Kumis is a fermented drink made from mare’s milk, with a slightly sour taste and a mild fizz from natural carbonation. It contains between 0.6% and 2.5% alcohol, roughly on par with a light beer, and has been a dietary staple across Central Asia for centuries. The drink goes by many names: airag in Mongolia, kumys in Kazakhstan, and koumiss or kymyz in various other Turkic-speaking regions.
How Kumis Is Made
The basic process is straightforward: fresh mare’s milk is combined with a starter culture containing bacteria and yeasts, then left to ferment. What makes kumis unusual among dairy products is that two types of fermentation happen at the same time. Bacteria convert the milk’s natural sugar (lactose) into lactic acid, giving the drink its tang. Yeasts convert some of that sugar into ethanol and carbon dioxide, creating a gentle alcohol content and the characteristic effervescence.
Traditionally, the milk was stored and fermented in bags made from animal hide, often cowhide or horse skin. In Mongolia, the cowhide vessel is called a khokhuur, and the milk is stirred regularly with a wooden paddle called a buluur. UNESCO recognized this traditional Mongolian technique as part of the world’s intangible cultural heritage. The process relied on wild microbes from the environment and from previous batches, meaning each region’s kumis had a slightly different character depending on the local microbial ecosystem.
Modern industrial production uses pasteurized mare’s milk fermented at a controlled lower temperature (around 20°C, compared to the roughly 27°C of a traditional batch at room temperature). This produces a milder, more standardized product. Traditional fermentation breaks down about 62% of the milk’s lactose, while industrial methods only break down about 26%, resulting in a sweeter, less acidic drink with lower alcohol content. In Europe and North America, kumis is sometimes made with cow’s milk as a substitute, though the result differs noticeably in flavor and texture because mare’s milk has less fat and casein than cow’s milk.
What It Tastes Like
Kumis has a tart, slightly yeasty flavor with a thin, almost watery body compared to yogurt-based drinks. The carbonation gives it a light fizz on the tongue. Depending on how long it ferments, the sourness and alcohol strength vary. A standard batch sits around 2% alcohol, mild enough that it’s consumed casually throughout the day in pastoral communities. Stronger versions can be distilled into a more potent spirit.
Nutritional Profile
Mare’s milk starts with a different nutritional baseline than cow’s milk. It’s lower in fat (about 1.0% to 1.5%) and protein (about 2.1% to 2.7%) but significantly higher in lactose (6% to 7%, compared to roughly 4.7% in cow’s milk). The protein composition also differs: mare’s milk is richer in whey proteins like lactalbumin, with a nearly equal ratio of casein to whey. This makes it closer in structure to human breast milk than cow’s milk is.
After fermentation, kumis retains roughly 1.7% to 1.9% protein and 0.6% to 1.3% fat. It’s notably rich in vitamin C, which is unusual for a dairy product, along with vitamins A, E, B2, B12, and pantothenic acid. Mineral content includes meaningful amounts of phosphorus and calcium. The lactic acid content ranges from 0.7% to 1.8%, contributing both to its flavor and to its role as a carrier of live beneficial bacteria.
Kumis and Lactose Tolerance
Despite mare’s milk being higher in lactose than cow’s milk, the fermentation process breaks a substantial portion of that lactose down into lactic acid, ethanol, and carbon dioxide. This conversion, especially in traditionally fermented batches, makes kumis tolerable for many people with lactose intolerance. Clinical reports also indicate that mare’s milk is well tolerated by many children with cow’s milk protein allergy, since its protein structure is quite different from that of cow’s milk.
Probiotic and Health Properties
Kumis contains a diverse community of live bacteria and yeasts. The dominant bacterial species include several types of lactobacilli and lactococci, while the yeast population includes species that ferment either lactose or galactose to produce alcohol. This microbial diversity is similar to what you’d find in kefir, another dual-fermented dairy product, though kumis has its own distinct microbial fingerprint shaped by the mare’s milk environment.
Traditionally, kumis has been used across Central Asia as a remedy for digestive problems, anemia, and general weakness. Historical medical literature describes its use in treating tuberculosis patients at sanatoriums in Russia and Kazakhstan during the 19th and 20th centuries. Modern understanding attributes many of these effects to its probiotic content: the live bacteria support gut health, while the easily digestible proteins and vitamins provide nutrition in a form the body can absorb efficiently. Research in animal models has shown that fermented mare’s milk can have protective effects on the gastrointestinal tract, support immune function, and aid metabolism.
Cultural Role in Central Asia
Kumis is far more than a beverage in the nomadic and semi-nomadic cultures where it originated. Turkic peoples historically attached religious significance to it, and it remains deeply embedded in daily life across Kazakhstan, Kyrgyzstan, and Mongolia. In Mongolia, airag is served as a holy drink during festivals, offered to guests as a sign of hospitality, and used in ritual blessings. The traditional production season follows the mare’s lactation cycle, typically running from late spring through autumn, making kumis a seasonal marker of pastoral life.
In Kazakhstan, kumys is a point of national pride, with regional competitions and festivals dedicated to its production. Kyrgyz families often keep their own starter cultures, passed down through generations, each carrying a unique blend of microorganisms that gives their kumis a distinct flavor. The drink’s cultural weight is comparable to wine in Mediterranean cultures: it marks celebrations, seals social bonds, and carries symbolic meaning that goes well beyond its nutritional value.