What Kind of Probiotics Are in Kefir?

November 16, 2025 •

4 min read

Kefir grains, the unique starter culture for this fermented drink, contain up to 61 strains of bacteria and yeasts, making them a much richer and more diverse source of probiotics than yogurt. This complex symbiotic culture of microorganisms (SCOBY) is responsible for kefir's impressive range of health benefits.

Quick Summary

Kefir's probiotic profile is exceptionally diverse, stemming from its starter culture of complex kefir grains containing dozens of bacteria and yeast strains, unlike many other fermented products. The final beverage's microbial composition is influenced by the grain source, fermentation conditions, and milk used.

Key Points

Rich Microbial Diversity: Kefir contains a vast array of probiotic bacteria (like Lactobacillus, Lactococcus, Bifidobacterium) and beneficial yeasts (Saccharomyces, Kluyveromyces), often with dozens of unique strains.
Source is Key: The type of probiotics and their concentration depend on the starter culture; traditional kefir grains offer a far more diverse profile than powdered starter cultures used in many commercial products.
Beneficial Yeasts: Unlike yogurt, kefir includes beneficial yeasts, which contribute to its unique taste, texture, and effervescence, as well as providing additional probiotic effects.
Contains Kefiran: Traditional kefir made with grains produces a unique, biologically active polysaccharide called kefiran, which possesses anti-inflammatory and antimicrobial properties.
Enhanced Digestive Benefits: The diverse and potent probiotic content in kefir helps modulate the gut microbiome, potentially improving digestion, alleviating lactose intolerance symptoms, and boosting immune function.
Beyond Dairy: While milk kefir is most common, water kefir is a dairy-free alternative made with different grains that contain a distinct, but also diverse, set of bacteria and yeasts.

A Complex Probiotic Ecosystem

Unlike commercial products that often use a limited number of starter cultures, traditional kefir made from living kefir grains is a powerhouse of microbial diversity. These cauliflower-like grains host a complex, symbiotic relationship between numerous species of bacteria and yeast. This unique ecosystem gives kefir a far broader and more potent probiotic profile than many other cultured dairy products, including traditional yogurt.

The composition of this microbial community is highly variable and depends on factors such as the geographical origin of the grains, the type of milk used, and fermentation conditions like temperature and time. This rich biodiversity is the source of many of kefir's documented health benefits, including its potential to modulate gut microbiota and provide antibacterial and anti-inflammatory effects.

Key Bacterial Strains Found in Kefir

The bacteria in kefir are predominantly lactic acid bacteria (LAB), though acetic acid bacteria are also present. Some of the most commonly identified probiotic strains include:

Lactobacillus kefiranofaciens and L. kefiri: These are often considered specific to true kefir and are integral to the formation of the grains themselves.
Lacticaseibacillus paracasei: This strain has demonstrated beneficial properties like strong adhesion to intestinal cells and has been identified in both milk and water kefir grains.
Lactobacillus helveticus: Also found in kefir, this strain, along with others, contributes to the production of bioactive peptides during fermentation.
Lactococcus lactis: Commonly found in milk-based products, this species is a key member of the kefir grain's bacterial community.
Leuconostoc species: These bacteria contribute to the flavor and carbonation of kefir and are part of the complex culture.
Bifidobacterium species: A genus of bacteria known for its gut health benefits and its presence in kefir products.

Beneficial Yeast Strains in Kefir

In addition to bacteria, the presence of beneficial yeasts is what truly sets kefir apart from other fermented milks like yogurt. These yeasts play a crucial role in the fermentation process and offer distinct health benefits. Common yeast species in kefir include:

Saccharomyces cerevisiae: A widely known yeast species that can be isolated from both milk and water kefir grains.
Kluyveromyces marxianus: This yeast contributes to the unique organoleptic properties of kefir and has been shown to downregulate inflammatory responses.
Candida kefyr: Despite the name 'Candida,' this yeast is a beneficial component of the kefir culture, contributing to the flavor profile and symbiosis.

