What the Kefir is in Kefir?

A reader message me about Kefir. My usual response is “You do not know what you are getting”. While for a person with near normal health, it likely does some good (keeping with the concept of hygiene hypothesis), this is not so clear for more severe dysbiosis of the gut.

“Kefir grains consist of complex symbiotic mixtures of bacteria and yeasts, and are reported to impart numerous health-boosting properties to milk and water kefir beverages. ” [2022]

Which bacteria could be in Kefir

Typical Kefir Label – What are these cultures?

There is no legal requirement to report the name of the bacteria in the kefir, nor the genus, species or strains. Each batch may have a significantly different mixture of bacteria. You want live and active cultures? Go to the forest and eat a spoonful of dirt!!

What has been seen in Kefir?

From this study: A Big World in Small Grain: A Review of Natural Milk Kefir Starters, 2020 we see the following reported:

  • Acetobacter
    • pasteurianus
    • not classified species
  • Dekkera
    • anomalus
    • bruxellensis [2022]
  • Enterobacter
    • not classified species
  • Kazachstania
    • exigua
    • not classified species
  • Kluyveromyces
    • marxianus
  • Lactobacillus
    • amilovorus
    • buchneri
    • crispatus
    • helveticus
    • kefiranofaciens
    • kefirgranum
    • kefiri
    • mesenteroides
    • mali [2022]
    • nagelii [2022]
    • otakiensis
    • parabuchneri
    • paracasei [2022]
    • parakefiri
    • rhamnosus [2022]
    • sunkii
  • Lactococcus
    • lactis
  • Lentilactobacillus
  • Leuconostoc 
    • pseudomesenteroides [2022]
    • not classified species
  • Liquorilactobacillus
  • Nauvomozyma
    • not classified species
  • Oenococcus
  • Saccharomyces
    • cerevisiae
    • not classified species

And the list grows every year (look at the number of 2022 citations above).

Water vs Milk Kefir?

” in this study, the variety of WK grain microbial consortia was wider than that of MK grains, and this significantly affected the resultant WK products.” Water kefir grains vs. milk kefir grains: Physical, microbial and chemical comparison [2022]

And from A comparison of milk kefir and water kefir: Physical, chemical, microbiological and functional properties [2021] “The two different fermented beverages produced from these grains have different physical and chemical characteristics and different microbiological composition.”

From Milk Kefir to Water Kefir: Assessment of Fermentation Processes, Microbial Changes and Evaluation of the Produced Beverages [2022] ” It is indeed reported that kefir grains may adapt to new available carbon sources affecting their granulation and the microbial growth on them, as well as the microbial characteristic of the final beverage.”

Bottom Line

Kefir is not a precise product, even in the vaguest terms. I am bias to juggling as few balls at a time as possible… Kefir feels like working with all of the balls in an IKEA kids ball room. It’s spinning the barrel of a bacteria roulette — especially since the same product from the same manufacturer may be different in the next batch. For grown at home kefir, the variability will be a lot higher.

2 thoughts on “What the Kefir is in Kefir?

  1. Interesting thought which challenges the belief that the historic human biome of long ago was superior because it had a far wider spectrum of bacteria, with perhaps five to ten times the number if variants, than the typical human biome has today. What challenges this is that the vast majority of naturally occurring bacteria are in fact beneficial and it’s a small percentage of the the total that are hostile to varying degrees. What is clear is the evolution of bacteria moving from sometimes hostile towards beciming benign then moving in to being essential and then next beneficial and penultimately essential. The final condition is when they become so essential they become an incorporated component of the permanent genetic makeup. In fact a large part of the design of the body is an assembly of genetic elements which were once bacteria. So the answer to this problem is not simple. Its an ongoing process so complex it’s impossible to be definitive about

  2. Most commercial kefirs, kombuchas, etc are made from a commercial culture whose components are known and limited. Natural kefir is much more diverse.

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