Effects of Milk-based Drinks on Gut Microbiome, Sleep and Cardiometabolic Markers
A Randomised, Double-blind Trial to Measure the Effects of Milk-based Drinks on Gut Microbiome, Sleep, and Cardiometabolic Markers in Adults With Poor Sleep
Sheffield Hallam University
40 participants
Aug 1, 2025
INTERVENTIONAL
Conditions
Summary
The purpose of this study is to evaluate the effects of kefir on gastrointestinal health, sleep quality, and biochemical parameters in adults who have sleep problems. Further measurements of cognitive function, arterial stiffness and blood pressure will also be assessed. The following questions will be addressed during the study: 1. What effect does repeated ingestion of kefir have on the gut microbiome and can this positively influence sleep performance (quality and duration) in adults with sleep problems? 2. Does repeated ingestion of kefir impact LDL, triacyglycerols and non-HDLc in adults with sleep problems? 3. What effect does repeated ingestion of kefir have on cognitive function and mood? 4. What effect does repeated ingestion of kefir have on vascular function, inflammation and markers of immunity in adults with sleep problems? In a randomised, crossover design study, participants will consume 250 ml of kefir (original flavour) or milk for 4 weeks with a 4-week washout.
Eligibility
Inclusion Criteria5
- Aged 40-70 years old
- Suffer with poor sleep (measured using the PIttsburg Sleep Quality Index with a score > 5)
- BMI in range of 25-35 kg/m2
- Willingness to consume each study drink daily for 4 weeks and attend the laboratory on 4 separate occasions
- For women: Medication in the form of contraception or HRT providing these have not been modified 3 months prior to the first study day
Exclusion Criteria5
- Intolerance or allergy to milk-based products
- Pregnancy/breastfeeding
- Insufficient English language skills to complete all study questionnaires and perform the cognitive tests
- Gastrointestinal disorders
- Inability to attend the laboratory due to travel/mobility difficulties
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Interventions
Participants will consume 250ml of original flavour kefir daily for 4 weeks. According to the manufacturer, "packed with billions of live cultures to support Gut health".
Participants will consume 250 ml milk daily for 4 weeks. This milk will not contain any live cultures.
Locations(2)
View Full Details on ClinicalTrials.gov
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NCT07071181