Fermented foods: Which foods contain live cultures?

Sauerkraut, yogurt, kimchi, kefir, or sourdough – fermented foods are more common than you might initially think. Microorganisms like bacteria or yeast play a crucial role in their production. However, an important distinction is often overlooked: Not every fermented food still contains live cultures when consumed. And "fermented" does not automatically mean probiotic or postbiotic.

This overview shows which foods can actually contain live microorganisms, how to identify them, and what distinguishes fermented, probiotic, prebiotic, and postbiotic foods from one another.

What are fermented foods?

During fermentation, foods are altered with the help of microorganisms and their metabolic processes. Bacteria, yeast, or other microorganisms convert components of the original food.

For instance, sugar can be turned into lactic acid or other metabolic products. This changes the flavor, consistency, and shelf life of the food. Humans have been using exactly these processes for centuries to produce a wide variety of foods.

Typical examples include:

• Yogurt and kefir
• Sauerkraut
• Kimchi
• Sourdough
• Kombucha
• Miso
• Tempeh
• Certain types of cheese

However, it is important to note: The microorganisms required for fermentation do not necessarily have to be alive in the final food product. Some products are heated, pasteurized, baked, or filtered after fermentation. This can reduce or completely inactivate the microorganisms present during fermentation.

Fermented foods: List with examples

Whether a fermented food contains live cultures when consumed depends heavily on its production and processing.

Food	Fermented?	Live cultures possible upon consumption?
Natural yogurt	Yes	Often yes
Kefir	Yes	Often yes
Sauerkraut	Yes	Yes, if it was not subsequently heated
Kimchi	Yes	Often yes
Kombucha	Yes	Depending on product and processing
Sourdough bread	Yes	Generally no
Miso	Yes	Depending on processing
Tempeh	Yes	Yes before heating, significantly reduced after cooking
Cheese	Depending on variety	Depending on production
Pickles	Not automatically	Only with actually fermented varieties

This overview already shows: The term "fermented" tells us something about the production process – not whether live microorganisms are still present in the finished product.

Which fermented foods contain live cultures?

Live microorganisms are found most frequently in fermented foods that are not subjected to high heat or pasteurization after production.

These can include, for example, refrigerated, unpasteurized sauerkraut, kimchi, some yogurts, kefir, or certain kombucha products.

However, even here, it is not possible to make a blanket statement about what quantity or specific microorganisms a food contains at the time of consumption. Production, storage, temperature, and shelf life can influence the composition and number of microorganisms.

Therefore, for packaged products, it is worth taking a close look at the packaging and the manufacturer's information.

Fermented does not automatically mean probiotic

In everyday language, "fermented" and "probiotic" are often used interchangeably. Scientifically, however, these are different terms.

A fermented food is produced through the targeted growth of microorganisms and the resulting transformation of its components.

For microorganisms to be scientifically classified as probiotics, specific requirements must be met. Among other things, they must be defined live microorganisms for which a health benefit has been proven at a specific dosage.

In contrast, the microorganisms in traditionally fermented sauerkraut or kimchi are often neither present in a standardized quantity nor defined down to specific strains.

Therefore, the rule is:

A food can contain live microorganisms without automatically being considered a probiotic food.

The term "probiotic" should therefore not be applied generally to all fermented foods or products containing live cultures.

Probiotic foods: what does that mean?

The term "probiotic" does not simply refer to any food produced by microorganisms or containing live cultures. Instead, it refers to defined live microorganisms for which a health benefit has been proven under certain conditions.

Some products are specifically manufactured with certain cultures and labeled accordingly. With traditionally fermented foods, on the other hand, it is often not clearly known which microorganisms are present and in what quantities at the time of consumption.

Yogurt

In yogurt production, lactic acid bacteria convert milk sugar into lactic acid. This gives it its typical consistency and slightly acidic taste.

Many yogurts still contain live yogurt cultures upon consumption. However, it does not automatically follow that every yogurt product can be classified as probiotic.

Kefir

Kefir is also produced through fermentation, during which various bacteria and yeasts work together. Traditionally produced kefir can contain a multitude of live microorganisms at the time of consumption.

Which microorganisms are actually present depends, among other things, on the cultures used, the production process, and storage.

Kimchi

Kimchi is a traditional Korean fermented vegetable dish, often made from napa cabbage, radish, spices, and salt. During fermentation, lactic acid bacteria, in particular, multiply.

If the kimchi is not subsequently pasteurized, live microorganisms may remain in the ready-to-eat product. However, this characteristic alone does not automatically make kimchi a probiotic food.

Sauerkraut

In traditional sauerkraut, finely shredded cabbage is fermented with the help of lactic acid bacteria.

Fresh or refrigerated, unpasteurized sauerkraut can contain live microorganisms. Conversely, sauerkraut from cans or jars is often heated to give it a longer shelf life, which can reduce the number of live cultures.

Kombucha

Kombucha is produced by the fermentation of sweetened tea using a community of bacteria and yeasts.

