Are fermented foods up to the hype?  - Harvard Health

Are fermented foods up to the hype? – Harvard Health

Stores are full of fermented products containing probiotics. Here’s how they can improve health – and how they can fail.

overhead shot of a bowl of sourdough on a counter with a recipe written on a card next to it

Walk through the refrigerated aisle of a supermarket these days and you’ll notice shelves full of fermented foods and drinks. New additions such as milk-based kefir, kimchi (Korean cabbage), kombucha (tea) and tempeh (soy) joined perennial favorites such as yogurt, sauerkraut and beer, highlighting a market that is expected to grow by $533 million globally over the next four years.

But the newfound popularity of fermented foods belies a legacy dating back thousands of years. Ancient civilizations used fermentation, which incorporates bacteria and yeast to break down sugars and carbohydrates, transform flavors and prevent spoilage. Scientists have long 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 that mean you have to fill your basket with fermented foods and drinks? Only if you’re realistic about what you’re buying, says a Harvard expert. Heat and bright lighting used in commercial food manufacturing can kill probiotics advertised on product labels.

“Nothing on the label tells us that,” says Nancy Oliveira, registered dietitian and head of nutrition and wellness at Harvard-affiliated Brigham and Women’s Hospital. “In reality, there may not be as many probiotics or microbes in fermented foods as there were in the first place. You buy them thinking they’re so good for you, but they may not be. able to provide all the expected health benefits.”

Range of health benefits

That said, eating and drinking even small amounts of probiotics over time can benefit our health, Oliveira says. A 2021 study in the journal Cell adds to the research pointing out the benefits. The analysis suggests that diets high in fermented foods increase the variety of gut bacteria and reduce markers of inflammation better than a diet high in fiber.

But high-fiber foods like fruits, vegetables and whole grains are definitely part of the power of probiotics, Oliveira says. Dubbed “prebiotics,” these foods fuel the growth of different types of gut bacteria and work hand-in-hand with fermented foods to promote these effects:

Soft 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 found in fermented foods can also help digest other foods you eat.

Dampen inflammation. Probiotics boost the proper functioning of the immune system and may reduce the risk of inflammatory diseases such as heart disease, diabetes and cancer, says Oliveira.

Stimulates nutrient absorption. Fermented products can deactivate substances in other foods called “antinutrients”, which can inhibit the absorption of essential nutrients such as iron, zinc and B vitamins12 and K.

Fight bad bacteria. Beneficial bacteria lower the pH of your gut and produce germ-fighting proteins. Both can suppress the growth of harmful bacteria.

Benefits of Sourdough Belly

Billions of people around the world eat some kind of bread every day. But sourdough leapfrogged its competitors as the pandemic crumbled in 2020. Social media was teeming with heartwarming images of homebound bakers churning out mouth-watering loaves in a stomach-churning era.

Indeed, stress-induced stomach issues have prompted many people to try sourdough during the global health crisis, says Nancy Oliveira, head of nutrition and wellness at Brigham and Women’s Hospital. Fermented using a “starter” that typically contains lactic acid bacteria and yeast, sourdough has long been a favorite of those interested in so-called low-bloat foods that are more easily digested and “easier to digest,” explains Oliveira.

Aside from its distinctive “sour” taste and chewy texture, how does sourdough differ from whole grain breads? Its fermentation process can reduce compounds called “anti-nutrients” found in some whole grains, improving nutrient absorption and fueling digestion. Oliveira adds that sourdough also contains antioxidants – which may reduce the risk of certain diseases – and a lower glycemic index than white bread, which means it can minimize blood sugar spikes.

Buying tips

If you’re able to ferment your own foods, such as pickles, sauerkraut or sourdough bread, it can preserve all of the beneficial bacteria that commercial manufacturing might destroy, Oliveira says. Otherwise, here are some strategies for getting the biggest probiotic punch from store-bought versions.

Look for living cultures. The words “live and active cultures” may appear on the label (like in yogurt), or you may see bubbles in liquids (like kombucha, although sometimes added carbon dioxide produces the fizz). These signs mean that the product probably contains probiotics.

Make sure they are refrigerated. Shelf stable products labeled as “fermented” are usually pickled using vinegar, not live organisms, and do not contain probiotics.

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