct? Gas. So while it may be awkward, you can feel good about it because your microbes are doing what they're supposed to.

Canned beans are a favorite—pick three types, rinse and mix for a simple bean salad. Or throw black beans on top of tacos. Lentils are delicious in soup—even dried lentils take only 15-20 minutes to cook, so they make for a quick and easy add-in for your favorite soups and stews.

13. Asparagus

Asparagus is a powerful prebiotic for the gut, due to its level of fructans (inulin and FOS). And according to a 2020 study in the journal Metabolites, it is also loaded with antioxidants, natural chemicals that fight off free radicals and other inflammatory compounds in the body.

Roasted asparagus can be made in just 15 minutes—simply toss the spears with olive oil, salt and pepper and oven-roast at 400°F for 10 to 15 minutes. Or shave raw asparagus over a green salad. Asparagus is also delicious added to pasta or an omelet.

14. Garlic

Garlic may help reduce the risk of heart disease and is also anti-inflammatory in the body. Inulin and fructooligosaccharides are the two main fibers in garlic—a dynamic prebiotic duo. But that's not all garlic is good for. According to a 2020 review in the journal Antioxidants, garlic also has shown positive health effects regarding cancer, cardiovascular disease, metabolic disorders, blood pressure and diabetes, thanks to it's antioxidant, anti-inflammatory and lipid-lowering properties. That's a whole lot of benefits in those little cloves!

If you don't like messing with peeling garlic cloves (and the smell it leaves on your hands), a good garlic press is invaluable. You can put the whole clove in there without having to peel it (yes, please!). Garlic can be used to season almost any dish. Sauté it with onions and mix it into a stir-fry or pasta.

15. Bananas

Green bananas (the unripe ones) are best for the gut because they contain resistant starch, a type of indigestible fiber that produces more beneficial bacteria when your microbes feed on it, according to a 2019 review in the journal Nutrients. Resistant starch can also be created by cooking grains and then cooling them, due to a naturally-occurring process called retrogradation, per a 2022 study in the journal Nutrition & Diabetes. So go ahead and make barley and brown rice in bulk for the week. Bonus: Ripe bananas are full of fiber too, which helps keep you fuller longer.

Eat bananas with peanut or almond butter for protein, healthy fat and an extra dose of fiber. Add them to overnight oats, Greek yogurt or a high-fiber cereal, or use them as a topping for whole-wheat toast.

16. Pears

Pears are a prebiotic food for the gut and also contain pectin, a compound that helps lower cholesterol. One medium pear is just 100 calories but has 5.5 grams of fiber, according to the USDA.

Add a dash of cinnamon to fresh pear slices for a tasty snack, bake a pear crisp, or mix diced pear into oatmeal for additional cholesterol-lowering benefits, thanks to the fiber in oatmeal, known as beta-glucan.

17. Watermelon

Watermelon is naturally high in fructan. According to the USDA, one cup of this juicy fruit has 14% DV for vitamin C, an antioxidant that fights inflammation, is the building block of collagen and increases the absorption of iron.

Watermelon is a summer staple that is tasty eaten plain. Find that boring? Make a refreshing beverage with it like we do in our Watermelon-Basil Agua Fresca or combine it with feta and mint for a summery salad.

Polyphenols

"Polyphenols are a type of plant chemical that gut microbes love," says Rossi. They are found in berries, apples, artichokes, red onions, tea, dark chocolate and other fruits and vegetables. Gut bacteria feed on polyphenols and produce beneficial substances, which in turn, have a positive influence on certain conditions, including cancer, diabetes, cardiovascular diseases, and aging, according to a 2020 review article in the journal Food Frontiers.

Worst Foods for Gut Health

1. Artificial Sweeteners

Artificial sweeteners, such as aspartame, saccharin and sucralose, have zero calories and no sugar. They pass through the body without being digested, yet they come into contact with the microflora in the gut, negatively changing the composition, according to 2021 research published in the International Journal of Molecular Sciences.

For now, keep an eye out for aspartame, saccharin and sucralose on the label of processed foods and drinks like diet sodas and other and zero-calorie beverages as well as some yogurts, granola bars and protein bars. These foods and drinks often come with added sugar and salt anyway, so limiting them would be a positive change. Try kombucha in place of soda for a bubbly beverage with good-for-the-gut probiotics.

2. Red Meat

L-carnitine, a compound found in red meat, interacts with gut bacteria to produce trimethylamine-N-oxide (TMAO), according to a 2022 study from the Cleveland Clinic and Tufts University. The study, published in the American Heart Association's journal, Arteriosclerosis, Thrombosis, & Vascular Biology, shows how TMAO is associated with atherosclerosis—a buildup of plaque in the arteries. This goes to show that the link between red meat and heart disease is not just about saturated fat and sodium: How gut bacteria interact with red meat may play a role.

Eat red meat in moderation, and choose fatty fish, white fish, chicken or plant-based proteins like tofu and tempeh on the regular.

3. Processed and Refined Foods

"While I wouldn't go as far as to say you need to cut certain foods out of your diet forever—food is about enjoyment too, after all—limiting highly processed foods loaded with additives and salt will do you and your gut microbes good," says Rossi. It's hard to study "processed foods" as a whole because each food has different ingredients, but the biggest issue with processed and refined foods is that they lack diversity and fiber and are often filled with added sugars, salt, artificial sweeteners and/or additives and preservatives. Your microbiome thrives on the diverse fibers and polyphenols that come from eating a variety of colorful fruits, vegetables and whole grains.

4. Alcohol

Research studies, like the 2022 review published in Frontiers in Cellular and Infection Microbiology, have found that alcoholism negatively impacts the intestinal microbiome. And while research is scant on the effects of moderate alcohol consumption on gut bacteria, one 2021 study published in Frontiers in Cardiovascular Medicine suggests that moderate alcohol intake might have a positive influence on both the gut microbiome and cardiovascular disease. If you enjoy drinking, be sure to do so in moderation, which is one drink per day for females and two for males.

The Bottom line

It all comes back to eating lots of fruits, vegetables, nuts, seeds and whole grains for prebiotics (food for the bacteria) and fermented foods like yogurt and kombucha for probiotics (good bacteria).

If you do not normally include these foods in your diet, adding them all at once might cause some unwanted gas and bloat. Start with small amounts, and once a week, increase the amount a little bit, determining how much to add based on how you feel.

Eat processed foods in moderation and limit added sugars, salt, artificial sweeteners and alcohol to keep your gut critters happy and your risk of chronic diseases low.