Do fermented foods live up to the hype?

The fresh popularity of fermented foods belies a heritage dating thousands of years. Ancient civilizations used fermentation, which incorporates bacteria and yeast to break down sugars and carbohydrates, to transform flavors, and prevent spoilage.

Scientists have long since learned that fermented foods also contain live microorganisms called probiotics, which bolster a healthier mix of the trillions of "good" bacteria that live in our gut.

Does this mean you should load up your shopping cart with fermented foods and drinks? Only if you’re realistic about what you’re buying, a Harvard expert says. Heat and bright lighting used in commercial food manufacturing can kill off the very probiotics advertised on product labels.

"Nothing on the label tells us that," says Nancy Oliveira, a registered dietitian and manager of the Nutrition and Wellness Service at Harvard-affiliated Brigham and Women’s Hospital. "In reality, there may not be as many probiotics or microbes left in fermented foods as they started with. You buy them believing they’re so good for you, but they may not be able to provide all of the intended health benefits."

Array of health benefits

That said, eating and drinking even small amounts of probiotics over time can support our health, Oliveira says. A 2021 study in the journal Cell adds to research underscoring the advantages. The analysis suggests diets rich in fermented foods increase gut bacteria variety and lower inflammation markers better than a high-fiber diet.

But high-fiber foods such as fruits, vegetables, and whole grains certainly figure into the power of probiotics, Oliveira says. Dubbed "prebiotics," these foods fuel the growth of different types of intestinal bacteria and work hand in hand with fermented foods to promote these effects:

Smooth digestion. The fermentation process has already broken down some natural sugars and starches, so your digestive tract doesn’t have to work as hard. The "good" bacteria in fermented products can also help digest other foods you eat.

Dampen inflammation. Probiotics stimulate proper immune system function and may lower the risks of inflammation-driven conditions such as heart disease, diabetes, and cancer, Oliveira says.

Boost nutrient absorption. Fermented products may deactivate substances in other foods dubbed "antinutrients," which can inhibit the absorption of essential nutrients such as iron, zinc, and vitamins B12 and K.

Battle bad bacteria. Beneficial bacteria lower your intestine’s pH levels and produce germ-fighting proteins. Both can quell the overgrowth of harmful bacteria.

Harvard Health Publishing

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