Does Kefir Have Lactobacillus Rhamnosus GG? An In-depth Probiotic Comparison

November 19, 2025 •

4 min read

While kefir is renowned for its diverse microbial content, boasting up to 60 different strains of bacteria and yeast, it does not naturally contain the specific, patented strain known as Lactobacillus rhamnosus GG (LGG). The presence of this well-researched probiotic in a kefir product depends entirely on whether it has been added by the manufacturer.

Quick Summary

Traditional kefir is a source of many varied probiotic species, but it does not naturally include the LGG strain. The patented LGG strain, known for specific health benefits, is typically found in specialized supplements or added to certain commercial dairy products, separate from the indigenous cultures in kefir grains.

Key Points

LGG is not a natural component: The specific Lactobacillus rhamnosus GG strain is not found in the natural, traditional microbial cultures of kefir grains.
LGG can be added to kefir: For a product to contain LGG, the strain must be intentionally added by the manufacturer, typically in commercial formulations.
Kefir has diverse natural cultures: Traditional kefir provides a broad spectrum of beneficial bacteria and yeasts, offering wide-ranging support for gut health.
Check the product label: To confirm the presence of the specific LGG strain, consumers must read the ingredients list, as standard kefir does not guarantee its inclusion.
LGG is a target strain: Unlike the general probiotic benefits of kefir, LGG is known for specific, clinically-researched effects, such as improved intestinal wall adhesion.
Supplements are a reliable source for LGG: For those seeking the specific benefits of LGG, dedicated probiotic supplements or intentionally fortified products are the most dependable sources.

Kefir vs. Lactobacillus rhamnosus GG: Understanding the Distinction

While both kefir and Lactobacillus rhamnosus GG (LGG) are celebrated for their health-promoting properties, they represent fundamentally different probiotic options. Traditional kefir is a complex, symbiotic community of bacteria and yeasts known as kefir grains, which produce a wide array of microbial species. In contrast, LGG is a single, scientifically-isolated strain with well-documented, specific health benefits. The key takeaway is that consumers seeking the benefits of LGG should not assume it is present in standard kefir and must check product labels carefully.

The Diverse World of Traditional Kefir

Traditional kefir is produced by fermenting milk or sugar water with a culture of bacteria and yeasts, known as kefir grains. This fermentation process creates a beverage with a rich and varied microbial ecosystem. The exact composition of kefir grains can differ based on their geographical origin, fermentation time, and the substrate used, but they typically contain a mix of bacteria and yeast species. Common bacterial genera found include Lactobacillus, Lactococcus, Streptococcus, and Leuconostoc, along with yeasts like Saccharomyces and Kluyveromyces. This diversity is what makes kefir a powerhouse of probiotics, supporting overall gut health and digestion.

The Specific Science of Lactobacillus rhamnosus GG

LGG is a specific, patented probiotic strain of Lacticaseibacillus rhamnosus (formerly Lactobacillus rhamnosus). Isolated from the human gut in 1983, it has become one of the most extensively studied and commercially available probiotic strains worldwide. Unlike the broad spectrum of microbes in traditional kefir, LGG offers targeted benefits backed by decades of clinical research. Its specific properties include the production of adhesive pili (fimbriae), which help it stick to and colonize the intestinal wall more effectively than many other strains. This colonization is crucial for its beneficial effects on the host's health, particularly its proven ability to prevent and treat various types of diarrhea.

Is LGG Ever Found in Kefir?

While LGG is not an inherent part of the natural kefir grain culture, it can be purposefully added during production. For example, scientific studies have shown that LGG can be successfully added to kefir as a carrier probiotic, maintaining its viability and adding its specific benefits to the final product. In fact, some commercial kefir products, such as those from Lifeway, list Lactobacillus rhamnosus among their probiotic cultures. However, unless the label specifically designates the GG strain, consumers cannot be certain they are receiving this particular patented microbe. When purchasing kefir, it is important to read the ingredients list to see if a specific strain like LGG has been included as a separate additive or if the product relies solely on the natural diversity of the kefir grains.

