Microbiome Myth Busting: Is there really a difference between fermented foods and probiotics?

Consuming a healthy diet is one of the simplest ways we can improve our gut health. After all, what feeds us also feeds our gut bugs!

Fermented foods have been part of the human diet for over 10,000[1] years and have only increased in popularity thanks to the discovery of their various health promoting qualities.

However, not all fermented foods are created equal, and therefore it is important to understand the difference between fermented food types, the benefits they offer and how this differs from probiotic supplements. So, let’s explore the science behind fermented foods and probiotics, so that you can make the right choice for you!

What are fermented foods?

Fermented foods are defined as foods that have undergone enzymatic reactions in response to microbes, and are made up of various health promoting properties, including nutrients, prebiotics, probiotics and microbial metabolites. Fermented foods can be made from multiple food sources, such as dairy, grains, vegetables, fruits, meats, fish and legumes, with some common examples including kefir, kombucha, wine, sauerkraut, miso, yogurt and sourdough bread.[2][3]

While fermentation was originally used as a process to preserve foods, it was later discovered that regularly consuming fermented foods offered a variety of health benefits, including longevity.¹ When investigating the mechanisms behind these health benefits, researchers discovered the following:

• Fermentation increases the nutrient availability of foods and therefore can improve the digestibility of certain food types
• Fermented foods contain food components, such as prebiotics, which provide a food source for pre-existing microbes within the gut
• Microbes found in fermented foods are often able to survive the harsh journey of the digestive tract, and are therefore able to interact with the gut microbiome

In addition to these actions, fermented foods are considered relatively safe and inexpensive, making them a valuable dietary tool to help support general health and wellbeing.[3][4]

Probiotics Vs fermented foods: What’s the difference?

While often talked about interchangeably, fermented foods and probiotics are not one and the same.

Probiotics are defined as live microorganisms that when administered in adequate amounts, confer a health benefit to the host.[5] The health benefits of probiotics are specific to the type of probiotic strain and the amount of colony forming units (CFU) of that strain. Different health imbalances benefit from different probiotic strains and doses, and this is determined by the results of human clinical trials.[6]^,[7]

While fermented foods also contain beneficial microbes, the types and numbers of beneficial microbes can vary significantly between fermented food types (e.g., dairy, grains or vegetables), and the cooking or processing techniques that are applied to the food after fermentation.

Differences between fermented food types:

For instance, while yoghurt and sourdough bread are both classified as fermented foods, both provide very different health outcomes when consumed regularly. The same can be said of fermented beverages, such as kombucha and alcohol.
Furthermore, people with pre-existing health imbalances, such as medically diagnosed irritable bowel syndrome (MD-IBS), find different fermented foods can either relieve or contribute to their symptoms, depending on the type. For example, fermented dairy can help improve dairy tolerance, whereas fermented cabbage can reduce tolerance.
This change in tolerance is due to an increase in the presence of fermentable di-, oligo- and mono-saccharides and polyols (FODMAPs) found in certain cabbages after the fermentation process.[8][9]

Differences between fermented food processing:

For instance, sourdough bread is a fermented food that contains live microbes in its raw form, however, once the bread is cooked, these microbes are no longer alive.

Are fermented foods right for me?

If there is one thing we have learnt in recent years when it comes to the question of ‘what makes up a healthy diet’, it is that there is no one-size-fits all approach and your dietary needs are unique to you. When it comes to fermented foods, different fermented food types can offer different health benefits to different people, and finding the right fermented food type for you may help support your daily, general health needs.

In summary:

Fermented foods are foods that are rich in microbes and have undergone enzymatic processes. Fermented foods such as yoghurt, kefir and sauerkraut, are generally considered highly nutritious food sources and can offer a variety of health benefits. Better yet, they are a convenient and affordable dietary tool which can be used to support your general health needs.

Probiotic supplements, by definition, must contain live, beneficial microbes delivered in an adequate amount to provide health benefits. Probiotic benefits are specific to the type and the amount of probiotic contained in the supplement, and this is determined by human clinical trials. When it comes to specific health needs, probiotic supplements can provide a targeted therapeutic approach by providing consistency of strain types and dosing, in line with clinical evidence.

If you are not sure if fermented foods, probiotics, or both, are suited to your health needs, we recommend consulting your healthcare professional for more tailored advice.

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[1] Leeuwendaal NK, Stanton C, O’Toole PW, Beresford TP. Fermented foods, health and the gut microbiome. Nutrients. 2022 Apr 6;14(7):1527.

[2] Dimidi E, Cox SR, Rossi M, Whelan K. Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease. Nutrients. 2019 Aug 5;11(8):1806

[3] Marco ML, Heeney D, Binda S, Cifelli CJ, Cotter PD, Foligné B, et al. Health benefits of fermented foods: microbiota and beyond. Curr Opin Biotechnol. 2017 Apr 1;44:94–102.

[4] Castellone V, Bancalari E, Rubert J, Gatti M, Neviani E, Bottari B. Eating Fermented: Health Benefits of LAB-Fermented Foods. Foods. 2021 Oct 31;10(11):2639.

[5] Hill C, Guarner F, Reid G, Gibson GR, Merenstein DJ, Pot B, Morelli L, Canani RB, Flint HJ, Salminen S, Calder PC. 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.

[6] World Gastroenterology Organisation [Internet]. Probiotics and prebiotics. 2017. Available from: https://www.worldgastroenterology.org/guidelines/probiotics-and-prebiotics/probiotics-and-prebiotics-english

[7] Probiotics [Internet]. International Scientific Association for Probiotics and Prebiotics (ISAPP). [cited 2023 Feb 27]. Available from: https://isappscience.org/for-scientists/resources/probiotics/

[8] Biesiekierski JR, Tuck CJ. Low FODMAP diet beyond IBS: Evidence for use in other conditions. Curr Opin Pharmacol. 2022 Jun 1;64:102208.

[9] Parker EA, Roy T, D’Adamo CR, Wieland LS. Probiotics and Gastrointestinal Conditions: An Overview of Evidence from the Cochrane Collaboration. Nutr Burbank Los Angel Cty Calif. 2018 Jan;45:125-134.e11.