Effects of Milk-based Drinks on Gut Microbiome, Sleep and Cardiometabolic Markers

NCT07071181 | Recruiting

• 2 other identifiers: ER72870766Other
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 2

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. 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. 2.Does repeated ingestion of kefir impact LDL, triacyglycerols and non-HDLc in adults with sleep problems?
3. 3.What effect does repeated ingestion of kefir have on cognitive function and mood?
4. 4.What effect does repeated ingestion of kefir have on vascular function, inflammation and markers of immunity in adults with sleep problems?

Conditions

Sleep; Cardiovascular Diseases; Gut Microbiome; Cognitive Function and Mood; LDL Cholesterol

Outcome Measures

Primary Outcomes (3)

• LDL Cholesterol

  A blood sample via venepuncture will be taken at baseline and again after 4-weeks of daily consumption of the intervention or control for the assessment of LDL cholesterol. Blood samples will be obtained in a fasted state.

  4-weeks

• Gut microbiome

  A stool sample will be collected from participants at baseline and after 4 weeks daily consumption of the intervention and control drink. The composition of the microbiome in stool will be measured by 16s rRNA sequencing.

  4-weeks

• Sleep quality and duration

  Sleep quality and duration will be measured objectively and subjectively. For subjective measures, the Pittsburg Sleep Quality Index will be used to assess participant's sleep habits. The tool comprises of 7 sub-components and 18 items, including subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. In addition, the Epworth Sleepiness Scale. The Epworth sleepiness scale results range from 0 to 24. Participants will also wear a Fitbit Charge 2 watch to track their sleep. Sleep measures will be obtained during the 7-day run in and final week of each study intervention for a total of 4 questionnaires to be completed by each participant and 4 week of objective sleep data.

  4-weeks

Secondary Outcomes (5)

• Blood samples

  4-weeks

• Cognitive function

  4 weeks

• Blood pressure

  4 week

• Pulse Wave Analysis

  4 week

• Saliva IgG

  4 week

Other Outcomes (4)

• Small intestine bacteria composition

  From ingestion of capsules to their excretion

• Dietary Patterns

  4 days

• Additional questionnaires

  4-weeks

Study Arms (2)

Original Kefir

ACTIVE COMPARATOR

250ml of original kefir

Dietary Supplement: Original flavour kefir

Milk

SHAM COMPARATOR

250 ml of milk

Other: Milk

Interventions

Original flavour kefir DIETARY_SUPPLEMENT

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".

Original Kefir

Milk OTHER

Participants will consume 250 ml milk daily for 4 weeks. This milk will not contain any live cultures.

Milk

Eligibility Criteria

• Age: 40 Years - 70 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Sheffield Hallam University: lead
• Biotiful: collaborator
• University of Leeds: collaborator
• Nimble Science Ltd.: collaborator

Study Sites (2)

University of Leeds

Leeds, West Yorkshire, LS29JT, United Kingdom

NOT YET RECRUITING

College of Health, Wellbeing and Life Sciences

Sheffield, S1 1WB, United Kingdom

RECRUITING

MeSH Terms

Conditions

Cardiovascular Diseases

Interventions

Milk

Intervention Hierarchy (Ancestors)

Beverages; Diet, Food, and Nutrition; Physiological Phenomena; Dairy Products; Food; Food and Beverages

Study Officials

• Tony Lynn, PhD

  Sheffield Hallam University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Tony Lynn,, PhD

CONTACT

0114 2252065; T.lynn@shu.ac.uk

Lucy Ellis, PhD

CONTACT

Lucy.Ellis@shu.ac.uk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Dr Anthony Lynn

Model Details: This trial conforms to a randomised, double-blind, 2 arm crossover. Participants will consume the active drink or a control drink for 4 weeks before crossing over to the opposite condition after a 4-week washout. Order of drink allocation will be counterbalanced.

Study Record Dates

• First Submitted: July 9, 2025
• First Posted: July 17, 2025
• Study Start: August 1, 2025
• Primary Completion: March 1, 2026
• Study Completion: March 1, 2026
• Last Updated: July 17, 2025

Record last verified: 2025-06

Data Sharing

• IPD Sharing: Will not share

Locations

GB (2)