August 31, 2021 10:30:57 pm
Written by Tara Parker-Pope and Anahad O’Connor
I was fascinated by a recent story about fermented foods by my colleague Anahad O’Connor. The story explains the science of how six servings a day of fermented foods can lower inflammation and improve the diversity of your gut microbiome, which may lower your risk of chronic disease. But I wanted to know how to put the advice into practice. I asked Anahad, the smartest food science reporter I know, for more details. Here’s our conversation:
Q: Can you explain a little about what fermentation is?
A: To put it simply, fermentation occurs when microorganisms like bacteria, yeast and mould convert the starches and sugars in food into alcohol, lactic acid, carbon dioxide and other compounds. Known as probiotics, these live microorganisms that are found in fermented foods can produce vitamins, and other healthful nutrients as well. Probiotic-rich foods have long been considered beneficial for gut health, and the latest study that I wrote about suggests that they may also reduce inflammation.
Q: Where can I find a list of fermented foods? Should I just eat those used in this study?
A: There are probably thousands of different types of fermented foods consumed around the world. But the authors of the new study focused on five in particular: yogurt, kimchi, sauerkraut, kombucha and kefir. These foods are chock-full of live microorganisms, and they are widely available at grocery stores, supermarkets and farmers’ markets.
You can find a wide variety of other fermented foods as well, like miso, cottage cheese, Gouda cheese and some types of apple cider vinegar. People who took part in the new study also consumed a lot of probiotic-containing “gut shots,” which are small bottles of fermented beverages, usually about 2 ounces in size, sold in many grocery stores. Or if you are the adventurous type, you could also make your own fermented foods at home.
Q: How should I shop for fermented foods?
A: Not all foods that are made through fermentation contain live microorganisms when they reach store shelves or your kitchen table. The dough that is used to make sourdough bread, for example, is fermented by bacteria (hence the sour flavor), but the microbes are destroyed during baking. Wine is made by fermenting grape juice. But commercial wines are filtered and processed to get rid of most of the live microbes.
Dr. Justin Sonnenburg, a Stanford University microbiologist who was a co-author of the new study, said that to ensure the fermented foods you are buying actually contain probiotics, read the packaging and look for statements like “contains probiotics” or “contains live cultures.” Some packages might simply say “naturally fermented.” And some foods, like yogurt and kefir, will often list the probiotic strains that they contain on their label. You will typically find these fermented foods in refrigerated aisles at grocery stores.
Q: Kimchi is too spicy for me. Is the spicy sauce part of the benefit?
A: According to Sonnenburg, kimchi is exceptional because it’s relatively complex for a fermented food. “It has a lot of ingredients, and in some cases it even includes fish sauce or soy sauce, which are also fermented foods.” It’s possible that some of the spices in kimchi confer health benefits, he added. But the benefits seen in the new study were likely a result of more than just the spicy component of kimchi.
Most fermented foods contain fewer ingredients than kimchi, and it’s easy to find ones that are not spicy at all, including yogurt, kefir, kombucha and sauerkraut. But there are many recipes for kimchi, and you might be able to find some online that are on the milder side, said Christopher Gardner, a co-author of the new study and director of nutrition studies at the Stanford Prevention Research Center.
Q: There are so many different kinds of yogurt with varying levels of sugar and processing. Is all yogurt created equal? What should I look for?
A: The starter cultures used to make yogurt are pretty standardized. But often manufacturers will add additional probiotic strains. Every yogurt manufacturer uses its own mixture of probiotics. The key is to look on the label for statements like “contains live and active cultures.”
But Sonnenburg stressed that you should be careful not to buy flavored yogurts that contain a lot of added sugar. “Most yogurts are probably fairly equivalent except for the yogurts that contain as much sugar as soda,” he said. “At that point, the huge amount of sugar they contain is probably more than negating any positive effects from the fermented foods.”
Kombucha, a type of fermented tea, is another food that can contain a lot of added sugar, which manufacturers often add to the drink before they bottle it to mask its sour flavors. Some brands of kombucha are also pasteurized, which destroys their probiotics. Look for brands that are low in added sugar and that say things like “contains live organisms” on the label.
Q: Did the people in the study feel any different after trying fermented foods? Or was the difference seen only in the microbiome data?
A: A lot of the participants enjoyed adding the fermented foods to their diets and continued eating them after the study ended. In general, though, they did not report feeling any different when they were surveyed about things like fatigue, focus and their overall quality of life during the study, said Dalia Perelman, a co-author of the study and a research dietitian at Stanford. A few of the participants did say that they had fewer cravings for sweets during the study, but that was anecdotal, she added.
Q: Has this study changed your eating habits?
A: Yes, definitely. I’ve always tried to include fermented foods in my diet because I had reason to believe they were good for your health based on what we know about probiotics. Plus, these foods tend to have other health properties as well: Sauerkraut and kimchi are made from vegetables, which are generally good for you, and yogurt is an excellent source of protein.
Yogurt is one of my favorite foods: I eat it daily. But now I’m also including sauerkraut and other fermented foods in my diet on a regular basis as well, which I’ve found easy to do. I keep a jar of sauerkraut in my fridge, for example, and I take a few bites at lunch or dinner. When I make a salad for lunch, I top it with olive oil and a brand of apple cider vinegar that is unpasteurised and unfiltered, and it contains the “mother,” the substance that contains the friendly bacteria, which gives some apple cider vinegars their murky appearance.
So, I’d say that on a daily basis, I now eat two or three types of fermented foods. I enjoy eating them, they’re easy to find and include in my diet, and the evidence suggests that they’re likely to be good for your health. So, at the very least, I don’t see any downside to eating them.
This article originally appeared in The New York Times.
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