Kefir vs. Yogurt: A Probiotic Comparison

For consumers seeking to enhance their gut microbiome, understanding the probiotic differences between kefir and yogurt is crucial. While both are fermented dairy products, their microbial diversity and potency vary significantly.


Feature	Kefir	Yogurt
Starter Culture	Complex SCOBY known as 'kefir grains' (bacteria and yeast)	Specific bacterial strains (e.g., L. bulgaricus, S. thermophilus)
Probiotic Diversity	Contains a wider and more diverse range of bacteria and yeast strains, often 30+ species in traditional versions.	Typically contains only a few specific bacterial strains.
CFU Count	Higher colony-forming units, often in the tens of billions.	Typically lower CFU count compared to kefir.
Fermentation Byproducts	Produces a broader range of bioactive compounds, including peptides, acids, and polysaccharides like kefiran.	Produces a narrower range of metabolites compared to kefir.
Texture and Flavor	Thinner, drinkable consistency with a tart, tangy, and slightly effervescent flavor.	Thicker, creamy texture with a milder flavor.

Making Kefir vs. Store-Bought Options

The method of production significantly influences the final probiotic content of kefir. Traditional, homemade kefir made with live grains offers a more diverse and potent microbial profile compared to many commercial products. Some store-bought versions are produced using powdered starter cultures derived from grains, which results in a less diverse probiotic population. In contrast, authentic kefir grains can be reused indefinitely and produce a beverage with a full spectrum of live cultures, yeasts, and unique compounds like kefiran.

The Importance of Kefiran

Kefiran is a unique, water-soluble polysaccharide produced by the bacteria in kefir grains, especially Lactobacillus kefiranofaciens. It forms the gelatinous matrix that holds the microbial colonies together and is responsible for kefir's characteristic slimy texture. Kefiran also has its own notable health benefits, including anti-inflammatory, antimicrobial, and antioxidant properties. Commercial kefir made with powdered cultures often lacks this beneficial compound.

Conclusion

What kind of probiotics are in kefir? In short, kefir contains a uniquely complex and diverse ecosystem of beneficial bacteria and yeasts, far exceeding the probiotic content of most yogurts. This rich microbial consortium originates from the symbiotic relationship within kefir grains and is responsible for many of the beverage's health-promoting properties, including improved digestion, immune function, and potential anti-inflammatory and antibacterial effects. While commercial versions exist, making kefir at home with traditional grains ensures the highest potency and biodiversity, capturing the full range of lactobacilli, bifidobacteria, and yeasts, as well as unique compounds like kefiran. This makes kefir a powerful food for modulating the gut microbiome and supporting overall wellness.

Frequently Asked Questions

Yes, kefir typically contains a far more diverse and potent probiotic profile than yogurt. While yogurt often has only a few specific bacterial strains, traditional kefir made with grains can contain dozens of different species of bacteria and beneficial yeasts.

Kefir grains are a complex, symbiotic living culture of bacteria and yeast that can be reused indefinitely to produce new batches of kefir. Powdered starter culture, on the other hand, is a dehydrated, laboratory-created culture that is used for a limited number of batches before it weakens.

No, the probiotic content differs between milk kefir and water kefir because they are made with distinct grains. While both contain a variety of bacteria and yeasts, the specific species and their proportions vary depending on the fermentation substrate.

Kefiran is a unique, water-soluble polysaccharide produced by the symbiotic microbes in kefir grains. This compound is responsible for the drink's slimy texture and possesses health benefits such as anti-inflammatory and antimicrobial properties. It is typically only found in kefir made with authentic grains.

While store-bought kefir is still a good source of probiotics, the diversity and quantity of live cultures are often lower than in homemade versions made with traditional grains. Many commercial products use powdered starters, resulting in a less complex microbial composition.

Key bacterial species found in kefir include several Lactobacillus species (L. kefiranofaciens, L. kefiri, L. paracasei, L. helveticus), along with Lactococcus lactis, Leuconostoc, and Bifidobacterium species.

Yes, many of the probiotic strains in kefir are acid- and bile-resistant, allowing them to survive the harsh conditions of the digestive tract. This enables them to reach the intestines and potentially colonize and benefit the gut microbiome.