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.

Background

• 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.

Scientific Evidence

Tradition/Theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

• Allergy, antioxidant, athletic performance enhancement, attention-deficit hyperactivity disorder (ADHD), biliary/gall bladder disease (cholecystitis, cholelithiasis, colic), bone density, cancer, Crohn's disease, depression, diabetes, diarrhea, gastrointestinal disorders, high blood pressure, immune stimulant, inflammation, ischemic heart disease, metabolic disorders, nutritional support (probiotic), pain, pancreatic disorders, tuberculosis, sleep disorders.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

• For high cholesterol, 500 milliliters of kefir has been taken by mouth daily for four weeks.

• For lactose intolerance, one treatment with 508 grams of plain kefir or 519 grams of raspberry-flavored kefir has been taken by mouth following an overnight fast.

• For reduction of chemotherapy side effects, on the first five days of each chemotherapy cycle, an oral lavage (mouth wash) with kefir was carried out and then 250 milliliters of kefir was taken by mouth.

Children (under 18 years old)

• There is no proven safe or effective dose for kefir in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

• Avoid with known allergy or hypersensitivity to dairy products.

Side Effects and Warnings

• Kefir may cause gastrointestinal side effects such as bloating, constipation, diarrhea, increased stool frequency, loose stools, and stomach cramping.

• Use cautiously in people who are lactose intolerant, although there is evidence that kefir is better tolerated than other dairy products.

• Use medicinal levels cautiously when pregnant or breastfeeding, due to a lack of safety or evidence in this area.

• Use cautiously in alcoholics, as kefir may contain up to 16 grams of ethanol per liter on the second day of the fermentation process and up to 38 grams of ethanol per liter after 7-10 days.

• Use cautiously in high doses in children, as kefir may contain up to 16 grams of ethanol per liter on the second day of the fermentation process and up to 38 grams of ethanol per liter after 7-10 days.

• Avoid with known allergy or hypersensitivity to dairy products.

Pregnancy and Breastfeeding

• In nonallergic women, kefir is likely safe when consumed in amounts generally found in foods. There is a lack of scientific data about the safety of medicinal use of kefir during pregnancy or breastfeeding. Historically, kefir provided supplemental nourishment for pregnant and nursing women and increased breast milk production. In Russia, kefir is widely used as a first food for infants in addition to breast milk.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

• Kefir may interact with alcohol, antibiotics, antifungals, disulfiram (Antabuse®), and metronidazole (Flagyl®).

Interactions with Herbs and Dietary Supplements

• Kefir may interact with antibacterials, antifungals, B vitamins, calcium, Coprinopsis atramentaria (a mushroom), and probiotics.

Author Information

• This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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2. Can G, Topuz E, Derin D, et al. Effect of kefir on the quality of life of patients being treated for colorectal cancer. Oncol Nurs Forum 2009 Nov;36(6):E335-42. View Abstract

3. Ebringer L, Ferencik M, Krajcovic J. Beneficial health effects of milk and fermented dairy products--review. Folia Microbiol (Praha) 2008;53(5):378-394. View Abstract

4. Figler M, Mozsik G, Schaffer B, et al. Effect of special Hungarian probiotic kefir on faecal microflora. World J Gastroenterol 2006;12(7):1129-1132. View Abstract

5. Forssen KM, Jagerstad MI, Wigertz K, et al. Folates and dairy products: a critical update. J Am Coll Nutr 2000;19(2 Suppl):100S-110S. View Abstract

6. Gulmez M, Guven A. Survival of Escherichia coli O157:H7, Listeria monocytogenes 4b and Yersinia enterocolitica O3 in different yogurt and kefir combinations as prefermentation contaminant. J Appl Microbiol 2003;95(3):631-636. View Abstract

7. Hertzler SR, Clancy SM. Kefir improves lactose digestion and tolerance in adults with lactose maldigestion. J Am Diet Assoc 2003;103(5):582-587. View Abstract

8. Narva M, Nevala R, Poussa T, et al. The effect of Lactobacillus helveticus fermented milk on acute changes in calcium metabolism in postmenopausal women. Eur J Nutr 2004;43(2):61-68. View Abstract

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10. Oleinichenko EV, Mitrokhin SD, Nonikov VE, et al. [Effectiveness of acipole in prevention of enteric dysbacteriosis due to antibacterial therapy]. Antibiot Khimioter 1999;44(1):23-25. View Abstract

11. Ostman EM, Liljeberg Elmstahl HG, Bjorck IM. Inconsistency between glycemic and insulinemic responses to regular and fermented milk products. Am J Clin Nutr 2001;74(1):96-100. View Abstract

12. Santos A, San Mauro M, Sanchez A, et al. The antimicrobial properties of different strains of Lactobacillus spp. isolated from kefir. Syst Appl Microbiol 2003;26(3):434-437. View Abstract

13. St Onge MP, Farnworth ER, Savard T, et al. Kefir consumption does not alter plasma lipid levels or cholesterol fractional synthesis rates relative to milk in hyperlipidemic men: a randomized controlled trial [ISRCTN10820810]. BMC Complement Altern Med 2002;2(1):1. View Abstract

14. Studd C. Probiotic containing fermented milk supplement may improve the institution of early enteral nutrition. Crit Care Med 2000;28(4):1255-1256. View Abstract

15. Topuz E, Derin D, Can G, et al. Effect of oral administration of kefir on serum proinflammatory cytokines on 5-FU induced oral mucositis in patients with colorectal cancer. Invest New Drugs 2008;26(6):567-572. View Abstract