Fermented Dairy Product, Fermented Milk, Fromage Kéfir, Kéfir, Kefir Cheese, Kefir Grains, Kefir Yogurt, Kellermilch, Kjaklder Mjoklk, Lait Fermenté, Omaere, Produit Laitier Fermenté, Rob, Roba, Tarag.


Overview Information

Kefir is a probiotic drink made by fermenting milk.

Kefir is used for obesity, athletic performance, osteoporosis, high cholesterol, and many other conditions, but there is no good scientific evidence to support these uses.

How does it work?

Kefir contains actively growing bacteria and yeast. Their effect on milk results in production of enzymes and chemicals that affect the way food is digested.


Uses & Effectiveness?

Insufficient Evidence for

  • Diarrhea in people taking antibiotics (antibiotic-associated diarrhea). Some research shows that a kefir-containing drink does not reduce diarrhea caused by antibiotics in children.
  • Athletic performance. Early research shows that taking kefir after exercise does not improve running speed.
  • Nausea and vomiting caused by cancer drug treatment. Early research shows that taking kefir during chemotherapy treatment does not reduce stomach and intestinal problems. In fact, it might make these problems slightly worse.
  • Constipation. Early research shows that taking kefir helps increase the number of bowel movements in people with constipation. It also seems to soften stools.
  • A type of inflammatory bowel disease (Crohn disease). Early research shows that taking kefir might help with some symptoms of Crohn disease.
  • A digestive tract infection that can lead to ulcers (Helicobacter pylori or H. pylori). Early research shows that taking kefir along with standard treatment for H. pylori helps get rid of infections in more people than standard treatment alone.
  • High cholesterol. Early research shows that taking kefir does not lower cholesterol levels.
  • Symptoms of menopause. Early research shows that taking kefir might help with some symptoms of menopause, especially sleep.
  • A grouping of symptoms that increase the risk of diabetes, heart disease, and stroke (metabolic syndrome). Early research shows that taking kefir does not reduce blood pressure, cholesterol levels, or blood sugar in people with metabolic syndrome.
  • Obesity. Early research shows that eating kefir as part of a weight maintenance diet reduces body weight by a small amount in overweight or obese women. But eating low-fat milk dairy products instead of kefir seems to work just as well.
  • Swelling (inflammation) and sores inside the mouth (oral mucositis). Early research shows that rinsing the mouth with kefir and swallowing 250 mL of kefir twice daily for the first 5 days of chemotherapy does not prevent the development of sores inside the mouth caused by chemotherapy.
  • Weak and brittle bones (osteoporosis). Early research shows that taking kefir with calcium does not improve bone strength any more than calcium alone in adults with osteoporosis.
  • A type of inflammatory bowel disease (ulcerative colitis). Early research shows that taking kefir does not improve symptoms of ulcerative colitis.
  • Lactose intolerance.
  • Improving digestion.
  • Other conditions.
More evidence is needed to rate the effectiveness of kefir for these uses.

Side Effects

Side Effects & Safety

When taken by mouth: Kefir is POSSIBLY SAFE for most adults when taken for up to 12 weeks. Kefir can cause side effects like bloating, nausea, intestinal cramping, and constipation, especially when first started. These side effects usually stop with continued use.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn't enough reliable information to know if kefir is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Children: Kefir is POSSIBLY SAFE for children between the ages of 1 and 5 years when taken by mouth for up to 10 days.

AIDS and other conditions that weaken the immune system: Kefir contains actively growing bacteria and yeast. There is some concern that people with a weakened immune system might be more likely to develop infections from these bacteria or yeast.

Colon cancer: In people undergoing chemotherapy for colon cancer, kefir might increase side effects such as stomach and intestinal problems, mouth sores, drowsiness, sweats, and hair loss.



