Understanding Your Probiotics: Which Yogurt Has L. reuteri?

October 4, 2025 •

5 min read

While many yogurts claim to be probiotic-rich, most store-bought varieties do not contain the specific strain L. reuteri. The answer to which yogurt has L. reuteri? is rarely found in the grocery aisle, as the most effective method involves a specialized homemade fermentation process.

Quick Summary

The highly-concentrated probiotic L. reuteri is not typically available in commercial yogurts. Creating a potent, fermented dairy product requires using specific probiotic tablets or sachets along with a long, low-temperature incubation period.

Key Points

Commercial options are limited: Store-bought yogurts, with the possible exception of some older Stonyfield varieties, do not typically contain L. reuteri, especially not in therapeutic quantities.
Homemade is the primary method: High-potency L. reuteri fermented dairy is most effectively made at home using specific starter cultures and a special process, as popularized by Dr. William Davis.
Specialized ingredients are required: Creating this fermented dairy product needs a source of specific L. reuteri strains (e.g., BioGaia Gastrus) and prebiotic fiber (like inulin).
Long, low-temperature fermentation is key: Unlike standard yogurt, homemade L. reuteri fermentation requires 30-36 hours of incubation at a consistent temperature of around 100°F (~37.7°C).
Benefits include potential mood and skin improvement: Beyond general gut health, the high concentration of L. reuteri can increase oxytocin levels, which has been linked to improved skin and mood.
Consistency may vary: Due to the natural fermentation process without stabilizers, the final product's texture can be thin or separated, which is normal and does not indicate failure.

Commercial Yogurt vs. Homemade Fermented Dairy

For those seeking the specific health benefits associated with L. reuteri, simply purchasing a regular probiotic yogurt is unlikely to be sufficient. The probiotic, also known as Limosilactobacillus reuteri, was largely lost from the modern human gut due to lifestyle changes. The standard yogurt-making process, which uses different bacterial strains and shorter fermentation times, is not designed to produce the high concentrations of L. reuteri needed for therapeutic effects.

Historically, one commercial brand, Stonyfield, was noted to have a product containing L. reuteri. However, this information may be outdated, and the bacterial count would likely be much lower than that of a specially prepared homemade version. For this reason, enthusiasts of high-potency L. reuteri fermented dairy turn to the DIY method, championed by cardiologist Dr. William Davis.

The DIY Method for L. reuteri Fermented Dairy

Making a therapeutic, high-potency L. reuteri yogurt requires specific ingredients and conditions that differ from traditional yogurt-making. This process allows the targeted L. reuteri strains to proliferate to extremely high concentrations, potentially reaching trillions of colony-forming units (CFUs) per serving.

Key Ingredients and Equipment

Starter Culture: Probiotic tablets or sachets containing the specific L. reuteri strains ATCC PTA 6475 and DSM 17938, such as BioGaia Gastrus. Other starter cultures may contain different strains or be less concentrated.
Prebiotic Fiber: Inulin powder or unmodified potato starch provides a food source for the L. reuteri to multiply.
Dairy Base: Whole cow's milk, half-and-half, or cream is typically used. Ultra-pasteurized dairy is often recommended to prevent contamination from other bacteria. For dairy-free versions, additive-free coconut milk can be an option.
Yogurt Maker or Incubator: A device capable of holding a stable temperature of around 100°F (37.7°C) for up to 36 hours is crucial, as the L. reuteri strains thrive at this specific lower temperature.

The Fermentation Process

Preparation: In a sterilized jar, mix the crushed probiotic tablets or starter culture with the prebiotic fiber and a small amount of milk to form a slurry.
Combination: Mix the slurry with the remaining milk. Using a whisk is fine, but avoid aggressive blending that can damage the live bacteria.
Incubation: Place the mixture in a yogurt maker set to approximately 100°F (37.7°C) and ferment for 30-36 hours. This long, cool fermentation is key to achieving high probiotic counts.
Cooling and Storage: After fermentation, refrigerate the finished product for several hours to set. Reserve a portion to use as a starter for future batches.

Benefits and Considerations of L. reuteri Yogurt

The benefits of consuming a high-potency, homemade L. reuteri product extend beyond general gut health. Research has linked the specific strains used in this fermentation to potential improvements in mood and skin quality, partly due to its ability to increase levels of the 'feel-good' hormone oxytocin. Other potential advantages include appetite control, boosted immunity, and digestive support.

However, it's important to note the differences between this homemade fermented dairy and regular yogurt. The consistency can be inconsistent, sometimes runny or with separated whey, especially in the first batch. This is a natural result of the prolonged fermentation without added thickeners. The probiotic manufacturers themselves have stated their strains were not designed for yogurt-making, so results can vary.

