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Oct 28, 2024

Gut-Healthy Foods to Optimize Your Health

A healthy gut supports your immune system and helps prevent disease. Here are foods that feed and maintain your gut microbiome to improve your health from the inside out. Lainey is a weight-loss

A healthy gut supports your immune system and helps prevent disease. Here are foods that feed and maintain your gut microbiome to improve your health from the inside out.

Lainey is a weight-loss dietitian who helps people ditch diets, change their habits and create a healthy lifestyle that lasts. She has Master's in Nutrition Communication from the Tufts Friedman School of Nutrition Science and Policy and completed her dietetics training at Massachusetts General Hospital, a Harvard teaching hospital. She writes on a variety of topics including weight loss, gut health, pregnancy, breastfeeding and trendy diets. When she's not writing or counseling, you can find her on a run, out to brunch, or with coffee in hand trying to keep up with her two little boys.

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 within the gut microbiome. The "right balance" is different for everyone, as each person has their own personal microbiome profile that is initially influenced by several factors including how your mother gave birth to you and whether you were fed infant formula or breast milk.

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 healthy microbiome can even help with depression.

It's never too late to change your diet to support better gut bacteria. There is even evidence suggesting that what you eat can change the makeup of your microbiome overnight—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 are the beneficial bacteria that live in your gut 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.

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. Try to make your own sauerkraut. Most store-bought sauerkraut is pasteurized, which kills bad bacteria as well as the beneficial bacteria created through fermentation.

One cup of sauerkraut has 4 grams of fiber, per the USDA. Probiotics in the gut use fiber as fuel.

Enjoy sauerkraut with grilled chicken, 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. Try our Sauerkraut & Sausage Casserole for a warm, comforting meal any night of the week.

Kimchi, also fermented cabbage, is the spicy Korean cousin of 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, or better yet make your own to maximize probiotic content.

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

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, as long as the store-bought brand you buy uses milk that is pasteurized prior to the fermentation process. Pasteurization before fermentation ensures kefir contains live and active probiotics when you consume it.

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.

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). Pasteurization is used to limit alcohol content, which means commercial kombucha contains few if any probiotics. Some homemade kombuchas, 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. Research has 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.

It's important to note that kombucha is not recommended for people with compromised immune systems or if you're pregnant or breastfeeding. This is partly due to the alcohol content (small as it may be), and because many commercial brands are not pasteurized and could potentially cause illness. Kombucha is also not recommended for children.

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.

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 Gochujang-Glazed Tempeh & Brown Rice Bowls.

Yogurt is probably the most popular probiotic and for a 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. Do you have trouble digesting lactose? 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. If you don't eat dairy, many companies now make dairy-free and vegan yogurts that contain probiotics. Or you could make your own Vegan Coconut Yogurt.

Pictured Recipe: Muesli with Raspberries

When you're trying to establish more probiotic bacteria in your gut, you need to feed them with prebiotics 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 and 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 g 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.

Though commonly referred to as Jerusalem artichokes, this tuber isn't an artichoke at all but rather a part of the sunflower family. Also known as sunchoke, sunroot or wild sunflower, they look similar to gingerroot. One cup of Jerusalem artichokes delivers 2.4 g of fiber, per the USDA. Research has indicated that 80% or more of the carbohydrates in sunchokes is inulin, a prebiotic fiber that provides food for your gut bacteria.

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

Leeks are high in good-for-the-gut fructans. According to the USDA, 1 cup of leeks has 1.6 grams of fiber and just 54 calories.

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.

Onions are chock-full of inulin, fructans and fructooligosaccharides (FOS). Not only are FOS prebiotics that help build up gut flora, 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.

According to the USDA, 1 cup of raspberries has a whopping 8 g 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. Polyphenols act as prebiotics by enhancing the growth of beneficial bacteria and inhibiting the growth of pathogens.

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

Many steer clear of beans for fear of having gas, but flatulence can be a sign that your gut bacteria are hard at work. When the fiber in beans and legumes, such as black beans, chickpeas, peas, lentils and white beans, reaches the large intestine (colon), it's still intact. It's there that gut bacteria feed on them. This process is called fermentation. And the byproduct may be some gas.

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.

Asparagus is a powerful prebiotic for the gut, due to its level of fructans (inulin and FOS). Asparagus 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 when added to pasta or an omelet.

As part of a healthy diet, garlic is 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. Garlic also has shown positive health effects regarding cancer, cardiovascular disease, metabolic disorders, blood pressure and diabetes, thanks to its 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.

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. 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.

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

Watermelon is naturally high in fructans. According to the USDA, 1 cup of this juicy fruit is also 91% water by weight and adequate fluid is necessary to help fiber prevent constipation and keep the gut functioning.

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

"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.

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. However, it's unclear how artificial sweeteners actually affect your health.

For now, keep an eye out for aspartame, saccharin and sucralose on the label of processed foods and drinks like diet sodas and other 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.

Research has found that L-carnitine, a compound found in red meat, interacts with gut bacteria to produce trimethylamine-N-oxide (TMAO), which is associated with atherosclerosis—a plaque buildup in the arteries. This shows 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, as well.

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

"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.

Research studies have found that alcoholism negatively impacts the intestinal microbiome. But it's not just excessive alcohol intake. While more research needs to be done, there is evidence that negative changes in your microbiome take place within 30 minutes of drinking alcohol. If you enjoy drinking, be sure to do so in moderation, which is one drink per day for females and two for males.

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.

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