Moderate Interaction

Be cautious with this combination

  • Medications that decrease the immune system (Immunosuppressants) interacts with KEFIR

    Kefir contains live bacteria and yeast. The immune system usually controls bacteria and yeast in the body to prevent infections. Medications that decrease the immune system can increase your chances of getting sick from bacteria and yeast. Taking kefir along with medications that decrease the immune system might increase the chances of getting sick.
    Some medications that decrease the immune system include azathioprine (Imuran), basiliximab (Simulect), cyclosporine (Neoral, Sandimmune), daclizumab (Zenapax), muromonab-CD3 (OKT3, Orthoclone OKT3), mycophenolate (CellCept), tacrolimus (FK506, Prograf), sirolimus (Rapamune), prednisone (Deltasone, Orasone), corticosteroids (glucocorticoids), and others.



The appropriate dose of kefir depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for kefir. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

View References


  • Athanasiadis, I., Boskou, D., Kanellaki, M., and Koutinas, A. A. Low-temperature alcoholic fermentation by delignified cellulosic material supported cells of kefir yeast. J.Agric.Food Chem. 1999;47(10):4474-4477. View abstract.
  • Figler, M., Mozsik, G., Schaffer, B., Gasztonyi, B., Acs, P., Szili, B., Rab, R., and Szakaly, S. Effect of special Hungarian probiotic kefir on faecal microflora. World J Gastroenterol. 2-21-2006;12(7):1129-1132. View abstract.
  • Hertzler, S. R. and Clancy, S. M. Kefir improves lactose digestion and tolerance in adults with lactose maldigestion. J.Am.Diet.Assoc. 2003;103(5):582-587. View abstract.
  • Rabl, W., Liniger, B., Sutter, K., and Sigrist, T. [Ethanol content of Kefir water]. Blutalkohol 1994;31(2):76-79. View abstract.
  • Topuz, E., Derin, D., Can, G., Kurklu, E., Cinar, S., Aykan, F., Cevikbas, A., Disci, R., Durna, Z., Sakar, B., Saglam, S., Tanyeri, H., Deniz, G., Gurer, U., Tas, F., Guney, N., and Aydiner, A. 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.
  • Agerbaek M, Gerdes LU, Richelsen B. Hypocholesterolaemic effect of a new fermented milk product in healthy middle-aged men. Eur J Clin Nutr 1995;49:346-52. View abstract.
  • Alm L. Effect of fermentation on lactose, glucose, and galactose content in milk and suitability of fermented milk products for lactose intolerant individuals. J Dairy Sci 1982;65:346-52. View abstract.
  • Bekar O, Yilmaz Y, Gulten M. Kefir improves the efficacy and tolerability of triple therapy in eradicating Helicobacter pylori. J Med Food. 2011;14(4):344-7. View abstract.
  • Bellikci-Koyu E, Sarer-Yurekli BP, Akyon Y, et al. Effects of regular kefir consumption on gut microbiota in patients with metabolic syndrome: A parallel-group, randomized, controlled study. Nutrients. 2019;11(9). pii: E2089. View abstract.
  • Can G, Topuz E, Derin D, Durna Z, Aydiner A. Effect of kefir on the quality of life of patients being treated for colorectal cancer. Oncol Nurs Forum. 2009;36(6):E335-42. View abstract.
  • De Vrese M, Keller B, Barth CA. Enhancement of intestinal hydrolysis of lactose by microbial beta-galactosidase (EC of kefir. Br J Nutr 1992;67:67-75. View abstract.
  • Fathi Y, Faghih S, Zibaeenezhad MJ, Tabatabaei SH. Kefir drink leads to a similar weight loss, compared with milk, in a dairy-rich non-energy-restricted diet in overweight or obese premenopausal women: a randomized controlled trial. Eur J Nutr. 2016;55(1):295-304. View abstract.
  • Marquina D, Santos A, Corpas I, et al. Dietary influence of kefir on microbial activities in the mouse bowel. Lett Appl Microbiol 2002;35:136-40. View abstract.
