Exploring how probiotics affect energy metabolism after meals in older adults

Inclusion Criteria:

1. Man or woman;
2. Age between 50 and 70 years old (inclusively);
3. Postmenopausal women, i.e. with amenorrhea for more than a year with no identified cause
4. BMI between 27 and 34.9 kg/m2 (inclusively);
5. Stable weight in the last 3 months (+/- 5% of total body weight);
6. Waist circumference ≥ 80 cm for women, ≥ 94 cm for men;
7. Sedentary to moderately active (less than 30 minutes of moderate physical activity, 3 times a week);
8. Agreeing not to consume fermented or supplemented foods (including bifidus yogurts and other foods supplemented with probiotics), dietary supplements (high in fiber (prebiotics), high protein, or other food supplements that may interact with the gut microbiota or energy metabolism), laxatives and any substance that can control metabolic parameters such as weight, blood glucose or lipid metabolism during the study period (from the screening visit);
9. Agreeing to receive probiotics or placebo supplementation randomly;
10. Able to understand the information given, read and write in French and have signed the informed consent form;
11. Agreeing to submit to the entire study protocol;
12. Having fibre consumption (through diet or supplementation) of less than 30g/day;
13. Having a freezer to store stool samples before the visit.

Exclusion Criteria:

1. Participant with unstable medical or psychological conditions that, in the opinion of the investigator, could lead the participant to be non-compliant or uncooperative during the study or that could compromise the safety or participation in the study (according to articles L.1121-6, L.1121-8, L.1121-9 and L1122-1-2 of the Public Health Code);
2. Presence of pathology detectable on clinical examination and medical questioning that may interfere with the study endpoints;
3. Alcohol consumption exceeding 30g of alcohol/day (1 dose of alcoholic beverage = 10g of alcohol) or abuse or dependence on another proven drug;
4. Tobacco consumption (or vaping equivalent) \> to 5 cigarettes per day and inability to restrict smoking or vaping on the exploratory days provided for in the protocol;
5. Failure to comply with the exclusion period for another study specified in the "national volunteer file";
6. Adult subject to a legal protection measure (guardianship, curatorship);
7. Person deprived of liberty by a judicial or administrative decision;
8. Person who has exceeded the annual amount of compensation in the year for participation in research protocols;
9. Person not affiliated to a social security system or beneficiary of a similar system;
10. Absence of valid approved health proof(s) in the event of government measures in an exceptional epidemic situation;
11. Person with a specific diet (vegetarian, lacto-vegetarian, vegan, high-protein, etc.);
12. People consuming food supplements (pre or probiotics, or minerals (divalent cations such as magnesium and calcium)) regularly during the month prior to the screening visit;
13. Blood donation within 2 months prior to the screening visit;
14. Claustrophobic to the point that indirect calorimetry measurement cannot be done;
15. Person with limited venous access that can make it difficult to draw blood and insert a catheter;
16. Type 1 or 2 diabetes;
17. Systolic blood pressure ≥140 mmHg measured during the screening visit and mean systolic blood pressure from self-measurement over 3 days ≥140 mmHg;
18. Diastolic blood pressure≥ 90 mmHg measured during the screening visit and mean diastolic blood pressure from self-measurement over 3 days ≥90 mmHg;
19. Treatment for hypertension or dyslipidemia;
20. Known endocrine pathology that may interfere with carbohydrate metabolism (uncontrolled dysthyroidism, acromegaly, hypercorticism, etc.);
21. People with gastrointestinal pathologies with an inflammatory component or associated with malabsorption;
22. People suffering from bloody diarrhoea;
23. Exocrine pancreatic insufficiency;
24. People who have had intestinal or abdominal surgery (apart from appendectomy and simple hernias), bariatric surgery (gastric banding, calibrated vertical gastroplasty and sleeve gastrectomy accepted if done more than 5 years ago);
25. Severe eating disorders (e.g., anorexia/bulimia, uncontrolled binge eating syndrome, noctophagia);
26. Chronic kidney failure;
27. Hepatocellular insufficiency;
28. Immunocompromised individuals (e.g., those with AIDS, lymphoma, patients on long-term corticosteroid therapy, patients undergoing chemotherapy and allogeneic transplants);
29. Patients with central venous catheters and post-surgical patients;
30. Hematological, gastrointestinal, hepatic, neurological, or psychiatric clinically significant according to the investigator;
31. Drug treatments for obesity in the last 3 months or prescribed for the duration of the study;
32. Taking antibiotics in the month preceding the explorations (for the so-called common antibiotics of the beta-lactam family) or in the 3 months preceding the explorations according to the investigator's judgment (for other families of antibiotics) except for certain types of antibiotics, particularly local or single-dose antibiotics: antibiotic eye drops (Oflocet), topical ointments (Fucidin), single-dose treatments (Monuril), and single-dose fosfomycin;
33. Taking antidepressants in the 2 months prior to the explorations or prescribed for the duration of the study;
34. Daily intake of laxatives in the 3 months prior to explorations or other medications that may strongly interfere with the composition of the gut microbiota;
35. Taking a treatment that may interfere with the study measures, according to the judgment of the co-investigating physicians of the study.