Kefir is a probiotic drink produced by adding kefir grains to milk and allowing it to ferment. Kefir grains are a mixture of bacteria, yeast, and polysaccharides. It is popular in many parts of the Middle East. It is believed that the word "kefir" means "feel good" in Turkish, or that it derives from kopur, meaning "milk," "froth," or "foam." Kefir typically has a tart and refreshing flavor, is slightly carbonated because of the naturally occurring carbon dioxide, and is somewhat thicker than milk. The flavor is described as sour, rich, and creamy. Natural kefir is not sweet, although it may be flavored with fruit.
Kefir is believed to be more nutritious and therapeutic than yogurt, supplying complete protein, essential minerals, and valuable B vitamins. The belief is that probiotic bacteria in kefir partially digest many milk proteins, making it more easily utilized by the body than other dairy products. At this time, high-quality human trials supporting the use of kefir for any indication are lacking. Better-designed clinical trials are needed before conclusions may be made regarding taking this product for any health condition.

Related Terms

Bioactive peptides, biofir (Hungarian), búlgaros (Spanish), calcium, Candida kefir, Enterococcus faecalis, Enterococcus faecium, fatty acids, fermented dairy product, fermented milk, folate, galactose, glucose, keefir, kefir cheese, kefir grains, kefir yogurt, kefīrs, kefyr, kephir, kewra, Kluyveromyces marxianus, kombucha, lactase, Lactobacillus, Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus bulgaricus, Lactobacillusdelbrueckii, Lactobacillus helveticus, Lactobacillus kefir, Lactobacilluskefiranofaciens, Lactococcus lactis, lactose, Leuconostoc, milkkefir, minerals, mudu kekiya, oligosaccharides, organic acids, probiotic, Saccharomyces cerevisiae, sphingomyelin, Streptococcus thermophilus, talai, whey protein, yeasts.
Combination products: Acipol® (Lactobacillus acidophilus and kefir grains).
Note: This monograph includes data specifically on the fermented milk drink kefir. Information on other forms of fermented milk is not included in this monograph.

evidence table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
High cholesterol (Grade: C)
Preliminary evidence suggests that kefir may be beneficial to patients with high cholesterol levels. Further studies are needed before conclusions can be drawn.
Lactose intolerance (Grade: C)
Limited evidence suggests that kefir may be beneficial to patients with lactose intolerance. Further studies are needed before conclusions can be drawn.
Reduction of chemotherapy side effects (Grade: C)
Evidence supporting the use of kefir to reduce chemotherapy side effects is currently lacking. Further studies are needed before conclusions can be drawn.