  • Merenstein DJ, Foster J, D'Amico F. A randomized clinical trial measuring the influence of kefir on antibiotic-associated diarrhea. Arch Pediatr Adolesc Med 2009;163:750-4. View abstract.
  • Murofushi M, Mizuguchi J, Aibara K, Matuhasi T. Immunopotentiative effect of polysaccharide from kefir grain, KGF-C, administered orally in mice. Immunopharmacology 1986;12:29-35. View abstract.
  • Murofushi M, Shiomi M, Aibara K. Effect of orally administered polysaccharide from kefir grain on delayed-type hypersensitivity and tumor growth in mice. Jpn J Med Sci Biol 1983;36:49-53. View abstract.
  • O'Brien KV, Stewart LK, Forney LA, Aryana KJ, Prinyawiwatkul W, Boeneke CA. The effects of postexercise consumption of a kefir beverage on performance and recovery during intensive endurance training. J Dairy Sci. 2015;98(11):7446-9. View abstract.
  • Özcan H, Oskay Ü, Bodur AF. Effects of kefir on quality of life and sleep disturbances in postmenopausal women. Holist Nurs Pract. 2019;33(4):207-213. View abstract.
  • Richelsen B, Kristensen K, Pedersen SB. Long-term (6 months) effect of a new fermented milk product on the level of plasma lipoproteins--a placebo-controlled and double blind study (abstract). Eur J Clin Nutr 1996;50:811-5. View abstract.
  • Rimada PS, Abraham AG. Polysaccharide production by kefir grains during whey fermentation. J Dairy Res 2001;68:653-61. View abstract.
  • Schaafsma G, Meuling WJ, van Dokkum W, Bouley C. Effects of a milk product, fermented by Lactobacillus acidophilus and with fructo-oligosaccharides added, on blood lipids in male volunteers. Eur J Clin Nutr 1998;52:436-40. View abstract.
  • Schaafsma G, Meuling WJ, van Dokkum W, Bouley C. Effects of a milk product, fermented by Lactobacillus acidophilus and with fructo-oligosaccharides added, on blood lipids in male volunteers. Eur J Clin Nutr 1998;52:436-40. View abstract.
  • Shiomi M, Sasaki K, Murofushi M, Aibara K. Antitumor activity in mice of orally administered polysaccharide from Kefir grain. Jpn J Med Sci Biol 1982;35:75-80. View abstract.
  • Silva-Cutini MA, Almeida SA, Nascimento AM, et al. Long-term treatment with kefir probiotics ameliorates cardiac function in spontaneously hypertensive rats. J Nutr Biochem. 2019;66:79-85. View abstract.
  • Simova E, Beshkova D, Angelov A, et al. Lactic acid bacteria and yeasts in kefir grains and kefir made from them. J Ind Microbiol Biotechnol 2002;28:1-6. View abstract.
  • 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. View abstract.
  • Thoreux K, Schmucker DL. Kefir milk enhances intestinal immunity in young but not old rats. J Nutr 2001;131:807-12. View abstract.
  • Tu MY, Chen HL, Tung YT, Kao CC, Hu FC, Chen CM. Short-term effects of kefir-fermented milk consumption on bone mineral density and bone metabolism in a randomized clinical trial of osteoporotic patients. PLoS One. 2015;10(12):e0144231. View abstract.
  • Turan I, Dedeli Ö, Bor S, Ilter T. Effects of a kefir supplement on symptoms, colonic transit, and bowel satisfaction score in patients with chronic constipation: a pilot study. Turk J Gastroenterol. 2014;25(6):650-6. View abstract.
  • Wang MC, Zaydi AI, Lin WH, Lin JS, Liong MT, Wu JJ. Putative probiotic strains isolated from kefir improve gastrointestinal health parameters in adults: a randomized, single-blind, placebo-controlled study. Probiotics Antimicrob Proteins. 2019. View abstract.
  • Yilmaz I, Dolar ME, Özpinar H. Effect of administering kefir on the changes in fecal microbiota and symptoms of inflammatory bowel disease: A randomized controlled trial. Turk J Gastroenterol. 2019;30(3):242-253. View abstract.

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