Two similar words, two different things. We explain what probiotics, prebiotics, synbiotics, and postbiotics are, how fermented products differ from them, and why you will rarely see the word "probiotic" on food labels in Europe.
Probiotics and prebiotics are often mentioned together, so they are easy to confuse. Some are live microorganisms, while others are substances used by gut microorganisms. In recent years, two more concepts have been added: synbiotics and postbiotics. And then there is kefir, sauerkraut, and kombucha, which many refer to as "probiotic food."
In this article, we rely on consensus documents from the International Scientific Association for Probiotics and Prebiotics (ISAPP), a decision by the European Ombudsman, and information from the Food Safety Authority of Ireland (FSAI). You can find the sources at the end of the article, and they are marked in the text with numbers, for example [1]. If you want to first understand how the gut works, read the article "The Gut: how it works and how to support it with diet."
What are probiotics?
In 2014, an ISAPP expert panel confirmed the definition by the World Health Organization and FAO with a small amendment. Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host [1].
Three important points follow from this definition:
- Microorganisms must be alive. Dead bacteria, their parts, or the substances they produce are not considered probiotics [1].
- An adequate amount is required. For example, the Canadian health authority, whose list is cited by ISAPP, accepts certain species of bifidobacteria and lactobacilli when a serving contains 1 billion colony-forming units (CFU) [1].
- Benefits must be proven. Experts emphasize that many effects depend on the specific strain, so what has been researched with one strain cannot be automatically attributed to another [1].
Why is the strain so important?
A bacterial name consists of three parts: genus, species, and strain. For example, Bifidobacterium is the genus, animalis is the species, and the combination of letters and numbers that follows denotes the specific strain. Two strains of the same species can be very different, so one cannot talk about probiotics as if they were a single product [1].
What are prebiotics?
In 2017, ISAPP also updated the definition of prebiotics. A prebiotic is a substrate that is selectively utilized by host microorganisms and confers a health benefit [2]. Simply put, it is a substance that is "eaten" by certain gut microorganisms, rather than all of them indiscriminately.
The best-studied prebiotics are fructans (inulin and fructooligosaccharides, FOS) and galactooligosaccharides (GOS) [2]. Some human milk oligosaccharides, plant polyphenols, and certain polyunsaturated fatty acids are considered candidates, but evidence is still lacking [2].
Are all fibers prebiotics?
No. ISAPP clearly distinguishes prebiotics from most dietary fibers, such as pectins or cellulose, which are used by a very wide variety of microorganisms [2]. The ISAPP website states that the most studied prebiotics are specific types of fibers, but not all dietary fibers are prebiotics [3].
Experts also note that an appropriate dose must produce the desired effect without side effects, such as excessive gas [2]. Therefore, it is worth increasing the amount of rapidly fermentable fibers gradually. We write more about this in the article "Bloating: common causes and daily habits."
Synbiotics and postbiotics: two newer concepts
A synbiotic, according to the 2020 ISAPP consensus, is a mixture comprising live microorganisms and substrate(s) utilized by host microorganisms that confers a health benefit [4]. Two types are distinguished [4]:
- Complementary synbiotic is a combination of a probiotic and a prebiotic. Each component must separately meet the criteria for a probiotic or prebiotic.
- Synergistic synbiotic is a combination where the substrate is selected specifically for the microorganisms being consumed. The components do not separately have to meet the probiotic or prebiotic criteria.
Important: not every food that contains both bacteria and fiber automatically becomes a synbiotic. According to the definition, the health benefit of the combination must be proven [4].
A postbiotic, according to the 2021 ISAPP consensus, is a preparation of inanimate microorganisms and/or their components that confers a health benefit on the host [5]. In other words, this refers to intentionally inactivated bacteria, rather than live ones.
| Concept | What it is | Are the microorganisms alive? | Source |
|---|---|---|---|
| Probiotics | Live microorganisms that provide health benefits in adequate amounts | Yes | [1] |
| Prebiotics | Substrate selectively utilized by host microorganisms | No microorganisms | [2] |
| Synbiotics | A mixture of live microorganisms and a selectively utilized substrate | Yes | [4] |
| Postbiotics | Inanimate microorganisms and/or their parts | No | [5] |
| Fermented foods | Food made through microbial growth and the transformation of food ingredients | Depends on the product | [6] |
Are fermented foods probiotics?
