Do Fermented Foods Live Up To The Hype? Here’s What The Research Says

Trendy products like kombucha and tempeh are growing in popularity, and there's a good reason for that.

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Health food stores tout kimchi, kefir, and kombucha as gut-aiding superfoods, but is the hype true?

Proponents say that fermented foods increase good bacteria in the gut, which improves digestion, immunity, and a host of other biological processes.

Skeptics, however, warn that good bacteria can’t survive the acidic conditions of the stomach, which renders any potential benefits null and void.

So who’s right, and what exactly is fermentation anyway?

Fermentation relies on the presence of microorganisms to convert sugar to alcohol or acid.

This process results in high concentrations of good bacteria, like Lactobacilli, which have a large number of health benefits. While many of these probiotics can be taken in supplement form, research suggests that naturally fermented foods may be more beneficial.

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Like so many current fads—think raising chickens or eating organic food—fermentation is an ancient practice. In fact, there is evidence that Neolithic villagers made a fermented beverage of rice, honey, and fruit over 9,000 years ago.

Since then, cultures around the world have concocted yogurt, sauerkraut, pickled cucumbers, tempeh, soy sauce, and dozens more fermented foods, beverages, and condiments.

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While the original goal of fermentation was a longer shelf life, cultures that incorporate fermented foods in their everyday diets also benefit from longer lives on average.

Fermentation has proven health benefits, but they don’t always outweigh the impact of harmful ingredients.

Various studies have touted the positive effects of eating fermented food—ranging from better mental health to clearer skin. The trick is to make sure you’re not consuming unhealthy amounts of sugar or sodium as a result of eating fermented food.


Certain fermented foods, particularly kefir and yogurt, can have staggering amounts of sugar in them. To make matters worse, some manufacturers heat treat yogurt after the fermentation process. This is done to kill any bad bacteria, but it destroys the good bacteria, too.

Many fermented food claims would benefit from more research, but what we know now is promising.

Because of the wide variety of fermented foods available, many of them remain unstudied. Still, the ones that have been researched show great promise for increasing our gut biodiversity. For instance, a study of Greek dry salami found 348 different strains of lactic acid bacteria present in the food.


Kimchi, a fermented cabbage dish, boasts an impressive list of benefits including anti-cancer, anti-obesity, and anti-aging properties. If you want more proof that this Korean side dish is a superfood, scholarly research indicates that the average life expectancy of South Korean women will likely surpass 90 years by 2030.

Other foods that have health-boosting live cultures include pickles and sauerkraut. Just be sure to pick these foods from the refrigerated section of the store. Jarred pickles and canned sauerkraut from the shelves do not have live cultures in them.

That’s right: Any foods that have been pasteurized to ensure a longer shelf life do not contain good or bad bacteria.

Probiotics can survive the gastrointestinal (GI) tract, but they could use your help.

Skeptics of probiotics and fermented food believe that acid in the stomach kills off the good bacteria before it can reach the lower GI tract. Testing this hypothesis is difficult, but multiple studies have confirmed that good bacteria can survive and have a positive impact on our gut flora.


Choosing fermented foods with resilient strains of good bacteria, such as B. animalis, L. casei, L. rhamnosus, and L. plantarum, helps ensure that the probiotics will survive long enough to affect your gut biome.

Researchers have studied fecal samples to prove that good bacteria can survive the journey through the GI tract. Though there was variation, some strains were found in the back-end samples, proving they were able to withstand the entire digestive process. Probiotics from yogurt fared better than probiotics in cheese, for instance.


Researchers will continue studying the health benefits of probiotics, but for now, there is clear evidence that fermented food benefits your gut.

Bottom line: Choosing refrigerated foods with live cultures is essential, and opting for items with no added sugar or salt is also a good rule of thumb.