9 Fermented Foods to Feed a Healthy Gut

By Matthew Kadey, R.D. |

A healthy gut microbiome can help with everything from immunity to weight management. Give yours a boost with these probiotic-rich foods.

Improve gut health with these fermented foods

You’ve probably been taught that germs are bad. That’s why you might carry a small bottle of hand sanitizer with you at all times. It’s true that many germs, or microbes, can cause serious problems, like infection and illness. But they’re not all bad.

In fact, your body is host to trillions of microbes, from your scalp to your toes and everywhere in between. No amount of hand sanitizer could get rid of them all — and you wouldn’t to. These little bugs, collectively known as your microbiome, actually help your body in a lot of ways. Some scientists even consider the microbiome another organ, because it plays so many key roles in your body.

Your gut in particular is home to a huge microbe population. In recent decades, researchers have found that the gut microbiome is involved in everything from digestive health and weight to mood and immunity.

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What You Eat Impacts Your Gut Microbiome

You have thousands of different species of microbes living in your gut, and some are better for you than others. What you eat has a big influence on which microbes are living in your gut. For example, eating lots of fiber encourages the growth of beneficial bacteria that may help maintain healthy cholesterol and blood sugar levels. These fibers are called “prebiotics.”

You can also add beneficial bacteria to your gut by eating them directly. Fermented foods, like yogurt and sauerkraut, naturally contain microbes that are good for your gut. These are called “probiotics.”

In a recent study, researchers at Stanford School of Medicine had participants eat a diet high in fermented foods for 10 weeks. Looking at blood and stool samples, they discovered that the diet resulted in measurable improvements in microbiome diversity. Participants also had decreases in markers of inflammation suggesting better immunity.

You can learn more about probiotics and prebiotics in The Best Foods for a Healthy Gut.

What Are Fermented Foods?

Microbes can cause food to rot and go bad. But when used in a controlled way, microbes can cause fermentation. Fermentation is a process in which certain microbes “eat” food components, like sugar, and produce other products, like acids, gases, and alcohols.

Yeast is one example: Yeast is a live microbe that eats sugars in flour and produces carbon dioxide, a gas. That’s what causes bread dough to rise.

Fermentation can also increase the acidity of a food, which can block the growth of bad bacteria that would cause food to rot. In that way, fermentation is a way to preserve foods. Sauerkraut, pickles, and kimchi are examples of vegetables that are preserved through fermentation. The whole process gives fermented foods and drinks their unique tastes, aromas, textures, and appearances.

Try These 9 Fermented Foods

Even if the idea of fermented foods is new to you, you’ve probably been eating fermented foods your whole life without realizing it. Here are 9 fermented foods that can help boost your gut microbiome.

One important thing to note: Heat can kill the beneficial microbes in fermented foods. To get the full benefits of these foods, it’s best to eat them raw.

Fermented Food #1: Apple Cider Vinegar

This tangy vinegar is made by fermenting the sugar from apples into acetic acid. There is some research to suggest that using apple cider vinegar can help improve blood sugar numbers which may offer some protection from developing type 2 diabetes. Try it in your salad dressings.

Fermented Food #3: Kombucha

Kombucha is a fizzy drink made by adding certain strains of bacteria and yeast along with sugar to tea, then allowing it to ferment for a week or more. Store-bought kombucha is often flavored with herbs or fruit. Just watch out for sugar numbers: look for a drink with no more than 8 grams of sugar per serving (about 8 ounces).

Fermented Food #3: Kefir

This fermented dairy drink is made using what are known as kefir grains (a combination of bacteria and yeast). The result? A probiotic-laced tangy dairy that’s thinner in consistency than regular yogurt. It’s believed to have an even higher amount of beneficial bacteria than yogurt.

Find it in the dairy aisle alongside yogurt and use it as a base for smoothies or as a swap for buttermilk in pancakes. It’s also good with cereal or granola. Some people also simply drink it as they would milk.

Fermented Food #4: Kimchi

This pickled delight is a Korean staple. Napa cabbage and other vegetables are mixed with a fiery chili-garlic seasoning and left to ferment for several days by lactic acid bacteria. You may be able to find it your regular grocery store these days, or look for it at Asian markets. Use it as a topping for scrambled eggs, burgers, sandwiches, tacos, grain bowls, and stews.

Fermented Food #5: Miso

Miso is a savory paste made from cooked whole soybeans. They’re combined with koji (a bacteria starter), salt and rice or barley, and then left to ferment for some time. The longer the ferment time the darker the color, and the stronger the flavor.

You can make miso soup by dissolving 1-2 tablespoons of miso in warm water and adding bits of tofu, scallion, and mushroom. Miso can add a rich, umami flavor to a variety of dishes. Try whisking it into salad dressings or stir a tablespoon or two into mashed potatoes.

Fermented Food #6: Sauerkraut

Submerged in a salty liquid for several days, cabbage slowly ferments into this crunchy, tangy condiment. To guarantee it still has probiotics, look for the words “unpasteurized” or “raw” on labels. Heat-treated sauerkraut will not have any beneficial microorganisms still present. A couple of forkfuls can instantly jazz up your lunch sandwiches as well as tacos and burgers.

Fermented Food #7: Sourdough bread

Sourdough’s signature tang comes from using a fermented dough. Sourdough doesn’t necessarily contain live microbes — they’re killed off during baking. But some evidence suggests that the fermentation process makes sourdough bread easier to digest for people who are sensitive to gluten. And other research has found that sourdough bread has a lower glycemic index than regular bread. That means it has less of an impact on blood sugar.

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Fermented Food #8: Tempeh

Tempeh is made from whole soybeans that are soaked, cooked, left to ferment. It’s then pressed into a protein- and fiber-rich patty with an earthy, nutty flavor. It has a firm, meaty texture, making it an excellent meat substitute in vegetarian and vegan recipes.

Since you need to cook tempeh, likely, a large amount of the good-for-you probiotics won’t survive the heating process. However, research shows there are other benefits of the fermentation process including making certain vitamins and minerals more available for our bodies to use. You can marinate and grill slabs like you would a steak or crumble and use tempeh as a substitute for ground meat in chili, pasta sauces, and tacos.

Recommended reading: New Foods on the Block: The 5 Superfoods You Have to Try

Fermented Food #9: Yogurt

Yes, even yogurt is a fermented food! It’s made from fermenting milk (or a non-dairy alternative) with a starter culture of bacteria. The bacteria convert the sugars in milk to lactic acid, giving yogurt it’s tangy flavor. Look for yogurt labeled with the “Live & Active Cultures” seal — it guarantees 100 million probiotic cultures per gram at manufacturing time.

A Note of Caution

If you’re not used to eating fermented foods, you may experience some gas and bloating when you start eating them. Introduce new fermented foods slowly to avoid these side effects.

Also, some fermented foods like miso and sauerkraut are high in sodium. Use these sparingly if you’re watching your sodium intake.

See our sources:
Gut microbiome and mood: Nutritional Neuroscience
Influence of diet on the gut microbiome: Journal of Translational Medicine
Prebiotics and the gut microbiome: Harvard School of Public Health
Study on fermented foods and the gut microbiome: Cell
Apple cider vinegar and blood sugar: BMC Complementary Medicine and Therapies
Fermentation improves nutrient availability: Fermentation

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