Fermented Foods vs. Probiotics: What’s the Difference?

In this article

1. What Are Fermented Foods?
2. What Are Probiotics?
3. Fermented Foods vs. Probiotics: What’s the Difference?
4. Why Aren’t All Fermented Foods Probiotic?
5. Do Live Microorganisms Survive Fermentation?
6. What Happens to Live Cultures During Pasteurization and Cooking?
7. Fermented Pickles vs. Vinegar Pickles
8. Which Fermented Foods Can Contain Live Cultures?
9. How to Read a Fermented Food Label
10. Do Fermented Foods Still Have Benefits Without Live Microorganisms?
11. Frequently Asked Questions
12. Final thoughts

Fermented foods and probiotics are often discussed together, especially when it comes to gut health and digestion. But they are not the same thing, and a fermented food is not automatically a probiotic food.

Fermentation describes a process in which microorganisms transform components of a food or beverage. Some fermented foods still contain live microorganisms when we eat them, while others lose these microorganisms during pasteurization, cooking, or other processing.

Probiotics have a more specific meaning. They are live microorganisms that provide a health benefit when consumed in adequate amounts. This means that the presence of live cultures alone does not automatically make a fermented food probiotic.

What Are Fermented Foods?

Fermented foods are foods or beverages produced through desired microbial growth and enzymatic conversion of food components. This definition comes from the International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods.

During fermentation, microorganisms such as bacteria, yeasts, and certain molds transform components naturally present in food. Depending on the food and fermentation process, they can produce substances such as lactic acid, alcohol, carbon dioxide, and numerous other compounds.

These transformations can change the flavor, aroma, texture, and shelf life of a food. Milk can be transformed into yogurt or kefir, cabbage into sauerkraut or kimchi, and soybeans into foods such as miso, tempeh, and natto.

However, fermented foods are a very diverse group. The microorganisms involved in yogurt fermentation are not necessarily the same as those found in fermented vegetables, sourdough, kombucha, or fermented soy foods.

Fermentation therefore tells us something about how a food was produced. It does not tell us automatically whether that food contains live microorganisms when we eat it.

What Are Probiotics?

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. This widely used definition was established by an expert consensus of ISAPP.

The words live and health benefit are both important. Simply finding bacteria or other microorganisms in a food does not automatically mean that they are probiotics.

A microorganism also needs to be sufficiently characterized and associated with a particular health benefit under appropriate conditions. Different microorganisms and strains may have different effects.

This is one of the most important distinctions when comparing probiotics with fermented foods: live cultures are not automatically probiotic cultures.

Fermented Foods vs. Probiotics: What’s the Difference?

The easiest way to understand the difference is to look at what each term describes. Fermented food describes a food and the process used to make it, while probiotic describes live microorganisms associated with a health benefit.

The two categories can overlap, but they should not be used as synonyms.

	Fermented Foods	Probiotics
What are they?	Foods or beverages produced through fermentation	Live microorganisms
What does the term describe?	How the food was produced or transformed	Microorganisms and their associated health benefit
Must microorganisms still be alive when consumed?	No	Yes
Are live microorganisms enough?	They are not required in the final food	No; an adequate amount and health benefit are also required
Where can we find them?	Yogurt, kefir, fermented vegetables, kimchi, miso and many other foods	Certain foods and probiotic products containing appropriately characterized microorganisms

A fermented food can contain live microorganisms without necessarily being probiotic. Conversely, probiotic microorganisms can be incorporated into products where their identity, amount, and intended benefit are more specifically defined.

Why Aren’t All Fermented Foods Probiotic?

There are two main reasons.

First, the microorganisms responsible for fermentation do not necessarily survive until the food reaches our plate. They may perform their role during fermentation and then be inactivated by heating or other processing.

Sourdough bread is a good example. Bacteria and yeasts participate in fermentation of the dough, making sourdough a fermented food, but the high temperatures used during baking inactivate most of these microorganisms.

Second, even when a fermented food still contains live microorganisms, their presence alone does not establish a probiotic benefit. Live microorganisms found naturally in fermented foods may not have been characterized or studied in the same way as microorganisms used specifically as probiotics.

For this reason, the terms fermented, live cultures, and probiotic should not be treated as interchangeable.

Do Live Microorganisms Survive Fermentation?

They can. Many fermented foods contain living microorganisms at the end of fermentation, but whether those microorganisms are still alive when the food is eaten depends on what happens afterward.

Foods that are consumed without additional heat treatment may retain substantial populations of live microorganisms. Yogurt, kefir, some fermented vegetables, and certain other refrigerated fermented foods are common examples.

Processing and storage can change this. Pasteurization, baking, boiling, and other heat treatments can substantially reduce or inactivate microorganisms that were present after fermentation.

Time and storage conditions matter as well. Temperature, acidity, oxygen exposure, and the characteristics of the food itself can influence how microbial populations change during storage.

This is why two versions of the same type of fermented food may not necessarily contain the same live cultures when they reach the consumer.

What Happens to Live Cultures During Pasteurization and Cooking?

Heat can inactivate many of the microorganisms present in fermented foods. If a product is pasteurized after fermentation, the number of viable microorganisms can be greatly reduced or the microorganisms may no longer be alive.

Cooking can have a similar effect. Sourdough bread is baked, tempeh is commonly cooked before eating, and miso may be added to hot dishes.

However, killing the microorganisms does not reverse fermentation. The food has already undergone microbial and enzymatic transformations before being heated.

This distinction is important because a fermented food without live cultures is still a fermented food. It simply should not be assumed to provide living microorganisms at the time it is consumed.

