January 09, 2019

How many probiotics (or CFU) does kefir really have?

CFU probiotics of milk kefir

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.


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.  


[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