Kefir: benefits, dosage, contraindications
Family or group:
Probiotics, Superfood
Active ingredients:
Lactic ferments
Lactobacilli
Indications
Scoring 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 there was an association between these products and reduced levels of C-reactive protein (CRP), a key marker of inflammation. This reduction indicates that kefir could help mitigate inflammation associated with conditions such as cardiovascular disease and metabolic syndrome. In addition, a study of overweight or obese women showed that adding two servings of kefir to a weight-maintenance diet for eight weeks promoted greater weight loss than 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 randomized to receive daily either 180 mL of kefir or an equivalent volume of non-fermented milk for 12 weeks. Results revealed a significant 3.4% increase in serum ApoA1 concentrations in the kefir group, while concentrations decreased by 2.4% in the milk group. An increase in ApoA1 levels is often considered beneficial for cardiovascular health, ApoA1 being the main component of high-density lipoproteins (HDL), often referred to as "good cholesterol".
Posologie
Oral
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 in patients with Helicobacter pylori infection shows that taking 250 mL of kefir twice daily for two weeks increases the H. pylori eradication rate by 56% compared with placebo milk. All patients also received triple therapy consisting of lansoprazole, amoxicillin, and clarithromycin.
Posologie
Oral
500 mL
2 - weeks
Chronic inflammatory bowel diseases ✪✪✪✪✪
Kefir, a fermented dairy product, has been studied for its potential effects in the management of chronic inflammatory bowel diseases, notably Crohn's disease and ulcerative colitis. A small clinical study in adults with Crohn's disease found that consuming 200 mL of kefir twice a day for four weeks reduced feelings of bloating and improved overall symptoms compared with baseline. However, these results should be interpreted with caution due to the absence of a control group.
Posologie
Oral administration
400 mL
4 weeks
Digestive disorders ✪✪✪✪✪
Kefir, known for its probiotic properties, shows promising therapeutic potential in the treatment of dyspepsia. A study in adults with Crohn's disease showed that consuming 200 mL of kefir twice a day for four weeks significantly reduces feelings of bloating and improves overall symptoms. In addition, consuming kefir during pregnancy may decrease the risk of developing an allergy to cow's milk proteins in children up to three years of age. Further research by Steven R. Hertzler and Shannon M. Clancy has shown that kefir improves lactose digestion and reduces intolerance symptoms such as flatulence, suggesting greater lactase activity in kefir compared with milk. Another pilot study in Turkey observed an improvement in chronic constipation symptoms, with increased stool frequency and faster transit in patients with slow transit.
Posologie
Oral administration
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
Kefir, naturally rich in probiotics, is beneficial for digestive health, as demonstrated by a study in patients with inflammatory bowel diseases. This research highlighted the positive influence of regular kefir consumption on the gut flora and the quality of life of patients suffering from ulcerative colitis and Crohn's disease. Kefir provides Lactobacilli, which are essential for a balanced intestinal microbiota. In addition, participants reported an improvement in digestive symptoms such as bloating and an increase in the overall sense of well-being, indicating not only an improvement in digestive function but also a positive impact on psychological well-being. Moreover, kefir has demonstrated the ability to accelerate colonic transit, particularly in patients with slow transit. These effects are likely due to kefir's richness in microorganisms, 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 in particular kefiran, are active against various acute inflammations such as colitis, reducing inflammatory markers such as TNFα and IL-8. They act by modulating pro-inflammatory cytokines and by inhibiting pathways such as NF-κB, which is essential in inflammatory processes. Kefiran has shown significant effects in mouse models of colitis, attenuating weight loss and damage to colonic tissue. This efficacy is comparable to that of common drug treatments such as prednisolone. In addition, kefir acts on the intestinal barrier by increasing the expression of occlusion proteins such as occludin and claudin-1, thus strengthening the intestinal mucosal integrity. Kefir has also demonstrated anticancer properties, notably against breast, colon, and liver cancers. Kefiran reduced the viability of cancer cells, with dose-dependent effects observed in various in vitro studies.
Usages associés
Antimicrobial
Kefir, thanks to its bioactive components, notably exopolysaccharides (EPS) such as kefiran, and organic acids like lactic acid, 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 shown effectiveness against bacteria such as Escherichia coli and Staphylococcus aureus, by 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 exhibit antimicrobial properties by directly attacking the cell membranes of pathogens. These peptides, produced by species such as Lactobacillus paracasei, are capable of disorganizing the lipid structures of bacterial membranes, leading to leakage of vital cellular components and bacterial death.
Cardiovascular
The bioactive compounds in kefir play an essential role in modulating cardiovascular health by positively influencing glucose metabolism and the lipid profile. Research has shown that kefir may improve markers of diabetes and obesity, although results are sometimes mixed. For example, in murine models of diabetes and obesity, administration of kefir did not change plasma glucose levels, but significantly reduced the weight of adipose tissue and decreased the expression of pro-inflammatory and fatty acid synthesis genes in adipocytes. This suggests a 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 acid bacterial strains, has 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 preventing osteoporosis in an experiment with ovariectomized mice, simulating the decline in estrogen levels seen in postmenopausal women. These peptides significantly increase bone mineral density, as well as mechanical properties such as the modulus of elasticity and bone hardness. Compared with standard treatment with calcium carbonate, kefir peptides demonstrated a superior ability to improve bone structure, without showing significant synergy when combined with calcium.
Safe dosage
Adults aged 12 years and older: 100 mL - 500 mL
Kefir is most often used at doses of 100 to 500 mL per day for 4 weeks.
Children aged 1 year and older:
Preliminary clinical research suggests that a kefir-containing beverage is safe when used for 10 days in children aged 1 to 5 years.
Interactions
Médicaments
Immunosuppressant: low interaction
Kefir contains live bacteria and yeasts. Theoretically, they could pose risks for immunocompromised individuals.
Disulfiram: low interaction
Kefir may contain alcohol. Theoretically, consuming it with disulfiram, a medication used to treat alcoholism, is not recommended. This interaction is considered minor but warrants attention due to the possibility of adverse effects.
Precautions
Pregnant women: use with caution
Probiotics, although generally recognized as safe, may carry risks when consumed in large amounts or by sensitive populations, such as pregnant women. Therefore, pregnant women are advised to consult a healthcare professional before adding kefir or any other new fermented product to their diet.
Breastfeeding women: use with caution
Available data are insufficient.
Immunodeficiency: avoid
Kefir, known for its probiotic benefits, contains cultures of bacteria and yeasts that may pose theoretical risks for immunocompromised individuals. In these patients, a weakened immune system could be less able to control these microorganisms, potentially increasing the risk of fungemia or bacteremia, that is, the presence of fungi or bacteria in the blood. Immunocompromised individuals are advised to avoid consuming kefir or to use it with caution.