Unpasteurized kombucha can therefore contain live microorganisms. Here, too, the actual composition depends heavily on the production method, the product, and storage.

What are postbiotic foods?

In addition to fermented, probiotic, and prebiotic foods, the term postbiotic is increasingly being used.

Simply put, postbiotics are inactivated microorganisms and components or metabolic products of microorganisms that may provide health benefits. Unlike probiotics, they do not need to be alive.

These can include, for example:

• Components of bacterial cells
• inactivated microorganisms
• enzymes
• organic acids
• certain metabolic products
• other substances formed during fermentation

However, the term is not synonymous with "fermented." A fermented food may contain postbiotic components but is not automatically considered a postbiotic product. For this, the contained components must be characterized in more detail and a health benefit must be proven under certain conditions.

Even a heated fermented food may still contain metabolic products or components of the originally involved microorganisms. Although the microorganisms may no longer be alive due to heating, the substances generated during fermentation may be partially preserved.

Which fermented foods no longer contain live cultures?

Even foods without live microorganisms can clearly be fermented foods.

This may sound contradictory at first, but it is simple to explain: what is decisive for the designation "fermented" is the production process.

If the microorganisms are subsequently inactivated by heat or other processing steps, the food nevertheless remains a result of fermentation.

A good example of this is sourdough bread.

Is sourdough probiotic or postbiotic?

For sourdough, lactic acid bacteria and yeasts work together. Among other things, they ensure that the dough rises and develops its typical aroma.

However, temperatures reached during baking mean that most of these microorganisms do not survive.

Sourdough bread is therefore a fermented food, but generally no longer contains living cultures after baking.

During fermentation, however, various metabolic products are created that contribute to the flavor, odor, and properties of the bread. Whether a finished sourdough bread can therefore be described as a postbiotic food cannot be said in general terms. For that, the contained components and any potential health benefits would need to be more precisely researched and defined.

The same applies to other fermented products that are heavily heated, roasted, pasteurized, or filtered after fermentation.

What are prebiotic foods?

In addition to fermented, probiotic, and postbiotic foods, another term frequently appears: prebiotic foods.

Prebiotic and probiotic do not mean the same thing.

Prebiotics are specific substances that are utilized by microorganisms and can thereby provide a health benefit. These are often certain non-digestible or only partially digestible carbohydrates.

Foods that contain corresponding dietary fibers include, for example:

• Chicory
• Jerusalem artichoke
• Onions
• Garlic
• Leeks
• Certain whole grain products
• Legumes

A food does not have to be fermented for this, nor does it necessarily contain living microorganisms.

Fermented, probiotic, prebiotic, or postbiotic: What is the difference?

In simplified terms, the terms can be distinguished as follows:

• Fermented:
  The food was produced or modified with the help of microorganisms and their metabolic processes.
• With living cultures:
  The food still contains living microorganisms at the time of consumption.
• Probiotic:
  Specific living microorganisms meet defined scientific requirements, and a health benefit has been proven for them in sufficient quantities.
• Prebiotic:
  Specific components of a food are utilized by microorganisms and can thereby provide a health benefit.
• Postbiotic:
  Inactivated microorganisms or components or metabolic products of microorganisms can provide a health benefit under certain conditions. The contained microorganisms do not have to be alive.

This distinction is particularly helpful for consumers: sourdough bread, for example, is fermented but usually does not contain living cultures after baking. Unpasteurized kimchi, on the other hand, can be fermented and at the same time contain living microorganisms. However, these are not automatically classified as probiotics for this reason. A heated fermented food can, in turn, contain certain metabolic products or components of the microorganisms without still exhibiting living cultures.

Are fermented foods healthy?

Fermented foods are increasingly being researched scientifically. Among other things, researchers are interested in how the fermentation process affects the composition of a food and the microorganisms and metabolic products contained within it.

Fermentation can, for example, change the shelf life, taste, and availability of certain nutrients. At the same time, fermented foods can contain living microorganisms, inactivated cell components, as well as various metabolic products of fermentation.

What significance these components have for health depends on the specific food, the substances contained, the quantity consumed, and other individual factors.

Nevertheless, the blanket statement "fermented foods are healthy" would be too simplistic.

The decisive factor is always the specific food and its composition.

After all, natural yogurt, kimchi, sauerkraut, kombucha, or sourdough bread differ considerably in terms of ingredients, nutritional values, and processing.

Can fermented foods also be unhealthy?

Fermentation does not automatically make a food healthy—but neither does it automatically make it unhealthy.

When choosing, it is therefore worth looking at the entire product.

• Salt:
  Products such as sauerkraut, kimchi, miso, or certain types of cheese can contain relatively large amounts of salt.
• Sugar:
  For kombucha and other fermented beverages, it is worth checking the sugar content of the finished product.
• Processing:
  Pasteurization or intense heating can mean that microorganisms originally present are no longer alive. At the same time, certain metabolic products or cell components can be partially preserved.
• Individual tolerance:
  Not every food is equally well tolerated by every person. Anyone who is not used to certain foods can, for example, start with smaller quantities.

