What food has the most L. reuteri?

November 18, 2025 •

4 min read

While many assume store-bought yogurt is a top source, commercially available fermented foods contain inconsistent and often low amounts of this potent probiotic. For maximizing intake, specialized homemade L. reuteri yogurt is the most potent food source available.

Quick Summary

Specialized homemade yogurt fermented with specific L. reuteri strains offers the highest concentrations, surpassing levels found in typical fermented foods like sauerkraut or kimchi, and providing a powerful source of this probiotic.

Key Points

Homemade L. reuteri yogurt is the most potent source: Specialized homemade yogurt, fermented for 24-36 hours with specific L. reuteri strains and prebiotic fiber, offers the highest concentrations.
Commercial foods are unreliable: Most store-bought yogurts and fermented foods contain different, inconsistent, and often lower concentrations of L. reuteri.
Strain specificity is crucial: The health benefits associated with L. reuteri are strain-dependent; therapeutic effects come from specific strains like DSM 17938 and ATCC PTA 6475, not generic lactobacilli.
Supplements offer precision: Probiotic supplements provide a reliable and consistent dose of specific L. reuteri strains, addressing deficiencies in the modern diet.
Dietary diversity supports the microbiome: Including a variety of fermented foods and prebiotics can support a healthy overall gut microbiome, which can in turn foster the growth of native L. reuteri.
Not all fermented foods are equal: While some traditional fermentations like sauerkraut might contain L. reuteri, commercial versions are often pasteurized, destroying the beneficial bacteria.
Breast milk is a natural source: Historically, L. reuteri was prevalent in breast milk, underscoring its natural presence in humans before the modern era.

The Challenge of Finding L. reuteri in Everyday Foods

Unlike more common probiotics, the Limosilactobacillus reuteri strain is not widely or consistently available in mass-produced food products. While it was once prevalent in the human gut, modern diets and antibiotic use have caused its numbers to decline significantly. The L. reuteri found in sources like breast milk, for instance, is naturally abundant, highlighting the importance of specific preparation methods to regain high concentrations in our diets. Relying solely on general fermented foods will likely not provide the specific therapeutic dose of L. reuteri needed for noticeable effects.

Why Homemade Yogurt with Specific Strains is the Top Source

The most effective and widely publicized method for consuming large amounts of L. reuteri is through specialized homemade yogurt. This is not your standard kitchen yogurt; it requires a specific starter culture (often containing strains like DSM 17938 and ATCC PTA 6475) and a precise, long fermentation process. The process typically involves adding prebiotic fibers like inulin to the milk to provide food for the bacteria, and fermenting the mixture for 24 to 36 hours at a low, controlled temperature (around 100°F or 38°C). This long, nutrient-rich fermentation allows the bacteria to multiply exponentially, creating a product with a far higher probiotic count than any commercially available alternative.

Other Fermented and Plant-Based Sources

While not as concentrated or reliable, other foods can contain L. reuteri, depending heavily on the preparation method and ingredients. These sources may offer some benefit for overall gut diversity, but should not be relied upon for targeted L. reuteri supplementation.

Certain cheeses: Some aged, traditional cheeses like Parmigiano Reggiano have been shown to contain L. reuteri, though concentrations vary widely.
Sourdough bread: The wild fermentation process of sourdough bread can harbor various lactobacilli, including L. reuteri, although the presence is not guaranteed and counts are lower than in targeted preparations.
Fermented vegetables: Traditional sauerkraut and kimchi, if prepared correctly without pasteurization, may contain L. reuteri. However, commercial versions are often pasteurized, and the specific strains are inconsistent.
Plant-based carbohydrates: Some plant-based foods, such as beans, sweet potatoes, and artichokes, are believed to support a healthy gut microbiome, which can, in turn, encourage the growth of native L. reuteri.

Natural Food vs. Supplements

When considering how to increase your L. reuteri intake, it's important to weigh the pros and cons of obtaining it from food versus supplements. The ideal choice depends on your specific health goals, convenience, and tolerance for dietary changes.


