What is the difference between fermented and probiotics?

November 24, 2025 •

3 min read

According to the International Scientific Association for Probiotics and Prebiotics, a substance must contain 'live microorganisms which, when administered in adequate amounts, confer a health benefit on the host' to be called a probiotic. This precise definition is the foundational difference between a probiotic and a fermented food.

Quick Summary

Fermented foods undergo a microbial process but don't always contain live, health-conferring probiotics. Probiotics are specific, scientifically validated live microbes given in concentrated doses for targeted health benefits, often in supplements or fortified foods.

Key Points

Definition Distinction: Fermented foods are products created by microbial growth, whereas probiotics are specific live microorganisms with scientifically proven health benefits.
Microbial Consistency: Probiotic supplements contain a consistent, quantified dose of specific strains, while the microbial content in fermented foods can vary greatly.
Targeted vs. General Benefits: Probiotics are chosen for targeted health issues based on clinical evidence, whereas fermented foods offer broad nutritional and general gut support.
Don't Substitute One for Another: Fermented foods should not be considered a replacement for a targeted probiotic supplement, and vice versa; both can play a complementary role.
Check Labels for Viability: When purchasing fermented foods, look for "live and active cultures" to ensure they contain living microbes, as pasteurization can kill beneficial organisms.
Consider a Combined Approach: For comprehensive gut health, consider both consuming a variety of fermented foods for diversity and using a targeted probiotic supplement when addressing specific health concerns.

Fermented vs. Probiotics: Unpacking the Misconception

Many assume that eating fermented foods is the same as consuming probiotics, but this is a common nutritional misconception. While all probiotic products are technically fermented, not all fermented foods contain probiotics. The key distinction lies in the scientific validation and controlled quantity of specific microbial strains.

What are Fermented Foods?

Fermented foods are produced through a process where microorganisms like yeast and bacteria convert carbohydrates into alcohol or acids. This process adds flavor and texture and acts as a natural preservative. Examples include yogurt, kefir, sauerkraut, kimchi, and kombucha.

Key Characteristics of Fermented Foods:

Diverse Microbiota: Fermented foods have a varied microbial makeup depending on the process and ingredients.
Uncertainty of Strains and Quantity: The specific strains and number of live microbes are often not guaranteed, especially if pasteurized.
Nutritional Enhancement: Fermentation can improve nutrient bioavailability and aid digestion.
Culinary and Nutritional Benefits: These foods are part of many traditional diets and provide vitamins and minerals.

What are Probiotics?

Probiotics are live microorganisms that provide a documented health benefit when consumed in adequate amounts. They are typically found in supplements or fortified foods and are defined by their proven health effects, not just the fermentation process.

Key Characteristics of Probiotics:

Specific Strains: Probiotics contain specific, clinically researched bacteria or yeast strains with proven health benefits.
Guaranteed Viability: Products ensure a guaranteed number of live organisms (CFUs) remain viable.
Targeted Health Benefits: Benefits are strain-specific, addressing issues like antibiotic-associated diarrhea or supporting the gut-brain axis.
Higher Concentration: Supplements offer a much higher concentration of beneficial microbes than typical fermented foods.

Comparison: Fermented Foods vs. Probiotic Supplements


Feature	Fermented Foods	Probiotic Supplements
Definition	Foods/drinks made via microbial growth.	Live microorganisms conferring health benefits in adequate amounts.
Microbial Composition	Diverse, variable, often undefined mix of microbes.	Specific, identified, clinically validated strains.
Dose & Potency	Inconsistent microbial counts.	High-concentration, consistent dose (CFUs) with clinical evidence.
Targeted Benefits	General gut support, less specific effects.	Targeted, specific health outcomes based on research.
Manufacturing Process	Fermentation; can be pasteurized.	Produced to guarantee viability and dose; often shelf-stable.
Example Products	Sauerkraut (raw), kefir, kombucha, kimchi, some yogurts.	Capsules, powders, fortified dairy.

Are Fermented Foods or Probiotics Better?

It's not about choosing one over the other; both can contribute to gut health.

Why Consume Fermented Foods?

Fermented foods introduce a variety of beneficial bacteria and are rich in nutrients, fiber, and prebiotics, supporting overall gut wellness. However, they aren't ideal for targeting specific health issues due to inconsistent microbial content.

When to Consider Probiotic Supplements?

Supplements offer a targeted approach for specific health concerns, providing a controlled dose of clinically studied strains for issues like diarrhea or immune support. They are also convenient for those with limited access to fresh fermented foods.

How to Combine Both for Optimal Benefits

For a balanced approach:

Eat Diverse Fermented Foods: Regularly include items like raw sauerkraut, kefir, and kimchi.
Use Targeted Supplements: Consult a healthcare provider for a supplement with a clinically proven strain if addressing a specific issue.
Check Labels: Look for "live and active cultures" in foods and specific strains and CFU counts in supplements. ISAPP provides helpful guidance.

Conclusion

The key difference between fermented foods and probiotics lies in scientific validation and dosage. Fermented foods offer broad, variable microbial and nutritional support, while probiotics provide specific, concentrated doses of clinically proven microbes for targeted benefits. Understanding this helps in making informed decisions for a healthy gut.

Frequently Asked Questions

No, not all fermented foods are probiotics. For a food to be called a probiotic, it must contain a sufficient number of specific, live microorganisms that have been clinically shown to provide a health benefit. Many fermented foods do not meet these strict criteria.

Yes, pasteurization involves heating the food to a high temperature, which kills the live bacteria present. Many commercial fermented products are pasteurized for a longer shelf life, so it's important to look for products labeled as 'raw' or with 'live and active cultures' to ensure probiotic benefits.

Yogurt is a fermented food, but it is not automatically a probiotic. To be considered a probiotic, it must contain a specific, clinically validated strain of bacteria in a sufficient dose, as indicated by a label like 'live and active cultures'.

Both can be beneficial. Fermented foods offer general support by introducing a diverse range of microbes along with other nutrients. Probiotic supplements offer a targeted, high-dose approach for specific health concerns. The best approach often involves a combination of both.

For some individuals, especially those with sensitive digestive systems, introducing fermented foods too quickly can cause temporary bloating or discomfort. It is best to start with small quantities and gradually increase your intake to allow your body to adjust.

Look for products that clearly list the genus, species, and strain (e.g., Lactobacillus rhamnosus GG) on the label. High-quality probiotic supplements will provide this specific information, unlike many fermented foods where the strains are variable and not specified.

No, a single serving of fermented food generally does not contain the same high concentration of targeted, clinically proven bacteria as a quality probiotic supplement. You would need to consume a very large quantity of fermented food to match the dose of one supplement capsule.