Myth vs. Fact: Fermented Foods

Fermentation is one of the world’s oldest food preservation techniques, but it’s predicted to be the next big thing in 2023. What’s old is new again.

Fermented foods topped the list of “superfoods” that registered dietitians predict consumers will seek out in 2023, according to a national survey by Today’s Dietitian and Pollock Communications.

From a culinary perspective, fermentation dominates 2023 food trend lists. Chefs are embracing umami-packed fermented ingredients, including miso, natto, gochujang and koji – the latest darling on the fermentation scene. Hailed as Japan’s national mold, koji is a made with fermented rice, barley and soybeans.

Chefs and mixologists are also experimenting with fermented fruits, such as fermented berries, pineapple, melons and ume, a pickled sour Japanese plum. Fermented fruits, juices and syrups are infusing vinaigrettes and cocktails on restaurant menus, along with drinking vinegars or shrubs.

Fermentation has long been used to make beverages – it’s the process that helps to turn grapes into wine and creates the alcohol in beer. Now there’s an entirely new crop of fermented beverages beyond kombucha – from kefir water or tibicos to beet kvass and the fermented Mexican pineapple drink tepache.

Once a sleepy ingredient reserved for an occasional hot dog or Rueben sandwich, sauerkraut has also emerged as a superstar ingredient due to the fermentation halo. Now you can find all sorts of refrigerated pouches of flavored kraut, “gut shots” of sauerkraut brine and even chips made with sauerkraut.

Home cooks are also getting in on the fermentation trend. A search on Amazon revealed over 5,000 books on fermentation, including “The Noma Guide to Fermentation” from the world-famous restaurant in Copenhagen that’s known for its funky fermentations. To get started, you can buy fermentation vegetable kits and take a class or join a club for home fermenters.

SPINS, a wellness focused data technology company, reveals that yogurt and kombucha dominate sales, yet other fermented foods and beverages are experiencing tremendous growth, especially refrigerated sweet pickles (23%), kimchi (22%), refrigerated pickled tomatoes (20%), refrigerated kvass (70%) and hard cider (15%).

The trend seems to check off several boxes: intensely flavored, functional, artisanal, handcrafted, heritage, global and sustainable.

Despite the rapid rise of fermentation, the growing popularity has led to misinformation. In fact, The Fermentation Association was created to help bring scientific clarity to the growing category of fermented foods.

“Many consumers are confused about fermentation,” says Amelia Nielson-Stowell, editor at The Fermentation Association. “They know it’s good for them, but they don’t understand why or what products are fermented.”

Consumer education is a big part of the association’s mission, along with helping to advance the scientific support for fermented foods.

The confusion and misperceptions are also the reason the International Scientific Association for Probiotics and Prebiotics (ISAPP) convened a group of scientists to propose the first official definition of fermented foods: “Foods made through desired microbial growth and enzymatic conversions of food components.”

What exactly does that mean? Fermented foods use microorganisms (also known as microbes) in processing, such as lactic acid bacteria for making yogurt and cheese, sauerkraut, kimchi, sourdough bread and salami. Other fermentation microorganisms are fungi, especially yeasts used for baking, brewing and wine-making. Within the fungi category are molds that are used in fermented meats and cheese, soy sauce, miso and tempeh.

Fermentation itself seems rather simple. So what’s the confusion? Fermented foods are sometimes mistakenly referred to as probiotics. Even though the terms are often used interchangeably, that’s inaccurate, says Mary Ellen Sanders, executive science officer for ISAPP and co-author of the proposed definition of fermented foods.

Apart from yogurts and certain cultured milks like kefir, few fermented foods actually contain probiotics. Yet fermented products often boast about probiotics on package labels, especially brands of kombucha, pickles, olives, sauerkraut and other fermented vegetables.

While the FDA may not be regulating the use of the term “probiotic” on product labels, the word is scientifically defined by ISAPP and the World Health Organization. Fermented foods rarely live up to the definition – even if you see “live and active cultures” on the label.

That’s not to say fermented foods aren’t beneficial, and there are many reasons to enjoy them. Here’s what you should know when evaluating and purchasing fermented foods.

Not all fermented foods and beverages contain probiotics.

To qualify as a probiotic, a health benefit in humans must be demonstrated by scientific research. There also needs to be evidence that this specific strain of good bacteria at a defined level will reach the gut alive. Fermented foods may contain live microbes, but they lack specificity of the strain, usually at variable levels, and a potential health benefit has not been clinically documented.

The widespread use of “probiotic” on labels of fermented foods that do not qualify is misleading, says Sanders, who believes the word is being commoditized.

Instead, she recommends companies stick with descriptors such as “contains live and active cultures” or “fermented with live cultures” without erroneously claiming to be a probiotic.

“If ‘probiotic’ is used to mean ‘fermented food’ it loses its utility as a term,” she says. “Its importance is that it is tied to demonstrated health benefits. If it’s misused to mean anything containing a live culture, the term loses its clout.”

