What are probiotics?

Probiotics are most precisely defined as live microorganisms which, when administered in adequate amounts, confer a health benefit on the host. This definition, established by the Food and Agriculture Organisation (FAO) and World Health Organisation (WHO), remains the international consensus and is widely adopted in clinical and regulatory contexts.^[1-3] The term should not be used to describe all bacteria, fermented foods, or microbial products; only those strains that meet specific criteria qualify.

To be classified as a probiotic, a microorganism must satisfy four key criteria: 

(1) be sufficiently characterised at the strain level

(2) be demonstrated as safe for the intended use

 (3) be supported by at least one positive human clinical trial conducted according to accepted scientific standards, and 

(4) remain alive in the product at an efficacious dose throughout its shelf life.^[1][4] 

Common genera include Lactobacillus, Bifidobacterium, Saccharomyces, and select strains of Bacillus, Enterococcus, and Streptococcus.^[5-6]

Importantly, health benefits are strain-specific and not all strains within a species confer the same effects. The clinical efficacy and safety must be established for each strain and indication, and the term "probiotic" should not be applied to products or strains lacking such evidence.^[1][4][7] This precision is essential for scientific communication, regulatory oversight, and clinical practice.

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What is the difference between Probiotic and Fermented Food?

The key distinction is that - as above - probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, and must be characterised to the strain level with demonstrated clinical efficacy. 

In contrast, fermented foods are foods or beverages produced through controlled microbial growth and enzymatic conversion of food components, but they do not necessarily contain live microorganisms with proven health benefits, nor do they require strain-level characterisation or clinical validation to be considered fermented foods.^[8-10]

Most fermented foods (e.g., yogurt, kimchi, sauerkraut, kefir) contain live microbes, but these are not automatically considered probiotics unless the specific strains present have been clinically shown to confer health benefits in humans. Many fermented foods may contain dead microbes or strains with no proven health effects, and the microbial content can vary widely between batches and products.^[8-9][11] Therefore, while some fermented foods can serve as vehicles for probiotics, the terms are not interchangeable.^[8-9][12]

The American College of Gastroenterology highlights that the mechanisms by which fermented foods may benefit health are distinct and may include effects from bioactive metabolites, changes in food matrix, or modulation of the gut microbiota, but these effects are not necessarily attributable to probiotics unless the above criteria are met.^[10]

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What Exactly is in Your Gut? The Microbiome Explained

While the term "probiotic" can be precise, it refers to a diverse cast of characters that live in an incredibly complex ecosystem right inside you: your gut microbiome.

Think of your gut as a bustling city, home to trillions of microorganisms - bacteria, viruses, and fungi. This community of microbes is essential to your overall health, performing critical tasks that your body can't do alone.

• The Ecosystem: This complex community is often referred to as your microbiome. Maintaining a diverse and balanced city - where the beneficial microbes outnumber the less helpful ones - is key to digestive health.

• The Job Description: These tiny residents are crucial for:

  • Digestion: Breaking down certain complex carbohydrates (like fibre) that your body can't digest.

  • Immunity: Helping to train and support a large part of your immune system, which resides in the gut.

  • Gut-Brain Connection: Communicating with the brain through the gut-brain axis, potentially influencing mood and overall brain health.

Probiotics are the beneficial "good citizens" that you intentionally add to this community to help keep the peace and support a healthy balance.

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Yoghurt and the Power of Live Cultures

So, where does your morning bowl of yoghurt fit in?

While not all fermented foods qualify as probiotics, many yoghurts are an excellent vehicle for delivering these beneficial strains. Here’s what matters:

• Fermentation Starters: All yoghurts are made by adding starter cultures to milk (typically Lactobacillus bulgaricus and Streptococcus thermophilus). These cultures ferment the milk, creating the tangy flavour and thick texture we love.

• The Crucial Addition: For a product to be considered a strong probiotic source, a yoghurt brand must add additional, specific probiotic strains (like certain strains of Bifidobacterium or Lactobacillus) that have been clinically proven to confer a health benefit.

• The "Live and Active" Promise: The most important point is that these beneficial microbes must remain live and present in an adequate amount right up until you eat them.

