For many years, humans have known that bacteria and other microorganisms are capable of transforming food substrates, making them both tasty and nutritious. More and more, chefs and other food-makers are putting bacteria to work to produce fermented foods. With delicious results.

Besides flavour, though, are there other reasons to seek out fermented foods? Scientists around the world are trying to answer this question by studying the possible health benefits of consuming live cultures.

Robert (Bob) Hutkins, Professor of Food Science at the University of Nebraska-Lincoln (USA), studies bacteria in fermented foods and factors that affect their survival in the gastrointestinal tract. In untangling the health benefits we can attribute to fermented foods, he says, it’s important to address the common misconception that fermented foods are the same thing as “probiotics”—the latter being live bacteria that confer health benefits when consumed in adequate numbers, according to the definition set by an international panel of experts in both 2001 and 2014.

“Not all fermented foods contain live organisms,” Hutkins tells GMFH editors. “Beer and wine, for example, undergo steps that remove the organisms [like yeasts that allow fermentation]. Other fermented foods are heat-treated and the organisms are inactivated. Bread is baked and sauerkraut is often canned. So while these foods may be nutritious, they do not have probiotic activity.”

He continues, “That being said, there are still lots of fermented foods that do contain live organisms, including yogurt and other [fermented] dairy foods, most cheeses, non-heated sauerkraut and kimchi, even many of the European-style dry fermented sausages.”

So then, can the term probiotic be applied to the subset of fermented foods that do contain live microorganisms when consumed? Hutkins says it cannot: “The live organisms present in these products are there for one main reason – to perform the fermentation (i.e., convert milk into yogurt or cheese, or cabbage into kimchi). These cultures do not necessarily have any probiotic functions. By definition, probiotics must ‘confer a health benefit’. That means the probiotic must have been characterized and have clinical evidence of a health benefit. Cultures are not probiotic unless they have met this requirement.”

So not all fermented foods qualify as probiotic, and not all probiotics take the form of fermented foods. But Hutkins says an item can occasionally be both a probiotic and a fermented food: “Sometimes the organism responsible for carrying out the fermentation are also known to have probiotic functions (i.e., they do double-duty). Many yogurt cultures, for example, have probiotic activity.”

An ongoing area of investigation for food scientists is whether the method of delivering live microorganisms, otherwise known as the ‘food matrix’, matters for how the bacteria survive—and for how they contribute to health.

“The matrix can affect viability and survival of the organism, such that some foods may be more-or-less hospitable than others,” explains Hutkins.

“Probiotics have long been added to dairy products, but now they are incorporated into fruit and vegetable smoothies, nutrition bars, even chocolates,” he continues. “At this point it is not possible to generalize about how well the organism will manage in each of these; they have to be analyzed on a case-by-case basis. Still, dairy foods have long been the main delivery vehicle, and most probiotics do just fine in this matrix.”

Hutkins predicts the array of fermented foods in the average grocery store will only continue to grow in the years ahead. “Fermented foods are one of the hottest categories in the grocery,” he notes. “It’s not just the yogurt section that has quadrupled. At many grocery stores, one can now find kimchi, miso, and dry fermented sausages. Many have olive bars. Of course, micro-brewed beers and boutique wines and distilleries are everywhere.”

Not only that, he says, “The scientific community is all over the diet/gut microbiota/human health connection. Fermented foods contribute a diverse array of microorganisms to the existing gut microbiota and thus have the potential to affect health.”

Hutkins’ day job is the scientific study of fermented foods, but his fondness for them persists after hours, too. “In my fridge, you can find kimchi, olives, miso, Parmesan cheese, kefir, and yogurt,” he says. “Love the balsamic vinegar, sourdough bread, and of course red wine, for heart health purposes!”

See Hutkins explain the potential health benefits of fermented foods in this video.

Kristina Campbell
Kristina Campbell
Science writer Kristina Campbell (M.Sc.), from British Columbia (Canada), specializes in communicating about the gut microbiota, digestive health, and nutrition. Author of the best selling Well-Fed Microbiome Cookbook, her freelance work has appeared in publications around the world. Kristina joined the Gut Microbiota for Health publishing team in 2014.  Find her on: GoogleTwitter