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

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.

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.

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.

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.

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.

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.

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

Participants will be asked to provide a saliva sample after a 10 minute mouth rinse with water. Saliva samples will be analysed for IgA using ELISA.

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.

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.

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.

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.