If you've ever held a handful of milk kefir grains — really looked at them, felt their soft, cauliflower-like weight in your palm — you would certainly have wondered where on earth they came from. How does something like this exist? How did anyone first think to put this particular living community of bacteria and yeast into a bag of milk and let something extraordinary happen?
The answer, it turns out, is part legend, part espionage, and pretty bloody amazing actually.
Born in the Mountains
The true origin of milk kefir grains is lost to time, shrouded in legend and mystery. One piece of the puzzle is quite clear - we do know is that they originated centuries ago among the nomadic tribes living on the northern slopes of the Caucasus Mountains — the dramatic region that divides Europe and Asia. It was there, in North Ossetia, that the Ossetians — descended from the nomadic Scythians who settled in the area — first harnessed kefir grains to ferment milk in simple leather bags. How exactly they first came upon the grains, no one can say for certain. There are no written records of those earliest moments, only stories passed down through generations, carrying with them no doubt a good helping of embellishment along the way.
But the grains themselves are ancient beyond easy imagining. Kefir has been found in graves in the Bronze Age Xiaohe Cemetery in what is now China's Xinjiang province, dating back 3,600 years. More on that in a moment.
The Grains of the Prophet
In the Caucasus region, kefir grains became known as the "Grains of the Prophet." The traditional legend holds that the prophet Mohammed gifted kefir grains to the Orthodox Christians in the region, teaching the people how to make kefir. They revered it as a health-promoting food, and owning kefir grains was equated with wealth.
The tribes believed the grains would lose their magical powers if their existence were revealed to outsiders. To talk about them, or worse, to give them away, was to commit a religious crime and to risk destroying an ancient tradition. The kefir grains and methods for making kefir were kept secret for many generations. For centuries, the rest of the world had barely any idea this living treasure existed.
The Daily Ritual
I love this detail perhaps more than any other: the Ossetians added kefir grains to goatskin bags, poured in fresh milk, and left the mixture in the sun to ferment. Any guests or family members coming and going from the house were expected to mix the kefir by giving the bag a gentle kick or prod as they passed. As kefir was removed, more fresh milk was added, making the fermentation process continuous. Generation after generation, the grains were fed, tended, and passed on. They were family. They were wealth. They were, in a very real sense, sacred.
The word kefir is believed to come from the Turkish keyif, meaning "a good feeling" — a nod to both its taste and its long-standing reputation for wellness. And this makes sense because milk kefir contains Tryptophan which ignites seratonin - which makes you feel good!
The Steppe Cultures & Fermented Milk
The Caucasian tradition of the goatskin bag hung at the doorway was not unique. Across the vast steppes of Central Asia — from the Caucasus all the way to Mongolia — nomadic cultures were doing something similar, with their own fermented milk traditions, their own leather vessels, and their own understanding that movement was part of the process.
In Mongolia, the milk is filtered through a cloth and poured into a large open leather sack called a khukhuur, which is usually suspended next to the entrance of the yurt. The stirring needs to be repeated regularly over one or two days — and traditionally, anyone entering or leaving the yurt would do a few strokes.
Suspended from the roof of the ger next to the entrance, it is considered polite for all who visit to add several mixes. On average, the liquid will be churned up to 4,000 times before drinking — the more times it is churned, the better the batch will taste.
The resulting drink is airag — fermented mare's milk, known more widely as kumis — a fermentation process caused by a combination of lactic acid bacteria and yeast, similar to kefir, with the stirring ensuring that all parts of the milk are fermented equally.
And here is the detail I love most: back in the days before the yurt entrance tradition, airag was made in leather bags hung on the horse's back. Due to the heat produced by the horse's body as it moved around, the milk in the leather pouch was soon fermented. Due to the same movement, the content was constantly mixed. The same leather pouch was used for making batch after batch of airag, without washing it, as it played the role of a starter culture — the bacteria remaining on the walls of the bag inoculating each new batch.
The horse itself was the fermenting vessel, the heat source, and the mixing tool — all at once. It is hard to imagine a more elegant integration of fermentation into daily nomadic life.
For roaming warriors such as Genghis Khan and Attila the Hun, mares provided kumis, meat, and transportation all in one. People transported the liquid in leather bags, often hanging them where passersby could easily punch the sack to keep the kumis agitated.
The traditional technique of producing airag in a khokhuur vessel in Mongolia was inscribed in December 2019 on the UNESCO Representative List of the Intangible Cultural Heritage of Humanity. It is considered not just a food tradition but a living cultural practice — one that connects the Mongolian people to their nomadic past and to each other.
