Get full access to Outside Learn, our online education hub featuring in-depth yoga, fitness, & nutrition courses, when you sign up for Outside+.
The key to better digestive health: fostering the right environment for good gut bacteria. Flavorful fermented foods are just the tasty ticket.
If you regularly reach for probiotic-rich drinks and foods like kefir, kombucha, yogurt, and kimchi, you probably do so knowing that each is teeming with “good” bacteria that are beneficial to digestive health. But a healthy, happy gut is just one of the many great things you gain. Experts are now learning that consuming foods that cultivate more of the favorable bacteria, such as Lactobacillus acidophilus, within your gut microbiota—the colony of bacteria deep within your gastrointestinal system—has multiple, far-reaching health benefits.
“These helpful bacteria directly communicate with our immune systems, our metabolism, and even our central nervous system and brain,” says The Good Gut co-author Erica D. Sonnenburg, PhD, and senior research scientist in the Department of Microbiology and Immunology at Stanford University School of Medicine. How bacteria communicate isn’t yet fully clear, but one known important step is that they release chemicals into the gut which then enter the bloodstream and bind to receptors in our tissues, changing the activity of those cells, says Sonnenburg. The beneficial bugs also nourish the lining of our digestive tract so that it functions optimally, selectively allowing the absorption of vital nutrients while keeping toxins from escaping into other parts of our body. So it should come as no surprise that when the “bad” bacteria, such as C. difficile, outnumber the “good,” the result is an increasing number of health concerns, including inflammation, weakened immune function, depression, diabetes, colon cancer, heart disease, allergies, poor digestive health, and possibly even weight gain.
Get the recipe: Veggie Ramen (shown above)
Unfortunately, the conveniences of modern life make it difficult to keep a good balance of gut bacteria. Our squeaky-clean homes and the antibiotics we take when we’re sick wipe out the good bacteria along with the bad. And the common Western diet of overly processed foods deprives us of the raw nutrients that help healthful bacteria thrive. The result? The diversity of our microbiota is shrinking, leaving us harboring fewer species than our parents and ancestors.
“Optimal health is associated with high diversity of gut bacteria, whereas illness of all types is associated with loss of diversity,” says Leo Galland, MD, co-author of The Allergy Solution.
The good news: You may be able to reverse the trend. Research suggests that eating the right foods—and avoiding the wrong ones—can significantly improve the microbial balance in your gut in as little as one day, according to a 2013 Harvard University study. And considering that bacterial cells in your gut make up more than half the cells in your body, it’s crucial to feed them correctly. To get started, follow our three-pronged plan for cultivating a better bacterial profile. Then try the delicious recipes from Mara King, co-owner of Ozuké, a fermented-foods company in Boulder, Colorado. All four dishes are packed with gut-friendly ingredients to help you feel your best this fall.
“People tend to be scared of fermentation because we’re trained to fear bacteria,” King says. “But I like to think of fermenting as tending to an indoor garden that will keep you happy and healthy.”
Get the recipe: Kraut Cakes with Yogurt Dipping Sauce
Step 1: Fuel up on fermented foods
One of the easiest ways to better your microbial mix is to load up on fermented foods. Fermentation is an age-old practice that uses bacteria or yeast in the preparation of foods and drinks like yogurt, kombucha, kimchi, and sauerkraut. In addition to supplying you with more helpful microbes, the process of fermentation actually breaks down food, liberating key nutrients like B vitamins, vitamin C, iron, and antioxidants that your body can then more easily access. The bacteria used to produce fermented foods also crowd out harmful gut microbes and steal their nourishment, so the bad bugs are less likely to thrive. But keep in mind that each strain of probiotic is unique, providing its own distinct health benefits. So, for instance, while Lactobacillus reuteri DSM 17938 might keep your digestive system regular, it won’t help to soothe eczema—but Lactobacillus salivarius LSo1 will. Since research still hasn’t uncovered which strains are contained in each fermented food, your best bet is to eat a wide variety of them, especially those that you prep at home, as the number of microbes in store-bought foods tends to dwindle the longer they sit on store shelves.
Get the recipe: Gado-Gado Salad with Kimchi-Nut Dressing
Step 2: Feed your good bacteria
Gut bacteria love to feast on prebiotics, a special class of carbohydrates that our bodies can’t fully break down. Because we can’t digest them well, some of these carbs travel intact to the large intestine, where good gut bacteria ferment them and use them for food. This process produces a magical byproduct: tiny nutrients that are known as short-chain fatty acids, or SCFA. These compounds nourish the cells that line your colon, as well as the other favorable bacteria that live there. Prebiotics are like a fertilizer that can help healthy gut bacteria grow and multiply, says Rob Knight, PhD, a professor in the Department of Pediatrics at the University of California, San Diego. The hard-working SCFA may also help decrease inflammation and enhance immune health.
Yet, when it comes to prebiotics, we don’t consume nearly enough. So aim to regularly include more naturally rich sources like asparagus, fennel, garlic, leeks, lentils, onions, peas, pomegranates, nectarines, and watermelon. One particularly helpful prebiotic is resistant starch, found in bananas, beans, pasta, potatoes, and rice. In addition to helping you grow more good gut bacteria, resistant starch helps your intestine absorb calcium more efficiently, improves your body’s ability to use glucose, and may help you burn fat more effectively. Like other prebiotics, resistant starch escapes full digestion and travels to the colon where it produces SCFA. Factors such as ripeness, temperature, and cooking methods alter the digestibility of resistant-starch granules. For example, while warm pasta and potatoes contain small amounts of resistant starch, cooling these foods after cooking—as with a cold pasta or potato salad—actually increases resistant starch. A banana’s resistant starch can range anywhere from a third of a gram in a ripe banana to more than six grams in a green one, so it’s better to eat your bananas before they’re fully ripe.
Get the recipe: Kimchi Jjigae
Step 3: Avoid foods that harm good bacteria
Finally, to build a better microbiota, limit foods that sabotage it—namely those high in sugar, refined carbohydrates, and unhealthy processed fats. “These types of meals devastate the diversity of our gut microbes because they’re deficient in the fiber that helps cultivate a diverse microbiome,” says Galland. “Plus, processed fats and sugar act as food for the unfavorable bacteria and encourage their growth.”
ABOUT OUR EXPERT
Karen Ansel, MS, RDN, is a nutritionist, author, and freelance writer based in Syosset, New York. Mara King is co-founder of Ozuké, a probiotic pickling company based in Colorado.