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

ConditionsSleep Cardiovascular Diseases Gut Microbiome Cognitive Function and Mood LDL Cholesterol

Trial statusRecruiting

Trial phaseNot applicable

Trial typeInterventional

Biological sexAll

Age40-70

SponsorSheffield Hallam University

About this trial

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

This trial accepts healthy volunteers

Qualifiers

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

Disqualifiers

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

Trial design

Design model

Crossover

Treatments tested in this trial

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

Treatment groups

40 Participants

are divided into 2 treatment groups

Group A: Original KefirActive comparator 1 intervention

Group B: MilkSham comparator 1 intervention

Trial outcomes

Primary outcomes

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.

Time frame

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.

Time frame

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.

Time frame

4-weeks

Secondary outcomes

Blood samples

Serum or plasma samples will be obtained via venepuncture for the measurement of insulin, fasting blood glucose, lipids (LDL, HDL), triglycerides, iCAM, vCAM, CRP, and IL-6. All measurements will be taken in a fasted state at each intervention day.

Time frame

4-weeks

Cognitive function

A cognitive test battery consisting of 3 cognitive tests will be used to investigate the effect of the intervention or control on cognitive function. Participants mood will also be assessed using the Positive and Negative Affect Schedule (PANAS) questionnaire that asks participants to rate a series of adjectives describing both positive and negative emotions.

Time frame

4 weeks

Blood pressure

Blood pressure (systolic blood pressure, diastolic blood pressure and heart rate) will be measured in triplicate using a Vicorder after the paritipcant has rested for 15 minutes upon arrival to the lab. All measurements will be taken in a fasted state.

Time frame

4 week

Pulse Wave Analysis

Carotid to femoral Pulse Wave Velocity (PWV) and Augmentation Index (Aix) will be measured using a Vicorder.

Time frame

4 week

Other outcomes

Small intestine bacteria composition

A subsample of participants will be instructed to ingest SIMBA capsules. Upon retrieval, the capsules will be analysed for the composition of microbiome in capsule fluid by 16s rRNA sequencing and the composition of metabolome in capsule fluid by NMR metabolomics. Capsules will be ingested at baseline and at 4-week time frame in each arm.

Time frame

From ingestion of capsules to their excretion

Dietary Patterns

During the course of the study, participants will be asked to maintain their normal dietary habits. Participants are asked to record their food and drink consumption for 4-days. This food record will be obtained 4-day prior to each intervention arm and 4-day prior to finishing each intervention arm.

Time frame

4 days

Additional questionnaires

The Gastrointestinal Symptom questionnaire comprises 15 items in 5 sections: abdominal pain, reflux, indigestion, diarrhea and constipation. Questionnaire responses will be collected at baseline and after 4 week of ingestion of each study drink. In addition, a palatability questionnaire (Visual analogue scale) will be given to the participants at the end of each arm.

Time frame

4-weeks

Body composition

Height and weight will be measured at each study visit for the purpose of BMI calculation. In addition Bioelectrical impedance analysis (BIA) will be used to measure fat-free mass, total body water, percent fat, body cell mass, intracellular water, and extracellular water.

Time frame

4 week