Fermented Pickles vs. Vinegar Pickles

Pickles are a particularly useful example because a sour taste does not necessarily mean that a food has been fermented. Vegetables can become acidic through microbial fermentation or through the direct addition of vinegar.

Traditional fermented vegetables are commonly prepared in brine. During fermentation, lactic acid bacteria use sugars naturally present in the vegetables and produce lactic acid, which contributes to the characteristic sour taste and acidic environment.

Vinegar pickles are different. Vinegar provides acidity directly, so a product preserved primarily by adding vinegar should not automatically be considered a fermented food.

Product	How It Is Made	Can It Contain Live Microorganisms?
Sauerkraut fermented in brine	Lactic acid fermentation	Yes, if it remains unpasteurized
Brine-fermented cucumbers	Lactic acid fermentation	Yes, if they remain unpasteurized
Vinegar pickles	Acidified directly with vinegar	Live fermentation cultures should not be assumed
Fermented and pasteurized pickles	Fermentation followed by pasteurization	Live microorganisms may be inactivated

The practical distinction is therefore not simply pickled vs. not pickled. If you are specifically looking for fermented vegetables with live cultures, the fermentation method and subsequent processing matter.

Which Fermented Foods Can Contain Live Cultures?

Some fermented foods can retain live cultures and live microorganisms until they are eaten, particularly when they have not been pasteurized or heated after fermentation.

The table below focuses specifically on fermented foods that can contain live microorganisms at the time of consumption. Their actual microbial content depends on how each product is produced, processed, stored, and prepared.

Fermented Food	Common Microorganisms or Cultures	What to Check
Yogurt	Lactic acid bacteria	Look for live cultures and check for heat treatment after fermentation
Kefir	Lactic acid bacteria and yeasts	Live cultures and storage instructions
Some cheeses	Various bacteria involved in fermentation and ripening	Type of cheese and processing method
Sauerkraut	Lactic acid bacteria	Choose fermented, unpasteurized products when looking for live cultures
Brine-fermented cucumbers	Lactic acid bacteria	Check that they are fermented rather than simply preserved in vinegar
Fermented olives	Lactic acid bacteria and yeasts	Processing and pasteurization
Kimchi	Lactic acid bacteria	Check for pasteurization or subsequent cooking
Kombucha	Bacteria and yeasts	Check whether the product has been pasteurized
Unpasteurized miso	Microorganisms involved in fermentation	Pasteurization and heating during preparation
Natto	Bacillus subtilis var. natto	Processing and subsequent heat treatment
Unpasteurized kvass	Yeasts and lactic acid bacteria	Fermentation method and pasteurization
Lacto-fermented vegetables	Lactic acid bacteria	Fermentation in brine and subsequent pasteurization

This is not a list of probiotic foods. It is a list of fermented foods that may deliver living microorganisms when consumed.

Even when live microorganisms are present, that alone does not establish a specific probiotic benefit. This distinction is particularly important when food labels or marketing use terms such as fermented, live cultures, and probiotic close together.

How to Read a Fermented Food Label

The word “fermented” alone does not tell us whether a product still contains live microorganisms. If live cultures are important to you, several other pieces of information on the label can be useful.

Phrases such as “live cultures” or “live and active cultures” can indicate that living microorganisms are present. They still do not automatically mean that the food provides a demonstrated probiotic benefit.

What to Look For	What It Can Tell You
Live cultures	The manufacturer indicates that living cultures are present
Live and active cultures	Indicates the presence of live, active cultures
Pasteurized after fermentation	Heat treatment occurred after fermentation and may have inactivated live microorganisms
Culture names	May identify microorganisms used in the product
Storage instructions	Explain how the product should be stored
Preparation instructions	Heating or cooking may affect live cultures

Refrigeration by itself does not prove that a food contains live microorganisms. Many foods require refrigeration for reasons unrelated to probiotic or fermentation cultures.

Similarly, unpasteurized does not automatically mean healthier. Food safety remains important, particularly for people who may be more vulnerable to foodborne illness.

Do Fermented Foods Still Have Benefits Without Live Microorganisms?

Fermentation changes a food before we eat it, so the effects of the process are not limited to whether microorganisms remain alive in the final product. Microbial activity can transform carbohydrates, proteins, and other components of the original food.

Depending on the food and fermentation process, fermentation can produce organic acids, peptides, and other compounds. It may also influence digestibility and nutrient availability or reduce certain compounds that can interfere with nutrient absorption.

These effects vary considerably among fermented foods. Yogurt, fermented vegetables, sourdough, miso, and fermented soy products are different foods with different nutrient profiles and fermentation processes, so they should not be expected to produce identical effects.

A 2021 clinical study published in Cell compared diets high in fermented foods with diets high in fiber. In the fermented-food group, researchers observed increased gut microbiota diversity and changes in several markers of immune activity and inflammation. The study was relatively small, however, and its findings should not be interpreted as proof that every fermented food produces the same effects.

This distinction is useful when evaluating fermented foods: a food does not need to qualify as probiotic to remain nutritionally interesting. The effects of fermentation itself and the effects of live probiotic microorganisms are related topics, but they are not the same question.

Written by Victoria, founder and editor of RoutineHealth. This article is for general education and is not medical advice. It should not be considered medical or nutritional advice. Individual dietary needs and health risks vary, and questions about specific foods, supplements, or health conditions should be discussed with an appropriate healthcare professional. Unpasteurized foods can carry a higher risk of foodborne illness for some people, including pregnant women, young children, older adults, and people with weakened immune systems. Food safety recommendations should therefore be considered separately from whether a fermented product contains live cultures. How we research and correct articles is explained in our Editorial Policy; see also our Medical Disclaimer.

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