Kefir: benefits, dosage, contraindications
Other name(s)
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Family or group:
Probiotics, Super Food
Active ingredients:
Lactic ferments
Lactobacilli
Indications
Rating methodology
EFSA approval.
Metabolic syndrome ✪✪✪✪✪
Kefir is recognized for its metabolic benefits, notably its ability to modulate inflammatory responses. A meta-analysis evaluated the effect of consuming fermented dairy products, including kefir, on various inflammatory biomarkers. It concluded an association between these products and reduced levels of C-reactive protein (CRP), a key marker of inflammation. This reduction suggests that kefir could help attenuate inflammation associated with conditions like cardiovascular diseases and metabolic syndrome. Moreover, a study on overweight or obese women demonstrated that adding two portions of kefir to a weight maintenance diet for eight weeks resulted in superior weight loss compared to the diet alone. Furthermore, a randomized controlled clinical trial explored the impact of kefir consumption on apolipoprotein A1 (ApoA1) levels in patients with metabolic syndrome. Sixty-two participants were allocated to receive either 180 mL of kefir or an equivalent volume of unfermented milk daily for 12 weeks. The results revealed a significant 3.4% increase in serum ApoA1 concentrations in the kefir group, while these levels decreased by 2.4% in the milk group. An increase in ApoA1 levels is often considered beneficial for cardiovascular health, as ApoA1 is the main component of high-density lipoproteins (HDL), often referred to as "good cholesterol."
Posologie
Oral intake
180 - 1200 mL
12 - weeks
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.
Effect of kefir beverage consumption on glycemic control: A systematic review and meta-analysis of randomized controlled clinical trials
Effects of Regular Kefir Consumption on Gut Microbiota in Patients with Metabolic Syndrome: A Parallel-Group, Randomized, Controlled Study
Effects of fermented dairy products on inflammatory biomarkers: A meta-analysis
Effects of Kefir Consumption on Cardiometabolic Risk Factors: A Systematic Review and Meta-analysis of Randomized Controlled Trials
Helicobacter pylori Infection ✪✪✪✪✪
A small clinical study conducted on patients with Helicobacter pylori infection shows that consuming 250 ml of kefir twice a day for two weeks increases the eradication rate of H. pylori by 56% compared to a placebo milk. All patients also received a triple therapy consisting of lansoprazole, amoxicillin, and clarithromycin.
Posologie
Oral route
500 mL
2 weeks
Chronic Inflammatory Bowel Diseases ✪✪✪✪✪
Kefir, a fermented dairy product, has been studied for its potential effects in managing chronic inflammatory bowel diseases, including Crohn's disease and ulcerative colitis. A small clinical study in adults with Crohn's disease revealed that consuming 200 mL of kefir twice a day for four weeks reduced bloating sensations and improved overall symptoms compared to the initial study conditions. However, these results should be interpreted with caution due to the lack of a control group.
Posologie
Oral route
400 mL
4 weeks
Digestive Disorders ✪✪✪✪✪
Kefir, known for its probiotic properties, shows promising therapeutic potential in treating dyspepsia. A study on adults with Crohn's disease showed that consuming 200 mL of kefir twice a day for four weeks significantly reduces bloating sensations and improves overall symptoms. Additionally, consuming kefir during pregnancy might reduce the risk of developing cow's milk protein allergy in children up to three years old. Further research, conducted by Steven R. Hertzler and Shannon M. Clancy, has shown that kefir improves lactose digestion and reduces intolerance symptoms such as flatulence, suggesting better lactase activity in kefir compared to milk. Another pilot study in Turkey observed an improvement in chronic constipation symptoms, with an increase in bowel movement frequency and acceleration of transit in patients with slow transit.
Posologie
Oral route
400 mL
Does maternal fermented dairy products consumption protect against cow's milk protein allergy in toddlers?
Effect of administering kefir on the changes in fecal microbiota and symptoms of inflammatory bowel disease: A randomized controlled trial
Putative Probiotic Strains Isolated from Kefir Improve Gastrointestinal Health Parameters in Adults: a Randomized, Single-Blind, Placebo-Controlled Study
Kefir improves lactose digestion and tolerance in adults with lactose maldigestion
Properties
Digestive effect
Naturally rich in probiotics, kefir is beneficial for digestive health, as demonstrated by a study in patients with inflammatory bowel disease. This research highlighted the positive influence of regular kefir consumption on the intestinal flora and the quality of life of patients suffering from ulcerative colitis and Crohn's disease. Kefir provides Lactobacillus, essential for a balanced gut microbiota. Furthermore, participants reported improvement in digestive symptoms such as bloating and an increase in the general feeling of well-being, indicating not only an improvement in digestive function but also a positive impact on psychological well-being. Additionally, kefir has shown the ability to accelerate colonic transit, particularly in patients with slow transit. These effects are likely due to the richness in microorganisms of kefir, which act favorably on intestinal motility and digestive function.