Not necessarily. In 2021, ISAPP defined fermented foods as foods made through desired microbial growth and enzymatic conversions of food components [6]. This definition refers to the production method, not to what remains in the final product.
Experts emphasize that these concepts are not synonyms. It is suggested that the word "probiotic" should only be used when the health benefits of specific, well-characterized live microorganisms have been proven [6]. If such evidence is lacking, a fermented product can be described as containing "live and active cultures," or if no live microorganisms remain, as "produced by fermentation" [6].
| Fermented foods that often retain live microorganisms | Fermented foods that usually do not contain live microorganisms |
|---|---|
| Yogurt and kefir with live cultures | Bread, as it is baked after fermentation |
| Unpasteurized sauerkraut and other fermented vegetables | Heated or pasteurized fermented products |
| Naturally aged cheeses | Soy sauce, vinegar, some kombuchas |
| Unpasteurized kombucha | Wine, most beer varieties, coffee and chocolate after roasting |
In practice, this means: if you want fermented products with live cultures, choose those that were not heated after fermentation. Pickles marinated in vinegar are not fermented, and pasteurized sauerkraut usually no longer contains live bacteria.
Where can you find prebiotics in food?
ISAPP points out that prebiotics are found in onions, garlic, bananas, chicory roots, and Jerusalem artichokes, but they are usually present in small amounts in typical servings [3]. Fructans, especially inulin, are the most studied [2].
| Product | Main prebiotic compound | Inulin content (% of fresh mass) |
|---|---|---|
| Chicory roots | Inulin | 15–20 % [7] |
| Jerusalem artichokes | Inulin | 15–20 % [7] |
| Garlic | Inulin | 15–20 % [7] |
| Asparagus roots | Inulin | 10–15 % [7] |
| Onions, bananas | Fructans | Small amount in a typical serving [3] |
The authors of the same review, based on previous calculations, indicate that with a typical European diet, about 3–11 g of inulin and oligofructose are consumed per day, while in the USA it is about 1–4 g [7]. We write about where else to find fiber in our guide "Fiber: what is it and where is it abundant?"
Important: these research data concern the concepts of probiotics, prebiotics, and fermented products and the composition of food in general. They are not a description of the effect of the fruttberry product and do not replace a doctor's consultation.
Why will you rarely see the word "probiotic" on labels in Europe?
Many are surprised that there are almost no yogurts or supplements on the shelves marked with the word "probiotic." The reason is the European Union Regulation (EC) No. 1924/2006 on nutrition and health claims made on foods.
- The word "probiotic" is considered a health claim. The FSAI indicates that the term "probiotic" on a food label is considered a health claim, and there are no approved health claims for probiotics [8].
- Implications are also not allowed. Since there are no approved claims, terms that imply a probiotic effect are also not permitted [8].
- The Ombudsman agreed with this approach. On December 20, 2024, the European Ombudsman in case 2273/2023/MIK decided that it was reasonable for the Commission to consider labels such as "contains probiotics" as health claims and did not find maladministration [9].
- Countries apply it differently. The authors of the ISAPP blog write that this word was not seen on food in most EU countries for a long time, but Italy, the Czech Republic, and, in 2020, Spain allowed its use, so the EU approach is not fully harmonized [10].
| Label on a food product | What EU rules say | Source |
|---|---|---|
| "Probiotic", "with probiotics" | Considered a health claim; no approved claims exist | [8, 9] |
| Yogurt live cultures and lactose digestion | Permitted claim when at least 100 million CFU/g of specific starter cultures are present | [8] |
| The word "live" alone | Indicating only this is not allowed | [8] |
| Culture names in ingredients | The manufacturer can list them voluntarily | [8] |
What does this mean for you as a consumer? If the word "probiotic" is not on the packaging, it does not mean that the product does not contain live cultures. It is worth reading the ingredients and looking for the names of specific cultures.
How to include them in your daily diet?
- Eat a variety of plants every day. Vegetables, fruits, legumes, whole grain products, and seeds are sources of fiber.