Accessing LGG vs. Kefir's Probiotics

For those specifically seeking the clinically-proven benefits of LGG, relying solely on kefir is unreliable unless the product is specifically fortified and labeled. Here are the most common ways to access these different probiotics:

For LGG: The most reliable method is through probiotic supplements that list LGG prominently on the label. It is also found in some yogurts and dairy products where it has been added for its specific health properties.
For Kefir's Probiotics: These are best obtained from traditional, unflavored kefir made from live kefir grains. The diverse, natural cultures contribute to the overall gut microbiome. Opting for unsweetened versions is advisable to avoid excessive sugar.

Comparison Table: Traditional Kefir vs. Lactobacillus rhamnosus GG


Feature	Traditional Kefir	Lactobacillus rhamnosus GG (LGG)
Microbial Composition	Diverse mix of bacteria and yeast species (e.g., Lactobacillus, Lactococcus, Saccharomyces, Kluyveromyces)	A single, specific bacterial strain of Lacticaseibacillus rhamnosus
Natural Source	From a symbiotic culture of bacteria and yeasts (SCOBY), known as kefir grains	Isolated from the healthy human gastrointestinal tract
Mechanism of Action	Broad effects due to diverse population, including antimicrobial properties and immune modulation	Known for superior intestinal wall adhesion via pili and specific immunomodulatory effects
Common Forms	Fermented dairy drink, homemade with grains	Supplements, fortified dairy products, and specialized food products
Application in Kefir	The base culture that creates traditional kefir	Can be added by manufacturers to commercial kefir as a carrier probiotic

Conclusion

In short, traditional kefir does not naturally contain Lactobacillus rhamnosus GG (LGG). While the generic Lactobacillus rhamnosus species may be present in the diverse mix of bacteria that make up kefir grains, the specific GG strain is patented and must be deliberately added to a product. Kefir is an excellent source of a broad range of probiotic cultures, offering diverse benefits for gut health. For those seeking the targeted, well-researched effects of LGG—such as treating diarrhea or improving gut barrier function—probiotic supplements or specific fortified products are the most reliable options. Always check the label to know exactly which probiotic strains you are consuming.

For further reading on the specific mechanisms and benefits of LGG, the NIH offers a comprehensive review of its capabilities: Towards a better understanding of Lactobacillus rhamnosus GG.

Key takeaways

No Natural LGG in Kefir: Traditional kefir, made from kefir grains, does not inherently contain the specific Lactobacillus rhamnosus GG (LGG) strain.
LGG is a Specific Strain: LGG is a patented probiotic known for its strong adhesion to intestinal walls and targeted health benefits, isolated decades ago.
Kefir has Diverse Probiotics: Traditional kefir offers a wide range of microbial species, including various Lactobacillus and yeast cultures, providing broad-spectrum benefits for the gut.
LGG Can Be Added: Some commercial kefir is fortified with LGG, so it's important to check product labels for specific strain information.
Choose Based on Goal: Choose traditional kefir for a diverse probiotic intake or opt for supplements and fortified products clearly labeled with LGG for its specific, research-backed advantages.

Frequently Asked Questions

Lactobacillus rhamnosus is a species of bacteria. LGG is a specific, patented strain of that species that has undergone extensive clinical study. The 'GG' refers to the scientists who first isolated it.

Not necessarily. Unless the label explicitly states the 'GG' strain, you cannot be certain it contains the specific, patented LGG probiotic. Some products may use a different, generic strain of L. rhamnosus.

The LGG strain is well-known for its ability to prevent and treat various forms of diarrhea, aid overall gut health by strengthening the intestinal barrier, and modulate the immune system.

Traditional kefir contains a diverse range of bacteria and yeasts from the kefir grains. This includes species such as Lactobacillus kefiranofaciens, Lacticaseibacillus paracasei, and yeasts like Saccharomyces cerevisiae, among many others.

The better choice depends on your specific health goals. Kefir provides a wider variety of probiotic species, while an LGG supplement offers a targeted, research-backed dose of a specific strain. For targeted benefits like treating diarrhea, an LGG supplement might be more effective.

Yes, some studies show that LGG can be added to kefir cultures as a carrier probiotic. However, this is typically done in controlled industrial settings to ensure viability. It is more straightforward to use a reliable LGG supplement.

Studies have shown that adding LGG to kefir can affect certain qualities, such as flavor profile due to increased acidity, but overall acceptability is often maintained. Viscosity and texture may also change slightly.