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Cold potatoes—that is, taters that have been washed, cooked, and cooled—are one of the best sources of resistant starch. Resistant starch is a prebiotic, a type of indigestible carbohydrate that acts like food for gut bacteria, encouraging the good bugs to grow and flourish. While resistant starch has many health benefits, one of its most promising aspects is its ability to increase insulin sensitivity, helping people reduce diabetes risk and even lose weight.
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Think of kefir as yogurt's tangier but more powerful cousin. The drink is made by seeding milk with kefir "grains," which are tiny bundles of yeast and bacteria, and letting it sit. Over time the grains ferment the milk, producing a tart drink full of probiotics, or healthy bacteria. A 2013 study found that kefir can help relieve gastrointestinal problems and allergies and may even have a positive effect on heart health. One caveat however: Many commercial kefir drinks contain very high amounts of added sugar, which feeds bad bacteria in your gut, so make sure you read the label and ingredient list. These are sneaky signs you might be eating too much sugar.
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Most people go out of their way to avoid green bananas but there's good news for people who just can't wait until they're fully ripe. Green bananas are a rich source of prebiotics, particularly resistant starch. They also have a healthy dose of both soluble and insoluble fiber, vitamins, and minerals. The combo provides a feast for good gut bacteria and helps protect your heart and bones. Can’t get past the taste? Try them boiled or fried or sub some green banana flour in place of regular flour. Here's how sniffing bananas could help you lose weight.
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Don’t let the name throw you—this Korean dish is not only tasty but a health superstar. Kimchi is made by fermenting vegetables with probiotic lactic acid bacteria, which gives it the same boost of healthy bacteria as other fermented foods, like yogurt. Plus, since it’s made from cruciferous veggies like bok choy and cabbage along with healthy spices like garlic and peppers, it provides a mega dose of vitamins, fiber, and antioxidants. One study found that kimchi helps protect against cancer, obesity, and constipation while lowering cholesterol, boosting brain and immune function, and even providing some anti-aging benefits. Here are other proven cancer-fighting foods.
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Sauerkraut is kimchi’s German cousin, a lacto-fermented brine filled with cabbage, carrots, and spices—not to mention plenty of healthy bacteria for your gut. And not only does it have similar benefits as other fermented veggies but a study done by William & Mary college found that eating a daily serving of sauerkraut helped significantly reduce social anxiety. The researchers believe it’s because more than 80 percent of the calming hormone, serotonin, is manufactured in our guts (not our brains!) and the good bacteria boosted serotonin production.
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Yes, it's true! Chocolate can help encourage the growth of healthy gut bacteria. A study published in the International Journal of Food Biology found that combining chocolate with probiotics magnified the benefits of both. The chocolate protected the bacteria as it passed through the stomach, making sure it was absorbed in the small intestine while the bacteria helped the body properly digest the chocolate, enabling it to extract all the micronutrients and antioxidants. Talk about a win/win! Here are more healthy reasons to eat chocolate.
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Everyone’s favorite way to get bad breath also has powerful gut bacteria-boosting properties. Garlic is not only Americans’ number-one favorite spice (after salt) but is also beloved by bacteria thanks to its rich supply of prebiotics, their preferred food. Raw garlic is the best source but for those who don’t like the burn (or who feel like kissing someone later); cooked garlic also works well—so well in fact that a study published in Food Science and Human Wellness found that eating it is an effective way to prevent many gastrointestinal illnesses. Here are more surprising benefits of garlic. Feeling motivated? Try these seven other foods that also boost gut health.