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Unless you happen to know a lot about the makeup of milk kefir and yogurt, they might seem like very similar dairy products.

However, there are several differences between kefir and yogurt. Knowing more about the composition of kefir versus yogurt can help better inform you on which you can likely derive the most benefits from.

Probiotics Found In Kefir

Kefir is a fermented milk drink similar in consistency to a yogurt drink. It’s made with kefir grains that resemble cottage cheese and contain bacteria and yeast.

Kefir originated in Eurasia and the Caucasus, but is now quite popular globally as a healthy drink easily made at home.

Bacteria found in kefir may have the ability to colonize the gastrointestinal tract, although researchers are still investigating this. It also contains various beneficial yeast strains.

As a result, kefir offers some health benefits, and when regularly consumed can offer long-term health benefits. This makes kefir a great probiotic for people who suffer from a range of gastrointestinal disturbances due to dysbiosis.

It also makes kefir a great probiotic for general health promotion.

Bacteria and yeast strains that are most commonly found in kefir are:

Bacteria Strains

  • Lactobacillus acidophilus
  • Lactobacillus brevis
  • Lactobacillus casei
  • Lactobacillus delbrueckii
  • Lactobacillus helveticus
  • Lactobacillus kefiranofaciens
  • Lactobacillus kefiri
  • Lactobacillus paracasei
  • Lactobacillus plantarum
  • Lactobacillus rhamnosus
  • Lactobacillus sake
  • Lactococcus lactis
  • Streptococcus thermophilus

Yeast Strains

  • Candida humilis
  • Kazachstania unispora
  • Kazachstania exigua
  • Kluyveromyces siamensis
  • Kluyveromyces lactis
  • Kluyveromyces marxianus
  • Saccharomyces cerevisiae
  • Saccharomyces martiniae
  • Saccharomyces unisporus

Probiotics Found in Yogurt

Yogurt contains several beneficial bacteria species, but far less than what is found in kefir. The species found in yogurt vary depending on the type and brand consumed.

The bacteria strains often found in yogurt are typically live and active cultures such as:

  • Lactobacillus bulgaricus
  • Streptococcus thermophilus
  • Bifidobacterium lactis
  • Lactobacillus acidophilus
  • Lactobacillus delbrueckii



Milk kefir is cultured dairy produced by the fermentation of milk by lactic acid bacteria, as well as yeasts, derived from kefir grain. (Bourrie, Willing, & Cotter, 2016)

It is associated with a wide range of health benefits such as:

  • Cholesterol metabolism
  • Antimicrobial activity
  • Tumor suppression
  • Wound healing
  • Increased immune system defense and health

Kefir is a mesophilic culture. It cultures at room temperature with no special equipment and can be cultured by using a reusable or single-use culture.

In order to keep milk kefir grains optimally functioning they have to be transferred to fresh milk every 24 hours. Single-use cultures are manufactured in a lab, contain fewer strains of bacteria, and a new packet must be used each time a new batch is made.

Kefir can be tart or sour and has a slight yeasty taste. This is in part due to the beneficial yeasts it contains. However, the taste of kefir can be altered based on how long it is fermented.

Kefir has a more liquid consistency than yogurt, making it easier to drink.


Yogurt is a popular cultured dairy product obtained by fermentation of milk-specific microorganisms. Consuming yogurt regularly is associated with several health benefits including:

  • Improved digestive health
  • Improved immune system functioning and defenses
  • Protection against heart disease
  • Protection against osteoporosis  
  • Potential antioxidant and anti-inflammatory activity

(Yoon, Ahn, Jhoo, & Kim, 2019)

Yogurt is derived from two types of yogurt starters: mesophilic and thermophilic.

  • Mesophilic is yogurt cultured at room temperature.
  • Thermophilic is yogurt that is heat-loving. This means equipment is needed to ferment yogurt at a consistent temperature. The bacteria used is a bile-sensitive species of lactic acid bacteria. (Morelli, 2014)

These yogurt starters often come in the form of reusable and single-use cultures. Reusable yogurt starters are used by mixing previously made yogurt into fresh milk. Once the new batch is finished it then becomes the starter for the next round.

Yogurt cultures must be re-cultured once a week, if not more. Single-use cultures are typically in powdered form. Each time yogurt is made, a new packet of starter cultures must be used. When the yogurt is finished it is either mild or tangy in taste and is thick in consistency.

Yogurt Recommendations

Several commercial yogurts are available featuring well-researched probiotic strains known to produce beneficial health effects - these include Activia, Vaalia and Nancy’s.

Which Is Best?

Both cultured dairy products offer several great health benefits. If what you need is more probiotic strains, then kefir is likely the best choice out of the two. This is because it contains the most strains of beneficial yeasts as well as bacteria.

Keep in mind that there is a difference between using powder and kefir grains. Kefir grains will always contain more beneficial bacteria. Also, homemade kefir may contain more strains of probiotic bacteria than kefir that is purchased from the store does. Quality of the milk used may also play an important role in its health benefits.

As for yogurt, yogurt cultures differ and species of beneficial bacteria can vary, as well. Yogurt also contains far fewer bacteria than kefir does. Depending on your needs — such as if you are starting on probiotics or have a health condition where too many probiotics may not be ideal — then yogurt is a great source of probiotic bacteria.

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Research Citations

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