Just as there are laws for standards of food identity, scientists believe we should strive to do the same when describing microbes in fermented foods.

Even if fermented foods contain “live cultures,” this does not make them a probiotic. The starter cultures used for fermented foods are selected based on performance traits, not health benefits, says Robert Hutkins, professor of food science at the University of Nebraska-Lincoln and a board member of the Fermentation Association.

That means they’re needed to kick-start the fermentation process – providing the distinctive sour flavor profile or other attributes like texture, digestibility or extended shelf life. The microbes are rarely one of the defined strains that meet the qualifications of a probiotic or have the required scientific evidence demonstrating a health benefit.

Even so, it’s common to see articles inaccurately tout fermented foods as a good source of probiotics. Typically, only certain yogurts and other cultured dairy products meet the criteria — although the types of foods available with added probiotics are growing. A good way to know if your fermented food contains a true probiotic is if the labels show the genus, species and strain, such as Lactobacillus acidophilus NCFM (with NCFM the designated strain).  

“This information is provided on roughly half of foods in the refrigeration case claiming to be probiotic,” says Sanders. “Consumers may not understand what this means, but it’s a good indication that a legitimate probiotic is included.”

While raw or unpasteurized versions of sauerkraut, kimchi, pickles and other fermented vegetables are increasingly available in the refrigerated aisle in supermarkets and natural food stores, they are likely not probiotic foods. Even if you see the words “naturally fermented” or “naturally probiotic” on package labels, there is no assurance that the product contains probiotics. While those products may contain live microbes compared to canned or jarred, unrefrigerated varieties, that doesn’t mean they contain validated probiotic strains.

Many popular fermented foods and beverages no longer contain live microbes.

While fermented foods are always made with microorganisms, not all fermented foods retain those live microbes when consumed. Many fermented products like sourdough bread, sauerkraut, kimchi, chocolate, coffee, wine and beer are baked, roasted, pasteurized or filtered. This means the live microbes will be killed and any benefit of those microbes is no longer available.

“If the product is stored at room temperature, it’s usually a good bet it does not contain live microbes,” says Hutkins.

It gets a little tricky with cheeses. Some soft cheeses like chevre contain live microbes, but others like cottage cheese are heated to stop the fermentation process, so microbes are killed. Some brands add live microbes after pasturization, so check labels if you prefer a “cultured cottage cheese” with live microbes.

Many hard cheeses, such as cheddar and gouda, contain live microbes, yet long-aged cheeses, like Parmesan, contain less since many of the live microbes die during storage. The live microbes will also be killed if the cheese is cooked. Processed cheeses like American cheese slices are pasteurized for a longer shelf-life and do not contain live microbes.

Few cheeses qualify as probiotics, although some cheeses do add probiotics, which would be indicated on the label.

Fermentation and pickling are not the same thing. Most pickles and olives on supermarket shelves have not been fermented and do not contain live microbes. These days a “quick pickling” method with vinegar is frequently used, which does not result in fermentation or the growth of live microbes. However, some pickles and olives are fermented using a salt brine. This process creates a desirable change in the food’s structure and flavor, encouraging the growth of good bacteria. Harmful microbes are controlled by the acid and salt.

It can be confusing that both fermented and unfermented products like pickles and olives are available, says Hutkins. Plus, some fermented vegetables are often heat processed to make them shelf-stable, which kills the live microbes. Look for fermented pickles and olives in the refrigerated section of the store. Typically the label will identify if the product is fermented.

Except for yogurt and cultured dairy products, few human clinical studies have been conducted to verify the health benefits of fermented foods, although this is changing. Thanks in part to the considerable consumer interest in fermented foods, says Hutkins.

Scientific evidence for the positive health effects of fermented foods has relied more on epidemiological or population-based studies, primarily in Asian countries that regularly consume fermented foods and beverages, especially fermented soy products (natto and miso) and fermented cabbage (kimchi).

The most significant study to date on fermented foods was conducted in 2021 by Stanford researchers and published in the journal Cell. In this 10-week intervention, a diet rich in fermented foods, including yogurt, fermented cottage cheese, kefir and kombucha, increased gut microbiome diversity and decreased markers of inflammation.

A more recent study that analyzed national food consumption data found that a higher intake of microbe-containing food was associated with multiple positive health outcomes, including lower blood pressure, BMI, waist circumference, blood sugar and triglycerides, along with higher HDL – the “good cholesterol.”

So even if fermented foods do not meet the probiotic definition, most still contain high numbers of live microorganisms, as well as byproducts of the fermentation process that include various vitamins and lactic and citric acids. Fermentation may also produce prebiotic fibers, which help fuel the good bacteria in the gut.

The growing evidence supporting the benefits of fermented foods has led scientists to push for including fermented foods in the Dietary Guidelines for Americans, establishing a daily recommendation to eat more microbes.