Assessing the effects of kefir consumption in both healthy subjects and those with metabolic syndrome (MetS). Nutritional, Metabolic, Endocrine
Conditions
Interventions
Current interventions as of 26/01/2026:
The study aims to investigate the effects of kefir consumption in both healthy subjects and those with metabolic syndrome. Participants will be randomised using
Sponsors
Imperial College London
Eligibility
Sex/Gender
All
Age
18 Years to 65 Years
Inclusion criteria
Inclusion criteria: Healthy participants inclusion criteria: 1. General good health 2. Both gender 3. BMI between 20 and 29.9 kg/m2 4. Aged between 18 and 60 years old 5. Willing to take one daily portion of kefir or placebo and to follow the procedures as well as a 2-3h metabolic exploration day every month of follow-up 6. Written informed consent Metabolic syndrome participants inclusion criteria: 1. Aged between 18 and 65 years old 2. Subjects diagnosed with metabolic syndrome according to the International Diabetes Federation (IDF) criteria 3. Low consumption (max intake 3 servings/week) of kefir or supplements/foods labelled as having probiotic effect during the prior 3 months 4. Consumption of fruits and vegetables = 3 servings per day 5. Willing to take one daily portion of kefir or placebo and to follow the procedures as well as a 2-3h metabolic exploration day every month of follow-up 6. Written informed consent
Exclusion criteria
Exclusion criteria: Healthy participants exclusion criteria: 1. BMI =30 kg/m2 2. Gastrointestinal disorders of any kind 3. Previous abdominal surgery 4. Lactose intolerance or intolerance to the study products 5. Blood triglyceride > 150 mg/dL 6. Blood total cholesterol > 240 mg/dL or HDL-cholesterol 105 mg/dL 9. Pharmacological treatments of any type at enrolment and in the 2 months before the study 10. Consumption of supplements or foods labelled as having a probiotic effect prior 3 months 11. Consumption of Kefir > 3 servings/week during the prior 3 months 12. Menopause women 13. Alcohol consumption exceeding 30g of alcohol/day (1 alcoholic beverage dose = 10g of alcohol) or proven abuse or dependence on another drug. Consumption of more than 3 alcoholic beverages per day is considered abusive. An alcoholic beverage corresponds, for example, to 30 ml of spirits, 120 ml of wine or 330 ml of beer 14. Consumption of fruits and vegetables > 5 servings per day 15. Dietary fibre intake > 30g/1000 kcal per day 16. Pregnant, parturient or breast-feeding woman; for women of childbearing age: positive urine pregnancy test 17. Antibiotics consumption over the prior 1 month before the trial 18. Daily use of laxatives in the 3 months before explorations, or use of drugs that may strongly interfere with the composition of the intestinal microbiota 19. Contemporary participation in other studies 20. Blood donors in the last 2 months 21. Use of lipid-lowering drugs 22. Under antidiabetic treatment 23. Individuals who have lost/ gained = 3 kg in the last 3 months 24. Individuals with unstable medical or psychological conditions which, in the investigator's opinion, could lead the volunteer to be non-compliant or uncooperative during the study, or which could compromise the volunteer's safety or participation in the study 25. Pre-diabetes, type 1 or 2 diabetes 26. Cancer 27. Infectious diseases 28. Cardiovascular disease 29. Hypertension 30. Severe eating disorders (anorexia/bulimia, binge eating disorder, noctophagia, etc.) 31. Severe chronic renal failure (GFR<60mL/min) 32. Hepatocellular insufficiency 33. Exocrine pancreatic insufficiency 34. Known endocrine pathology inducing hyperglycaemia (uncontrolled dysthyroid, acromegaly, hypercorticism, etc.) 35. Previous intestinal or abdominal surgery, bariatric surgery, gallbladder surgery, polyp removal, known gastroparesis, total gastrectomy or colectomy 36. Pathology detectable on clinical examination and medical questioning that may interfere with the study's evaluation criteria 37. Adult