Given the legendary status of kefir grains and its potency, its surprising that there is not a lot of scientific data available when it comes to bacteria count. The process to bring healthy grains to the lab (without them weakening in transit), using an effective fermentation medium (one that they are adapted to), identifying individual strains and their subsequent CFU count is very daunting and expensive. And anyone who has done homemade kefir knows that there can be huge variations from day to day, season to season, so its no wonder its that hard to quantify the power of kefir. There are 3 studies that may shed some light on the probiotic count of kefir.
One study propagated around the internet originally comes from nourishingplot that states that a Florida microbiology class tested goat’s kefir from Glades Ridge Goat Dairy[1]. They found 10 billion CFU per ml (or grams which is equivalent) which comes to about 150 billion CFU per tablespoon or 2.4 trillion per cup! However, there is no link to the original study and I cannot find it anywhere.
Interesting enough, there is one official study that may partially confirm those extraordinarily high findings. It comes out of the Department of Microbiology from the Federal University of Lavras[2]. They sampled 270 milk kefir grains from all over the world. The highest CFU probiotic count was from the United States followed by Canada. The US count was 10.43 billion per CFU/g which amounts to about 150 billion per tablespoon or (2.4 trillion per cup). That number falls in line with the Glades Ridge Goat Dairy study. However, that was the highest bacteria count reported at the warmest temperature (35 degrees Celsius) and there were reports from grains that were much lower. They also fermented in an artificial MRS medium and not milk. Despite the limitations it does show the potential for a very high bacteria count.
Another official study coming out of Scotland and Poland studied 6 milk kefir samples from Iraq[3]. This time they used cows and sheep milk as the medium of fermentation. So, these results are more natural and more representative of what you would find with home fermenting. They found about 10^9 or about 1 billion CFU per gram for Lactococcus and Lactobacillus each. Other strains were insignificantly in count. Overall, that’s about 5 times less than the other two studies, but still about a 500 billion per cup. A very respectable number considering that high end expensive probiotic pills only give you about 50 billion.
Conclusion
In any case, there is no doubt that there is a large probiotic bacteria count in kefir. Just how much on average, is still being researched. The most likely scenario is that it ranges from several hundred billion to trillions per cup. If you know of more studies, please do let us know.
References:
[1] https://www.nourishingplot.com/2015/10/21/surprising-probiotic-count-of-kefir/
[2] https://www.sciencedirect.com/science/article/pii/S0963996910001493
[3] https://www.sciencedirect.com/science/article/pii/S002364380190773X
Comments
Yemoos Nourishing Cultures
Hi Caroline – Yes, the bacteria / probiotic count should increase with a longer ferment to a certain point. If its really over-fermented though, then not only will the count decrease, the diversity will as well. I believe the diversity is even more important than the total count. My advise is to drink when it tastes best. At that point, it likely has the most balanced diversity. Going further may increase the count, but the dominate strains start to take over and those important minor strains get slowly cut down.
April 30, 2020
Caroline Showell-Rogers
Will the probiotic count increase with length of fermentation? I use a lot of grain and like to leave it until the milk really thickens. Will that increase the count?
April 30, 2020
Yemoos Nourishing Cultures
Hi Jim,
Thanks for pointing that out. That study showed about 1 billion cfu/g each. There were other strains, but they were very insignificant in count. I edited the article to reflect the change.
March 22, 2020
James Matthews
Hi Nathan. A really informative article. Thank you for that.
Please don’t think of this as criticism, because that is not intended. It is more likely a misunderstanding on my part, but I am a little bit confused with your comments on the study coming out of Scotland and Poland. You say “They found about 1 billion CFU per gram for Lactococcus and Lactobacillus.”. Is that 1 billion for each of Lactococcus and Lactobacillus, or 1 billion CFU for both together? And what about the number of CFU for all of the other strains that are found in Kefir?
If my suspicions are correct, then the total number of CFUs, for all strains, will be much more than the 1 billion CFU per gram that is claimed.
Best regards,
Jim
March 21, 2020
Yemoos Nourishing Cultures
Hi Bill – The CFU is only one part of what constitutes a healthy drink. Using raw grass-fed milk is incredibly healthy, but it may not increase the number of probiotics. What you will likely find is a more diverse healthy balance of strains and probiotics which is even more important. The grass-fed raw milk has many other benefits as well such as omega-3’s, enzymes, better nutritional profile, etc. And it also tastes much better.
October 16, 2019
William Heinicke
Hi Nathan – thanks for this article
I get Raw milk Kefir from a farm where the cows only eat grass and organic hay.
Any Idea how many billion CFU’s per cups I might be getting? thx
Bill
October 16, 2019
Marisa
Many thanks for posting this information. It was just what I was looking for. :-)
April 17, 2019
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