Feature	Specialized Homemade L. reuteri Yogurt	Commercial Fermented Foods	L. reuteri Probiotic Supplements
Potency	Highest, with billions of CFUs per serving due to controlled fermentation.	Highly variable and often low; quality depends on fermentation method and processing.	High and standardized; CFUs are listed on the label for precise dosage.
Consistency	Highly consistent if made with the same starter and method.	Inconsistent due to variations in fermentation, ingredients, and storage.	Guaranteed consistency and stability from batch to batch.
Convenience	Requires time, effort, and specific equipment for incubation.	Ready-to-eat but unreliable for specific strains or counts.	Easy to take; available in capsule, powder, or chewable forms.
Strain Specificity	Guarantees specific, proven strains (e.g., DSM 17938, ATCC PTA 6475).	Unpredictable; specific strains are rarely listed or guaranteed.	Specific strains are always identified on the product label.
Cost	High initial investment for starter culture and equipment, but cost-effective per serving over time.	Relatively low cost, but may not deliver the therapeutic dose desired.	Higher per-serving cost compared to homemade yogurt, but no initial setup cost.

The Importance of Strain Specificity

It is critical to understand that the benefits of L. reuteri are strain-specific. For example, studies on gut health, immune function, and mental well-being often use specific, patented strains like DSM 17938 or ATCC PTA 6475. These are the strains typically used in starter cultures for making the potent homemade yogurt. Generic lactobacilli found in many standard yogurts are not the same and will not produce the same results.

How to Create the Most Potent Source

To create a truly potent source of L. reuteri, follow these steps:

Gather ingredients: You will need high-quality dairy milk or half-and-half, a prebiotic fiber powder (such as inulin), and a specific starter culture containing the desired L. reuteri strains.
Combine ingredients: Heat the milk gently and then mix in the prebiotic fiber and the L. reuteri starter culture according to the manufacturer's instructions.
Incubate for an extended period: The key to achieving high bacterial counts is a long, low-temperature fermentation. Use a dedicated yogurt maker or sous vide machine to maintain a consistent temperature of around 100°F (38°C) for 24 to 36 hours. This prolonged incubation allows the bacteria to proliferate extensively.
Cool and store: After fermentation, the yogurt should be stored in the refrigerator. It can then be used to culture subsequent batches, making the process more cost-effective over time.

A Broader Approach to Gut Health

For those not interested in the specific, high-potency L. reuteri yogurt, focusing on general fermented foods and prebiotics can still provide benefits for overall gut microbiome diversity. A diverse diet rich in fiber from whole grains, fruits, and vegetables can support the natural growth of beneficial bacteria already present in your gut.

Conclusion

While L. reuteri can be found in some traditional fermented foods and dairy products, the concentration is often low and inconsistent. The most reliable and potent food source is undoubtedly specialized homemade L. reuteri yogurt, which is fermented for an extended period using specific strains and prebiotic fibers. For those seeking therapeutic levels of this important probiotic, targeted supplementation or this specific homemade preparation is necessary. Ultimately, restoring this valuable microbe to the diet can have significant, positive impacts on digestive and overall health.

Visit Revolution Fermentation for a detailed L. reuteri yogurt recipe.

Frequently Asked Questions

No, most conventional store-bought yogurts do not contain therapeutic levels of specific L. reuteri strains. They typically contain other, more common strains of bacteria, and their bacterial count is often much lower than what is achieved through specialized fermentation.

To make L. reuteri yogurt, you need a specific starter culture containing strains like DSM 17938 or ATCC PTA 6475, milk, and prebiotic fiber. The mixture is incubated for 24 to 36 hours at a low, stable temperature (around 100°F) using a yogurt maker or similar device to maximize bacterial growth.

L. reuteri is primarily associated with dairy fermentation, but some plant-based foods like traditionally fermented vegetables (e.g., sauerkraut, kimchi) or certain carbohydrates (beans, artichokes) may contain it or support its growth, although levels are unreliable.

The prevalence of L. reuteri in the human gut has declined due to modern diets high in processed foods, the use of antibiotics, and other environmental factors that disrupt the natural microbiome.

No, while supplements offer a highly concentrated and consistent dose, you can obtain therapeutic levels from homemade L. reuteri yogurt. For those seeking convenience or precise dosing, a supplement is a reliable alternative.

Adding prebiotic fiber, such as inulin, to the yogurt serves as food for the L. reuteri bacteria, helping them to multiply more vigorously during the long fermentation process. This results in a significantly higher and more potent bacterial count in the final product.

The extended 24- to 36-hour fermentation period, combined with a lower temperature, allows the L. reuteri cultures enough time to multiply and reach the very high bacterial concentrations needed to achieve the desired health benefits, a level far beyond what is found in conventional yogurt.