subject to a legal protection measure (guardianship, curatorship) 38. Person deprived of liberty by judicial or administrative decision Metabolic syndrome participants exclusion criteria: 1. Lactose intolerance 2. Type 1 diabetes 3. Abnormal thyroid hormone levels 4. Chronic gastrointestinal system disease 5. Cancer 6. Severe liver disease 7. Kidney insufficiency 8. Immunodeficiency 9. Taking medication to regulate blood glucose (except metformin) or lipid levels (added 26/01/2026) for less than 3 months 10. Taking antibiotics prior to one month of the study 11. Taking supplement which may affect the metabolic outcomes such as prebiotic or omega-3 12. Dieting for weight loss or for another disease 13. Pregnant, parturient, or breast-feeding woman; for women of childbearing age: positive urine pregnancy t
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Current primary outcomes as of 26/01/2026: The effects of daily kefir consumption on markers of glucose metabolism in healthy volunteers are measured using fasting blood glucose (FG), glycated haemoglobin (HbA1C), and homeostasis model assessment-insulin resistance (HOMA-IR); and, in subjects with metabolic syndrome (MetS) are measured using insulin and homeostasis model assessment-insulin resistance (HOMA-IR), as follows: 1. Fasting blood glucose (FG) is measured using the PAP peroxidase method at baseline and monthly. 2. Glycated haemoglobin (HbA1C) is measured using capillary electrophoresis at baseline and month 3. 3. Homeostasis model assessment-insulin resistance HOMA-IR, calculated using the formula HOMA-IR = Fasting insulin (µU/mL) x fasting glucose (mg/dL)/405, is measured using Enzyme-Linked Immunosorbent Assay (ELISA) at baseline and monthly. Previous primary outcomes: The effects of daily kefir consumption on markers of glucose metabolism in healthy volunteers are measured using fasting blood glucose (FG), glycated haemoglobin (HbA1C), and homeostasis model assessment-insulin resistance (HOMA-IR); and, in subjects with metabolic syndrome (MetS) are measured using insulin and homeostasis model assessment-insulin resistance (HOMA-IR), as follows: 1. Fasting blood glucose (FG) is measured using the PAP peroxidase method at baseline and months 1, 2, 3, 4, 5, and 6 2. Glycated haemoglobin (HbA1C) is measured using capillary electrophoresis at baseline and months 3 and 6 3. Homeostasis model assessment-insulin resistance HOMA-IR, calculated using the formula HOMA-IR = Fasting insulin (µU/mL) x fasting glucose (mg/dL)/405, is measured using Enzyme-Linked Immunosorbent Assay (ELISA) at baseline and months 1, 2, 3, 4, 5, 6 | — |
Secondary
| Measure | Time frame |
|---|---|
| Current secondary outcomes as of 26/01/2026: 1. Measures of lipid metabolism (blood cholesterol, triglyceride, HDL cholesterol and LDL cholesterol) are measured by Nuclear Magnetic Resonance at baseline and month 4 in the healthy cohort, and at baseline and month 3 in participants with metabolic syndrome. 2. Inflammatory status (CRP, IL-6, IL-8, TNF-alpha and leptin) is measured using Enzyme-Linked Immunosorbent Assay (ELISA) at baseline and month 4 in the healthy cohort, and at baseline and month 3 in participants with metabolic syndrome. 3. Gut permeability and changes to the gut microbiome (microbial diversity, microbial composition) measured by metagenomics at baseline and monthly. Previous secondary outcomes: 1. Measures of lipid metabolism (blood cholesterol, triglyceride, HDL cholesterol and LDL cholesterol) are measured by Nuclear Magnetic Resonance at baseline and month 6 2. Inflammatory status (CRP, IL-6, IL-8, TNF-alpha and leptin) is measured using Enzyme-Linked Immunosorbent Assay (ELISA) at baseline and month 6 3. Gut permeability and changes to the gut microbiome (microbial diversity, microbial composition) measured by metagenomics at baseline and months 1, 2, 3, 4, 5, and 6 | — |
Countries
England, France, Italy, United Kingdom
Contacts
Public ContactYiwei Vally Wu
Outcome results
None listed