Usages associés
Immunomodulatory
The bioactive compounds in kefir play an important role in modulating the immune system. Exopolysaccharides (EPS) and particularly kefiran are active against various acute inflammations such as colitis, reducing inflammatory markers such as TNFα and IL-8. They work by modulating pro-inflammatory cytokines and inhibiting pathways like NF-κB, essential in inflammatory processes. Kefiran has shown significant effects in mouse models of colitis, reducing weight loss and colonic tissue damage. This effectiveness is comparable to that of common drug treatments like prednisolone. Moreover, kefir acts on the intestinal barrier by increasing the expression of occluding proteins like occludin and claudin-1, thus strengthening the integrity of the intestinal mucosa. Kefir has also demonstrated anticancer properties, notably against breast, colon, and liver cancers. Kefiran reduced cancer cell viability, with dose-dependent effects observed in various in vitro studies.
Usages associés
Antimicrobial
Thanks to its bioactive components, including exopolysaccharides (EPS) such as kefiran, and organic acids like lactic acid, kefir exerts notable antimicrobial activity. The EPS, mainly produced by Lactobacillus kefiranofaciens, play a crucial role in inhibiting various pathogenic bacterial strains by forming a physical barrier that prevents bacterial invasion and biofilm formation. Kefiran has notably shown effectiveness against bacteria such as Escherichia coli and Staphylococcus aureus, altering the permeability of their cell membranes, which disrupts their normal functioning. On the other hand, the organic acids produced by kefir, notably lactic acid, act by lowering the pH, which directly affects the survival of pathogenic bacteria. This acidifying effect inhibits the growth of pathogens such as Klebsiella pneumoniae and Bacillus cereus. The bioactive peptides resulting from milk proteolysis during kefir fermentation also display antimicrobial properties by directly attacking the cell membranes of pathogens. Produced by species such as Lactobacillus paracasei, these peptides can disrupt the lipid structures of bacterial membranes, leading to leakage of vital cell components and bacterial death.
Cardiovascular
The bioactive compounds in kefir play an essential role in modulating cardiovascular health by positively influencing glucose metabolism and lipid profiles. Research has shown that kefir might improve diabetes and obesity markers, although results are sometimes mixed. For example, in murine models of diabetes and obesity, kefir administration did not alter plasma glucose levels but significantly reduced adipose tissue weight and decreased the expression of pro-inflammatory genes and fatty acid synthesis in adipocytes. This suggests regulation of fatty acid metabolism in adipose tissue rather than a direct impact on plasma glucose levels. Furthermore, studies have shown that kefir, particularly the exopolysaccharides (EPS) produced by certain lactic strains, possesses potential hypocholesterolemic properties in vitro, although these effects have not been corroborated in vivo.
Usages associés
Bone Density
Kefir peptides have shown promising potential in the prevention of osteoporosis in an experiment with ovariectomized mice, simulating the decrease in estrogen levels as in postmenopausal women. These peptides significantly increase bone mineral density, as well as mechanical properties such as elasticity modulus and bone hardness. Compared to the standard treatment with calcium carbonate, kefir peptides demonstrated a superior ability to improve bone structure without showing significant synergy when combined with calcium.
Safety dosage
Adult from 12 years: 100 mL - 500 mL
Kefir is most often used in doses of 100 to 500 ml per day for 4 weeks.
Child from 1 year:
Preliminary clinical research suggests that a kefir-containing drink is safe when used for 10 days in children aged 1 to 5 years.
Interactions
Médicaments
Immunosuppressant: weak interaction
Kefir contains live bacteria and yeasts. Theoretically, they could pose risks for immunocompromised individuals.
Disulfiram: weak interaction
Kefir may contain alcohol. Theoretically, its consumption with disulfiram, a medication used to treat alcoholism, is not recommended. This interaction is considered minor but requires attention due to the possibility of adverse effects.
Precautions
Pregnant woman: use with caution
Probiotics, although generally recognized as safe, may carry risks when consumed in large quantities or by sensitive populations, such as pregnant women. It is therefore advised for pregnant women to consult a healthcare professional before incorporating kefir or any other new fermented product into their diet.
Breastfeeding woman: use with caution
Available data are insufficient.
Immunodeficiency: avoid
Kefir, known for its probiotic benefits, includes bacterial and yeast cultures that may pose theoretical risks for immunocompromised individuals. In these patients, the weakened immune system may less effectively manage these microorganisms, potentially increasing the risk of fungemia or bacteremia, meaning the presence of fungi or bacteria in the blood. It is advised that immunocompromised individuals avoid kefir consumption or use it with caution.