What strikes me about all of this — the Caucasian goatskin bags at the doorway, the Mongolian khukhuur stirred by every passing hand, the leather pouches on horseback — is how consistent the underlying wisdom is across vast distances and very different cultures. Movement matters. Community matters. The vessel carries the culture forward. And the door of the home is where the ferment lives — touched by everyone who passes through it, fed by the daily life of the household.
The Chinese Connection!
For a long time, the story of kefir began and ended in the Caucasus. But in 2024, remarkable archaeological research shifted that understanding considerably.
In 2003, archaeologists had discovered white substances on the heads and necks of mummies unearthed at the Xiaohe cemetery in China's Tarim Basin, dating from the Bronze Age — approximately 3,600 years ago. For years scientists could only speculate on what these mysterious substances were. Then researchers recovered DNA from the ancient samples and confirmed that the white substances were kefir cheese, produced by the Bronze Age Xiaohe population. They identified bacterial and fungal species including Lactobacillus kefiranofaciens and Pichia kudriavzevii — both commonly found in present-day kefir grains.
The Xiaohe tombs were remarkably well preserved — sealed from air, moisture and sand, with the dry cold climate contributing to their preserved state. That the kefir cheese was found around the necks of the mummies tells us just how prized it was. And crucially: although it was previously assumed that kefir spread from the Northern Caucasus outward, the researchers found an additional spreading route from Xinjiang to inland East Asia — and the bacterial strains showed a closer connection to Tibetan strains than to Caucasian ones.
In other words: kefir didn't just originate in the Caucasus and travel west. There was an entirely separate, ancient kefir tradition flourishing in what is now China, at least 3,600 years ago. The Caucasus story is real — but it is not the whole story.
Further afield
Strange tales spread of this unusual Caucasian beverage with its supposed magical properties. Even Marco Polo mentioned kefir in the chronicles of his travels in the East. But for centuries it remained largely unknown outside the mountains where we think it was born.
That began to change in the 19th century. The Russian immunologist Dr. Ilya Ilyich Metchnikoff — who received the Nobel Prize for his work on immunity in 1908 — became interested in the exceptional longevity of the people in the Caucasus region. He came to the conclusion that soured milk, including milk kefir, was one of the keys to longevity and well-being. Russian doctors believed that kefir was beneficial for health, and the first scientific studies were published at the end of the nineteenth century. The All Russian Physicians' Society was determined to obtain kefir grains and make kefir available to their patients. Unfortunately, the grains required to produce it were extremely difficult to obtain — and the people of the Caucasus had no intention of giving them up.
The Heist (Sort Of)
Ok I always feel like I am making this part up - but here it is:
The Blandov brothers, who owned the Moscow Dairy with operations in the Caucasus, devised a plan. They sent a beautiful young employee named Irina Sakharova to the court of a local prince, Bek-Mirza Barchorov, instructed to charm him into handing over some of his precious grains. The prince was quite taken with Irina — but had no intention of parting with the Grains of the Prophet. So instead, he kidnapped her, invoking the local custom of stealing a bride. (I like to imagine that was preplanned and performative rather than an actual kidnapping.....)
Irina was rescued by agents of the Blandov brothers and brought before the Tsar to seek justice. The Tsar ruled that the prince was to give Irina ten pounds of kefir grains as compensation for the insults she had endured. The precious grains were taken back to the Moscow Dairy, and the first bottles of kefir ever manufactured commercially were offered for sale in Moscow in September 1908.
One woman with ten pounds of grains and so - an entire large scale industrial kefir was born.
Good news? It went straight into the hospitals
The Blandov brothers didn't waste a moment. The grains had been obtained specifically for the physicians' society, and that's exactly where the kefir went. Kefir was used in Russian hospitals to treat a wide variety of conditions including digestive disorders, cancer, atherosclerosis, and tuberculosis. Russian doctors had long suspected this mountain drink held something remarkable — now they had the supply to prove it.
By the 1930s, kefir was being produced on a large commercial scale to meet widespread public demand across Russia. It had moved from mountain secret to hospital medicine to everyday staple in the space of a generation.
And in 1973 — perhaps the most quietly moving footnote in this whole story — the Minister of the Food Industry of the Soviet Union wrote a letter to Irina Sakharova, then 85 years old, thanking her for bringing kefir to the Russian people. She had been 20 years old when she boarded that train to the Caucasus. She lived to see what it became.
The story of kefir in Russia — how it went from hospital wards to Soviet canteens to school lunches and became one of the most consumed drinks in the country — deserves its own post. That one is coming soon.
