Effects of Milk-based Drinks on Gut Microbiome, Sleep and Cardiometabolic Markers
Trial Parameters
Brief 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 Criteria
Inclusion Criteria: * 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 Criteria: * 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