Bifidobacterium strains with potential health benefits can contribute to the gastrointestinal wellbeing. However, the ability of these strains to survive gastro-intestinal tract stress and their impact on gut microbiome remains to be clarified. Moreover, prebiotic fibres, such as galacto-oligosaccharides (GOS) can promote the proliferation of Bifidobacteria. This is why the current study aims to assess the impact of Bifidobacteria consumption on human gut microbiome with or without GOS compared to control product.

Inclusion Criteria:

1. Male and female subjects aged between 45 and 60 years old.

2. BMI between 18.5 kg/m2 and 30 kg/m2.

3. Subjects who are overtly healthy as determined by the investigator.

4. Willing and/or able to:

   • Speak and read in French,
   • Collect, store and transport their faecal samples themselves,
   • Consume the study products twice per day for 28 consecutive days and not to consume any fermented dairy products during the entire study (other than the study products) as well as any probiotic, prebiotic or synbiotic supplements during the entire study.
   • Complete the electronic Patient Reported Outcomes (ePRO) using their own digital device having access to internet.

5. Willing to limit alcohol consumption and not to smoke or consume any soft or hard drug during the study.

6. Having access to adequate space to store the investigational products in their own fridge at home.

7. Having regular bowel movements.

8. Signed written informed consent by the participant.

9. Female subjects must either be postmenopausal for at least 12 months or have undergone specific surgical procedures resulting in sterility or they are using one of the medically approved contraceptive methods.

10. Subject is covered by French health insurance.

11. Subject agrees to be registered in the national database of subjects participating in clinical research.

Exclusion Criteria:

1. Any ongoing metabolic disease, hypertension, inflammatory disease, allergic conditions requiring chronic systemic medication, psychiatric disorder, gastrointestinal disorder, chronic pain, or neurological disorder diagnosed by a physician.
2. Known allergy or intolerance to any ingredients or potential allergens.
3. Pregnancy or breast-feeding at the screening visit or plan for pregnancy during the study.
4. Any antecedents or plan for digestive or dental surgery, general anaesthesia or any participation in another study with investigational or marketed products potentially affecting the gut microbiota.
5. Unable (or unwilling) to adhere to protocol requirements (based on investigator's judgement).
6. Subject with a special diet at the screening visit, or plan for such diet during the study.
7. Major changes in subject's dietary habits ≤ 4 weeks before the screening visit or plan for such major changes during the study including change in vitamin or mineral supplements use, but except for dietary restrictions related to the study.
8. Enhanced diet together with intense physical activity ≤ 4 weeks before the screening visit, plan for such a diet and training during the study, or plan for major changes in physical activity during the study.
9. Use ≤ 8 weeks before the screening visit or plan of use during the study of systemic medication that can affect the gastrointestinal function or plan of use during the study (if needed, incidental use of ≤ 4 tablets of paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs) or aspirin per 2-week period is allowed).
10. Subject with excessive alcohol consumption, active smoker or quit active smoking less than 5 years ago before the screening visit. Not regularly smoking is allowed.
11. Drug abuse based on investigator's judgement.
12. Living in the same home as others already participating in the study and to concomitantly receive some study products.
13. Subject under guardianship, curatorship, person under judicial protection, family empowerment or future protection mandate.
14. Employees, family members or other relatives of employees of the participating centre or of Danone Global Research & Innovation Center.