At Philotrophie, our products are carefully crafted to ensure the survival and effectiveness of these specific, clinically validated strains throughout the shelf life, giving you the best chance to reap the rewards for your gut.

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The Bottom Line: What This Means for You

So, why go through the effort of including these specific, proven strains in your diet? It all comes down to maintaining balance and supporting your overall health.

When administered in those adequate amounts, consuming clinically validated probiotics - like those found in our yoghurt - may help:

• Maintain Digestive Harmony: Probiotics help replenish the beneficial bacteria, which is particularly helpful in maintaining regularity and a balanced gut environment.

• Support Immune Function: Since a significant part of your body's defence system is linked to your gut, maintaining a healthy microbial balance can contribute to overall immune support.

• Aid Nutrient Breakdown: The good bacteria assist in the complex process of breaking down food and potentially improving the absorption of key nutrients.

Including a high-quality probiotic source, like our carefully developed yoghurt, is a simple, delicious step toward supporting your gut's microbial community, and overall health, every day.

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References

1. Criteria to Qualify Microorganisms as "Probiotic" in Foods and Dietary Supplements. Binda S, Hill C, Johansen E, et al. Frontiers in Microbiology. 2020;11:1662. doi:10.3389/fmicb.2020.01662.

2. Sources, Isolation, Characterisation and Evaluation of Probiotics. Fontana L, Bermudez-Brito M, Plaza-Diaz J, Muñoz-Quezada S, Gil A. The British Journal of Nutrition. 2013;109 Suppl 2:S35-50. doi:10.1017/S0007114512004011.

3. Probiotics History. Gasbarrini G, Bonvicini F, Gramenzi A. Journal of Clinical Gastroenterology. 2016 Nov/Dec;50 Suppl 2, Proceedings from the 8th Probiotics, Prebiotics & New Foods for Microbiota and Human Health meeting held in Rome, Italy on September 13-15, 2015:S116-S119. doi:10.1097/MCG.0000000000000697.

4. Probiotics: Definition, Sources, Selection, and Uses. Sanders ME. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2008;46 Suppl 2:S58-61; discussion S144-51. doi:10.1086/523341.

5. Microorganisms With Claimed Probiotic Properties: An Overview of Recent Literature. Fijan S. International Journal of Environmental Research and Public Health. 2014;11(5):4745-67. doi:10.3390/ijerph110504745.

6. A Comprehensive Review of Probiotics and Human Health-Current Prospective and Applications. Sarita B, Samadhan D, Hassan MZ, Kovaleva EG. Frontiers in Microbiology. 2024;15:1487641. doi:10.3389/fmicb.2024.1487641.

7. Probiotics: Mechanism of Action and Gastrointestinal Health: Gut Guardians: Unlocking the Power of Probiotics. Rana A, Smriti. Journal of the Science of Food and Agriculture. 2025;. doi:10.1002/jsfa.70275.

8. Fermented Foods: A Perspective on Their Role in Delivering Biotics. Vinderola G, Cotter PD, Freitas M, et al. Frontiers in Microbiology. 2023;14:1196239. doi:10.3389/fmicb.2023.1196239.

9. Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease. Dimidi E, Cox SR, Rossi M, Whelan K.

Nutrients. 2019;11(8):E1806. doi:10.3390/nu11081806.

10. Non-Prescription Therapeutics. Weingarden AR, Ko CW. The American Journal of Gastroenterology. 2024;119(1S):S7-S15. doi:10.14309/ajg.0000000000002578.

11. Batch-Dependent Microbiota Variation in Mixed Vegetable Fermentations Shapes the Probiotic Potential of Autochthonous Multifunctional Cultures. Botta C, Spada D, Buzzanca D, et al. Food Research International (Ottawa, Ont.). 2025;220:117039. doi:10.1016/j.foodres.2025.117039.

12. Sources, Isolation, Characterisation and Evaluation of Probiotics. Fontana L, Bermudez-Brito M, Plaza-Diaz J, Muñoz-Quezada S, Gil A. The British Journal of Nutrition. 2013;109 Suppl 2:S35-50. doi:10.1017/S0007114512004011.