BUT ...how are kefir grains made?
As with much of our natural world ... they form through a process that is still not entirely understood, which is part of what makes them so beautiful. We cannot replicate them. Only imitate them.
Scientists have proposed that kefir grain formation begins when Lactobacillus kefiranofaciens and Saccharomyces turicensis start to auto-aggregate and co-aggregate into small granules. As the pH drops during fermentation, that aggregation intensifies. Other bacteria and yeasts — including Lactobacillus kefiri, Kluyveromyces marxianus, and Pichia fermentans — then adhere to the surface, building thin biofilms. From there, more yeasts and lactobacilli continue to co-aggregate, eventually forming the three-dimensional structure we recognise as a kefir grain.
In other words: a kefir grain is not a single organism. It is an entire community — a symbiotic city of microorganisms —(SCOBY) that built itself, layer by layer, through relationships between bacteria and yeast over time. Up to 50 different bacterial and yeast species have been found in grain-based milk kefir. That's an ecosystem!
Our gorgeous kefir grains are, as you likely suspected while holding them in your hands - a biological mystery. They cannot be created in a lab — and must be passed down.
Can Scientists Replicate Them?
The problem is not identifying what's in a kefir grain — scientists can do that. Labs have developed powdered culture starters that mimic kefir to produce a commercially consistent product. However, these imitations contain far fewer probiotics and cannot replicate the grain structure itself, or its full microbial complexity.
At industrial scale, kefir grains are rarely used due to their slow growth, complex application, poor reproducibility and high costs. Instead, mixtures of defined lactic acid bacteria and sometimes yeasts are applied — which alter the sensory and functional properties compared to natural grain-based milk kefir.
What does that mean in practice? Traditional kefir made with kefir grains contains up to 60–70 different microorganisms in complex symbiotic relationships. Store-bought kefir typically uses only 7–9 defined starter cultures — often a selection of strains such as Lactococcus lactis, Leuconostoc mesenteroides, Streptococcus thermophilus, Lactobacillus acidophilus, and sometimes Saccharomyces cerevisiae as the token yeast. Laboratory tests show most commercial kefir contains no yeasts at all — which technically makes them acidified milk products rather than true kefir.
Consistency, shelf stability, predictability — these are the priorities of industrial production, and there's nothing wrong with that. But it is a fundamentally different thing to what you make at home with living grains.
The fizz alone gives it away. Kefir's slightly effervescent nature comes directly from yeasts in the culture breaking down lactose into carbon dioxide — and only grain-made kefir reliably delivers that traditional natural fizz. When your home kefir bubbles, that's not an accident - that's the yeasts doing what they've always done. How happy is that? I love the effervecence of milk kefir. I find fizzy milk very charming indeed - even though the words fizzy milk ... unless you know how good it is - sounds kind of wrong.
On Immortality
Now for the detail I find most extraordinary of all — and which I think about more than is probably reasonable.
Unlike so many other organisms, kefir does not have programmed cell death — meaning it is one of the immortals, and will keep going forever if properly fed. The organisms that make up kefir grains don't carry within them the biological instruction to die. There is no senescence, no expiry date, no winding down built into them. Fed regularly, they simply continue — growing, dividing, fermenting, passing themselves forward through time.
Most living things age. Cells replicate imperfectly, slow down, and eventually stop. That process — programmed cell death — is woven into the fabric of life as we generally understand it. Kefir grains don't work that way. They are, in a very real biological sense, immortal.
Which means the grains sitting on your bench right now are not the descendants of ancient grains. They are, in a meaningful biological sense, the same living community of organisms that has been fermenting milk since the mountains of the Caucasus. Every grain ever used is part of one continuous, unbroken living thread stretching back thousands of years.
And that gorgeous reader - is what these grains actually are.
Please love them. x
The story of kefir in Russia — Soviet hospitals, canteens, school lunches, and why it became one of the most consumed drinks in the country — is coming soon.
Want to know more about caring for your milk kefir grains? [Visit our FAQ] or [shop our milk kefir grains]. I have also written about kefir, its culture, and how to make it at home in both [Ferment for Good] and [Wild Drinks], available in the shop.
Sources for this post include: Raw Milk Institute, Yemoos Nourishing Cultures, Revolution Fermentation, Cultured Food Life, Russiapedia, Wikipedia (Kefir), Sci.News (Bronze Age Kefir Cheese research, 2024), PMC/NCBI (milk kefir microbiology), and Startercultures.eu.