A single fermented food should therefore not be evaluated in isolation. What is crucial is how it fits into your overall diet.

How can you tell if a fermented food contains live cultures?

For supermarket products, it is not always apparent at first glance whether live microorganisms are still present.

A few clues can help when making a selection:

• Pay attention to processing:
  Labels such as "pasteurized" or "heat-treated" indicate that many of the originally present microorganisms have been inactivated by processing.
• Check for refrigeration:
  Products with live cultures are often sold in the refrigerated section. However, a requirement for refrigeration alone is not definitive proof.
• Read the ingredients and product information:
  Some manufacturers list the cultures or microorganisms used on the packaging.
• Do not rely solely on the term "fermented":
  This describes the production method, not the amount of live microorganisms or postbiotic components in the finished product.
• View postbiotic claims critically:
  The term "postbiotic" should not be applied as a blanket statement to every heated or fermented food. Specific details about the contained components and the scientific basis are more meaningful.

How can you integrate fermented foods into your daily routine?

Fermented foods do not have to be unusual specialty products. Many of them can easily be incorporated into regular meals.

For breakfast, options could include plain yogurt or kefir. Unpasteurized sauerkraut or kimchi can be used as a small side dish. Sourdough bread is a suitable alternative to other types of bread, even if it no longer contains live cultures after baking.

Those who rarely eat fermented foods do not need to change their entire diet all at once. Trying different foods and paying attention to individual tolerance is usually the easier path.

Frequently asked questions about fermented foods

Which foods are fermented?

Some of the most well-known fermented foods include yogurt, kefir, sauerkraut, kimchi, sourdough bread, kombucha, miso, tempeh, and certain types of cheese. Whether they still contain live microorganisms upon consumption depends on how they are further processed.

Which fermented foods contain live cultures?

Unpasteurized products such as certain yogurts, kefir, fresh sauerkraut, kimchi, or kombucha can contain live microorganisms. However, the actual quantity and composition depend on the specific product.

Is every fermented food probiotic?

No. A fermented food does not automatically meet the scientific definition of a probiotic. Among other things, this requires the presence of defined microorganisms in a specific quantity and scientifically proven health benefits.

What are postbiotic foods?

Postbiotic foods contain inactivated microorganisms or components, or metabolic products of microorganisms, which may provide health benefits under certain conditions. The microorganisms included do not have to be alive.

Is sourdough probiotic?

Sourdough is fermented with the help of live microorganisms. However, these are largely inactivated during baking by high temperatures. Sourdough bread is therefore fermented, but usually does not contain live cultures when eaten.

Whether specific metabolic products created during fermentation are retained depends on production and processing. However, it cannot be automatically inferred that every sourdough bread is postbiotic.

Does sauerkraut contain live cultures?

That depends on the processing. Raw or unpasteurized sauerkraut can contain live microorganisms. If, however, sauerkraut is heated or pasteurized after fermentation, these are significantly reduced or inactivated.

Is kombucha probiotic?

Kombucha can contain live bacteria and yeasts. However, this does not automatically mean that these microorganisms meet the scientific criteria for probiotics.

Can a heated fermented food contain postbiotic components?

In principle, this is possible. Various metabolic products and cell components are formed during fermentation, some of which may be preserved through subsequent heating. However, whether a specific product can be described as postbiotic depends on the exact composition and scientific assessment.

What is the difference between probiotic, prebiotic, and postbiotic foods?

Probiotics are defined live microorganisms that, when consumed in sufficient amounts, confer a proven health benefit. Prebiotics are substances that are utilized by microorganisms and can thereby confer a health benefit. Postbiotics are inactivated microorganisms or components, or metabolic products of microorganisms, that may provide health benefits under certain conditions.

Can you eat fermented foods every day?

Fermented foods can be part of a varied diet. However, the appropriate amount depends on the specific food, its composition, and individual tolerance. There is no general recommended daily amount for fermented foods.

Conclusion: Fermented does not equal probiotic or postbiotic

Yogurt, sauerkraut, kimchi, kefir, kombucha, or sourdough all have one thing in common: microorganisms play a decisive role in their production.

However, whether these microorganisms are still alive upon consumption is a different question. Likewise, one cannot automatically deduce whether a product has probiotic or postbiotic properties simply because it is fermented.

Fermented does not automatically mean "contains live cultures," "probiotic," or "postbiotic."

Those looking specifically for foods with live cultures should therefore pay closer attention to production and processing. Unpasteurized or non-heat-treated products may contain live microorganisms, whereas these are largely inactivated, for example, when baking sourdough bread.

Postbiotic components can also play a role even if microorganisms are no longer alive. However, the term should only be used when the relevant components and a potential health benefit have been sufficiently characterized and scientifically evaluated.

It is precisely these differences that make fermented foods so diverse – from centuries-old production methods to modern products that focus on living microorganisms, prebiotic substances, or postbiotic components.