Comparison Table: Homemade L. reuteri vs. Commercial Yogurt


Feature	Homemade L. reuteri Fermented Dairy	Commercial Probiotic Yogurt
Probiotic Count	Very high, in the trillions CFU range	Moderate to low; specific CFU not always listed
Strains	Specific, therapeutically-researched strains (e.g., ATCC PTA 6475, DSM 17938)	A variety of common probiotic strains, often not including therapeutic levels of L. reuteri
Fermentation	Long and low-temperature (30-36 hours at ~100°F)	Shorter, higher-temperature fermentation
Ingredients	Requires starter culture, prebiotic fiber, dairy/coconut milk	Contains typical yogurt starter, milk, and often sugars or thickeners
Consistency	Often thinner, potentially separated, with a distinct tangy taste	Typically thick and creamy due to stabilizers and additives
Availability	Requires DIY preparation with specific ingredients	Widely available in grocery stores

Conclusion: Navigating Your Probiotic Options

For those seeking the specific health benefits of high-dose L. reuteri, the most reliable path is the homemade fermented dairy method rather than searching for a specific commercial product. While this requires a bit more effort and specialized ingredients like BioGaia starter tablets and prebiotic fiber, it provides the control necessary to achieve a therapeutically potent food. Most commercial yogurts, with their standard formulations, are not designed to deliver the same level of concentrated probiotic activity. By understanding this distinction, consumers can make informed choices about how to best incorporate L. reuteri into their nutrition diet for optimal gut health.

Can commercial yogurt be used as a starter for L. reuteri yogurt?

No, because commercial yogurts do not contain the specific strains of L. reuteri (ATCC PTA 6475 and DSM 17938) required for the high-potency fermentation.

What are the main benefits of consuming L. reuteri fermented dairy?

Consuming a high-concentration L. reuteri product is associated with improved gut health, enhanced immune function, increased oxytocin production, and potential benefits for skin and mood.

Is homemade L. reuteri yogurt guaranteed to work every time?

No, even with the right ingredients, results can be inconsistent. Factors like the quality of the ingredients, fermentation temperature, and incubation time can affect the outcome.

Why is the fermentation time so long for L. reuteri yogurt?

The long 30-36 hour fermentation period at a lower temperature (~100°F) is necessary for the L. reuteri bacteria to proliferate to the high concentrations needed for therapeutic effect.

What is the purpose of adding prebiotic fiber to L. reuteri yogurt?

The prebiotic fiber, such as inulin or potato starch, acts as food for the L. reuteri bacteria, helping them to multiply and produce a high-concentration probiotic product.

Can you re-culture homemade L. reuteri yogurt indefinitely?

It is not recommended to re-culture indefinitely. To maintain the purity and potency of the L. reuteri strains, it's best to start a fresh batch with new tablets after 4-5 re-inoculations.

Why does BioGaia state their products were not designed for yogurt-making?

BioGaia confirms their probiotics were not developed for fermentation, but rather for direct ingestion in tablets. The homemade fermentation method is a creative application by users to amplify the probiotic count beyond what a single tablet provides.

Frequently Asked Questions

No, you must use a supplement containing the specific L. reuteri strains ATCC PTA 6475 and DSM 17938, such as BioGaia Gastrus. Most probiotic capsules contain different strains not suitable for this fermentation process.

No. Most commercially available yogurts use other bacteria for fermentation. Finding a product containing L. reuteri on store shelves is rare, and the concentration would be significantly lower than a homemade version.

You need a yogurt maker or another device that can maintain a consistent temperature of around 100°F (37.7°C) for 36 hours. Many modern yogurt makers or Instant Pots with a custom yogurt function work well.

The prebiotic fiber, such as inulin, provides nourishment for the L. reuteri bacteria, allowing them to multiply rapidly during the long fermentation period and achieve a high probiotic count.

The long, low-temperature fermentation is specifically optimized for the growth of L. reuteri strains, ensuring they reach a potent, therapeutic concentration. Traditional yogurt uses a shorter, hotter process that would not achieve the same result.

Yes, especially during the first batch. This is a common and normal result of the fermentation process without added stabilizers. Both the solid curds and liquid whey contain the beneficial bacteria and can be consumed.

Homemade L. reuteri fermented dairy offers a vastly higher concentration of specific, clinically studied probiotic strains. Store-bought yogurts typically have lower, variable probiotic counts and may contain different strains that offer general rather than targeted health benefits.

A successful batch will have a pleasant tangy taste and will ferment into a dairy product, even if the consistency is thin or separated. The therapeutic effects are tied to the fermentation time and correct ingredients, rather than a specific thick texture.