- Choose fermented products with live cultures. Natural yogurt, kefir, or unpasteurized fermented vegetables.
- Combine. For example, kefir with oats and berries is a delicious breakfast combination.
- Increase gradually. Increase the amount of rapidly fermentable fibers slowly to avoid excessive gas [2].
- Don't forget water. Especially if you eat a lot of fiber.
It is worth choosing probiotic supplements, especially in case of health issues or when taking antibiotics, after consulting a doctor or pharmacist, as different strains have been researched for different purposes [1].
Fiber in the fruttberry mix
fruttberry +fiber is a fiber mix. It does not contain live bacteria, so it is not a probiotic, and we do not call it one. It is convenient to mix into water. We write more about the main fiber in the mix in the article "Psyllium: what is it and how to use it?"
Ingredients
- Psyllium husk is the base of the mix.
- Inulin from agave is a soluble fiber fermented in the gut.
- Freeze-dried strawberries (12%) and blackcurrants (8%) provide flavor and color from real berries, not from flavoring.
- Glucomannan from konjac (amorphophallus) tubers is another soluble fiber.
How much fiber is in the mix?
100 g of the mix contains 77 g of fiber. In an independent study by the KTU Food Institute, as much as 84.4 g of fiber per 100 g was found in a sample of our mix. One teaspoon (5 g) provides about 3.86 g of fiber and only 11 kcal.
The mix contains no added sugar, gluten, lactose, or preservatives, and is suitable for vegans. Start with 1 teaspoon with 200–250 ml of water per day, and if you feel well, increase the amount every 3–4 days. The 250 g pack is most convenient for home, and 30 portions of 5 g are best for work and travel.
All fruttberry dietary fibers in one place.
Frequently asked questions
What is the difference between probiotics and prebiotics?
Probiotics are live microorganisms, while prebiotics are substances that are selectively utilized by gut microorganisms [1, 2].
Can you take probiotics and prebiotics together?
Yes. Many dishes naturally contain both, for example, kefir with oats. If the benefit of the combination has been researched, it can be called a synbiotic [4].
Do all fermented products have probiotics?
No. Bread, pasteurized, or heated products usually no longer contain live microorganisms, and even live cultures do not mean that a product is a probiotic [6].
Are all fibers prebiotics?
No. Only substances that are selectively utilized by host microorganisms and whose health benefit has been proven are considered prebiotics [2, 3].
Does the fruttberry mix contain probiotics?
No. This is a fiber mix; it does not contain live bacteria.
Sources
- Hill C, Guarner F, Reid G et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews Gastroenterology & Hepatology. 2014;11(8):506–514.
- Gibson GR, Hutkins R, Sanders ME et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology. 2017;14(8):491–502.
- International Scientific Association for Probiotics and Prebiotics (ISAPP). Prebiotics. Accessed 2026.
- Swanson KS, Gibson GR, Hutkins R et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics. Nature Reviews Gastroenterology & Hepatology. 2020;17(11):687–701.
- Salminen S, Collado MC, Endo A et al. The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nature Reviews Gastroenterology & Hepatology. 2021;18(9):649–667.
- Marco ML, Sanders ME, Gänzle M et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nature Reviews Gastroenterology & Hepatology. 2021;18(3):196–208.
- Kaur N, Gupta AK. Applications of inulin and oligofructose in health and nutrition. Journal of Biosciences. 2002;27(7):703–714.
- Food Safety Authority of Ireland (FSAI). Probiotic Health Claims. Reviewed 2026.
- European Ombudsman. Decision on how the European Commission deals with the labelling of foodstuff that contain probiotics as „health claims“ (case 2273/2023/MIK). 2024.
- Bañares S, Gueimonde M. „Probiotic“ on food labels in Europe: Spain adopts a pioneering initiative. ISAPP. Reviewed 2026.
The information provided is general in nature and does not replace the consultation of a doctor or nutritionist. Scientific data are presented regarding fiber and nutrition in general and are not a description of the properties of a specific product. If you have chronic illnesses, are taking medication, are pregnant, or are breastfeeding, consult a healthcare professional before taking food supplements. A food supplement does not replace a varied and balanced diet.
