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Fermenting foods can extend their shelf life. But can eating fermented foods do the same for people?

It's a question investigators have been digging into for years, with interest growing over the past decade. As the slightly sour-tasting foods and beverages have risen in popularity, researchers have focused a lot of their attention on kimchi, a staple of the Korean diet.

The dish gained global recognition in 2013 when UNESCO put kimjang – the culture of making and sharing kimchi – on its . It reached even greater popularity during the COVID-19 pandemic, riding a wave of Korean popular culture driven by K-pop and K-dramas.

Kimchi is believed to have medicinal properties that align with the Korean philosophy of yak sik dong won – food is medicine. A 2023 , published in the Journal of Ethnic Foods, backs that up. Kimchi has been shown to fight inflammation, prevent colon cancer, reduce cholesterol and blood glucose, strengthen the immune system and prevent atherosclerosis, the buildup of plaque in the arteries. It has also been shown to reduce body fat and contains probiotics, which increase healthy bacteria in the gut.

"Not only does it help with digestion, it also has a distinct flavor filled with funkiness," said Tessa Nguyen, a Detroit-based chef and dietitian.

So what exactly is kimchi?

Consumed as a side dish, kimchi has been part of Korean food culture for thousands of years. It is made by fermenting vegetables and other seasonings – such as garlic, ginger and red chili powder – in a closed container at low temperatures.

There are more than 200 varieties of kimchi. The most well-known is called baechu, which is made from napa cabbage. Other popular forms of kimchi are made from radishes, green onions and mustard greens.

"People think of the cabbage variation, but kimchi can be made from any fermented vegetable," said Nguyen, whose favorite type of kimchi – oi sobagi – is made from cucumbers. "It's salty, sour and has a flavor pop. You taste the chili powder, onions and garlic and the sourness that is reminiscent of vinegar."

The nutritional value of kimchi can vary. A 150-gram cup of kimchi made with cabbage, for instance, can contain 22.5 calories, less than a gram of fat and 2.4 g of fiber.

However, the serving comes with 747 milligrams of sodium. Excessive sodium in your diet can lead to high blood pressure, a major risk factor for cardiovascular disease. suggest a maximum of 2,300 mg of sodium daily for most adults, and the ·¬ÇÑÊÓƵ says the ideal limit is 1,500 mg, especially for people with high blood pressure.

Nguyen is of Vietnamese and Polish descent, but she lived in South Korea from 2018 to 2022, where she taught English to young people. She often swaps kimchi recipes with her Korean friends.

Every year, she looks forward to celebrating kimjang, when people gather following a fall harvest to make huge batches of kimchi that ferment for a month or more.

For the cabbage variety of kimchi, soak it in a brine of salt water overnight so the leaves get wilted and flexible, Nguyen said. Then spread the ginger, garlic and chili paste on each leaf. "It takes a long time," she said. "You put it into clay vessels called onggi and let it ferment. You can age it for different lengths of time, like cheese."

If not eaten fresh, kimchi should be stored in the refrigerator and eaten within a week. While it can be fermented longer, this changes the taste and texture. It should be discarded if mold appears.

Nguyen loves kimchi so much that she takes it with her when she travels. "I want to make sure I'm not missing my home foods," she said. "I just have to wrap it well so it doesn't spoil."

Eat It or Leave It? is an ·¬ÇÑÊÓƵ News series that takes a closer look at the health benefits and drawbacks of specific foods, drinks and nutrients.