Effects of an Evening PROtein PrEload on Metabolic Health in Night ShIfT Workers (PROPENSITy)

Study Overview
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Brief Summary
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This study will compare the effects of a whey protein supplement or a placebo consumed before the evening meal on health outcomes in night shift workers.

Detailed Description
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Participants are assigned in random order to two conditions, for 12 days each. The interventions are 1) a 30g whey protein preload consumed 1-1.5 hr prior to their main evening meal every day for 12 days. No other advice will be given. 2) an identical mixed-nutrient drink matched for caloric content, taste and palatability consumed 1-1.5 hr prior to their main evening meal every day for 12 days(placebo). Conditions are separated by a 2-week washout period, during which participants will be encouraged to maintain their habitual diet and physical activity levels. Metabolic testing will be performed at baseline, and at the end of both conditions.

Official Title
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Effects of an Evening PROtein PrEload on Blood Glucose, Metabolic Health, and Gut Hormone Release in Night ShIfT Workers (PROPENSITy)

Conditions
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Type 2 Diabetes, Shift-work Disorder

Intervention / Treatment
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* Dietary Supplement: whey protein
* Dietary Supplement: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Female Night shift workers (with a minimum of 6 months in their current shift work schedule) 35-65 years BMI 28.0-35.0 kg/m2; waist circumference > 80cm Weight stable in the past 6 months Exclusion Criteria: Those working standard day time hours only, or those who work less than three to four night shifts per fortnight on average Personal history and/or diagnosis of: diabetes, cancer, major psychiatric disorders, liver disease, gastro-intestinal surgery or disease (including malabsorption), eating disorders, anaemia, insomnia or cardiovascular disease, and/or any other condition deemed unstable by the study physician Taking medications known to alter body composition or metabolism, including (but not limited to): any medication used to lower blood glucose or antidiabetic medications (metformin, sulfonylureas, Glucagon-like peptide-1 (GLP-1) analogues [i.e. exenatide], thiazolidinediones or DPP-IV inhibitors [i.e. 'gliptins']), medications affecting weight, appetite or gut motility (i.e. diuretics, domperidone, cisapride, orlistat, phentermine, topiramate) Participants who are taking stable doses (i.e. > 12 months) of androgenic medications (i.e. testosterone) or SSRI's will not be excluded. Personal history/diagnosis (self-reported) of diabetes (type 1 or 2), major psychiatric disorders (schizophrenia, major depressive disorder, bipolar disorder, eating disorders), gastrointestinal disorders, haematological disorders (i.e. thalassemia, iron-deficiency anaemia) insomnia, or any other medical condition, deemed unstable by the study physician Pregnant, planning a pregnancy or breastfeeding Those who have lost or gained >5% of body weight in the last 6 months Those who consume four or more standard drinks on a single occasion at a 'daily or almost daily' occurrence current smokers of cigarettes/marijuana/e-cigarettes/vaporisers unable to comprehend the study protocol (i.e. due to English language or cognitive difficulties)

Ages Eligible for Study
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Minimum Age: 35 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Whey protein preload condition<br>Participants will consume 30 g whey protein isolate powder (dissolved in water) 1-1.5 hr prior to their main evening meal every day for 12 days. | Dietary Supplement: whey protein<br>* Protein drink containing 30g whey protein isolate powder (dissolved in water) consumed 1-1.5 hr prior to their main evening meal every day for 12 days, No other advice will be given.<br>|
| Placebo Comparator: Placebo condition<br>Participants will consume an energy-matched mixed-nutrient placebo drink 1-1.5 hr prior to their main evening meal every day for 12 days, | Dietary Supplement: Placebo<br>* Energy-matched mixed-nutrient placebo drink consumed 1-1.5 hr prior to their main evening meal every day for 12 days. No other advice will be given.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glycaemic response | Change in glucose (AUC) following a standard breakfast | 12 days (3 hours meal test) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 24-hour glucose profiles | Change in 24-hour glucose profiles assessed by continuous glucose monitoring | 12 days | 
| Glucose variability | Change in 24-hour glucose variability (as SD, standard deviation) assessed by continuous glucose monitoring | 12 days | 
| Glucose variability | Change in 24-hour glucose variability (as CV, coefficients of variation) assessed by continuous glucose monitoring | 12 days | 
| Glucose variability | Change in 24-hour glucose variability (as MAGE, mean amplitude of gylcaemic excursions) assessed by continuous glucose monitoring | 12 days | 
| GLP-1 | Change in GLP-1 (AUC) following a standard breakfast | 12 days (3 hours meal test) | 
| GIP | Change in GIP (AUC) following a standard breakfast | 12 days (3 hours meal test) | 
| glucagon | Change in glucagon (AUC) following a standard breakfast | 12 days (3 hours meal test) | 
| Insulin | Change in fasting and postprandial insulin following a standard breakfast | 12 days | 
| Ghrelin | Change in ghrelin (AUC) following a standard breakfast | 12 days (3 hours meal test) | 
| PYY | Change in YY (AUC) following a standard breakfast | 12 days | 
| Adiponectin | Change in fasting adiponectin | 12 days | 
| C-Reactive Protein (CRP) | Change in fasting CRP | 12 days | 
| Blood lipids | Changes in blood lipid profile (total cholesterol, HDL-, LDL-cholesterol and triglycerides) | 12 days | 
| Blood pressure | Changes in systolic blood pressure and diastolic blood pressure | 12 days | 
| Resting metabolic rate | Changes in resting metabolic rate | 12 days | 
| respiratory quotient | Changes in respiratory quotient | 12 days |