A centuries-old fermented milk drink with origins in the Caucasus mountains is gaining attention for its potential health benefits. Kefir, produced using unique granules containing a complex community of bacteria and yeasts, is now the subject of increasing scientific study [[1]]. Researchers are investigating its role in everything from digestive health and immune function to restoring balance within the gut microbiome, a key area of focus in modern health and nutrition.
A traditional fermented beverage originating in the Caucasus mountains is increasingly attracting scientific scrutiny. Research published in databases like PubMed and BMC describes it as a living symbiotic matrix, comprised of a diverse community of 30 to 60 microorganisms interacting with various bodily functions. While human studies remain limited and varied, initial findings suggest a potential role in digestive regulation, immune modulation, and restoring microbial balance.
Kefir is produced from white, gelatinous granules that concentrate a community of lactic bacteria and yeasts. During the fermentation of sugars, these granules produce compounds like lactic acid, carbon dioxide, ethanol, and other active metabolites that modify the structure of the original liquid, creating a beverage rich in live microorganisms.
“It’s a natural symbiosis between yeasts and bacteria that is enhanced in that shared environment,” explains César Casavola, president of the Argentine Society of Nutritionists (SAMENUT).
Its origins trace back to traditional practices in the Caucasus region, where milk was fermented in unwashed goatskin containers. This process led to the discovery of a new, acidic beverage with a unique flavor and extended shelf life, created by a white film. They called it kefir, derived from the Turkish word keyif, which refers to a feeling of well-being.
Two Main Varieties
Most studies conducted to date are in vitro or on animal models, but suggest that regular kefir consumption is associated with improvements in several key indicators.
1. Promotes Microbial Diversity
Bacteria such as Lactobacillus kefiranofaciens, L. plantarum, L. acidophilus, and yeasts like Saccharomyces cerevisiae or Kluyveromyces marxianus help generate organic acids, enzymes, and kefiran, a key polysaccharide. These elements modify the intestinal environment, reducing pH, displacing opportunistic bacteria, and acting as a prebiotic substrate. The growing interest in gut health is driving demand for products like kefir, potentially impacting the functional food market.
Both milk and water-based varieties can increase bacterial diversity, which is particularly beneficial after antibiotic treatments or periods of stress.
“It promotes the development of Lactobacillus and Bifidobacterium while suppressing harmful microorganisms, which contributes to restoring a healthy intestinal environment,” Casavola notes.
Additionally, a balanced microbiota improves the absorption of nutrients like calcium and magnesium. “This enhances the bioavailability of essential vitamins and minerals,” adds nutritionist Milagros Sympson (M.N. 12067).
A study in BMC Medicine showed that in critically ill patients, kefir helped decrease intestinal dysbiosis, a common imbalance in compromised health contexts.
2. Alleviates Digestive Symptoms
Kefir improves digestion by normalizing intestinal transit and may be helpful in cases of constipation, diarrhea, or irritable bowel syndrome. “Its probiotic capacity and the reduction of colonic pH favor these effects,” Casavola states.
It also produces enzymes that break down lactose, facilitating digestion for those with intolerance. The peptides and acids it generates act locally to reduce inflammation: “This strengthens the intestinal barrier, preventing the entry of toxins or pathogens,” Sympson explains.
3. Boosts Defenses
“Its immunomodulatory effects come from both the bacteria and the compounds synthesized during fermentation,” Casavola comments. These include peptides that activate specific immune responses against infections.
Sympson emphasizes that a key part of the immune system resides in the gut, so maintaining its balance promotes a better overall response.
How to Prepare It
Kefir can be made at home by placing the granules in a jar with milk (animal or vegetable) or water with sugar. Fermentation takes between 24 and 48 hours at room temperature. Then it is strained, the granules are reused, and it is stored refrigerated. Casavola recommends:
Regarding quantity, 100 to 200 ml daily is sufficient to obtain proven benefits. “The most important thing is consistency, that the kefir is of good quality and is accompanied by a balanced diet,” Sympson concludes.
