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Trial registered on ANZCTR


Registration number
ACTRN12617000403336
Ethics application status
Approved
Date submitted
30/09/2015
Date registered
17/03/2017
Date last updated
23/01/2019
Date data sharing statement initially provided
23/01/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
Effects of A1 versus A2 milk on cardiometabolic risk in overweight and obese Australians
Scientific title
Overweight and obese Australians and the effects of A1 beta-casein versus A2 beta-casein on human cardiometabolic risk factors.
Secondary ID [1] 287573 0
None
Universal Trial Number (UTN)
U1111-1194-2629
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Overweight and obesity 296359 0
Cardiometabolic risk factors related to A1 beta-casein 296360 0
Gastrointestinal symptoms related to A1 beta-casein 302488 0
Condition category
Condition code
Cardiovascular 296633 296633 0 0
Diseases of the vasculature and circulation including the lymphatic system
Diet and Nutrition 296634 296634 0 0
Obesity
Inflammatory and Immune System 302047 302047 0 0
Other inflammatory or immune system disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
All participants will undergo a washout period of 2 weeks during which they will replace all dairy with rice milk. Other dairy containing product consumption will be restricted.

Intervention 1: 250ml three times a day (750 ml/day) A1A2 beta-casein Milk for 12 weeks
Intervention 2: 250ml three times a day (750 ml/day) A2A2 beta-casein Milk for 12 weeks

Adherence will be monitored via a milk intake calendar
Intervention code [1] 292975 0
Treatment: Other
Comparator / control treatment
Control: 250ml three times a day (750 ml/day) Rice Milk for 12 weeks

Adherence will be monitored via a milk intake calendar
Control group
Active

Outcomes
Primary outcome [1] 296254 0
Fasting serum cholesterol
Timepoint [1] 296254 0
Pre-washout, baseline and 12 weeks.
Primary outcome [2] 296255 0
Fasting serum triglyceride
Timepoint [2] 296255 0
Pre-washout, baseline and 12 weeks.
Primary outcome [3] 296256 0
Antibodies to oxidised LDL measured by ELISA
Timepoint [3] 296256 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [1] 317985 0
Fasting serum inflammatory markers (Glutathione, MPO, IL-4, IL-6, IL-8, CRP, TNF-alpha, IFN-gamma and TGF-beta1
Timepoint [1] 317985 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [2] 317986 0
Fasting serum insulin
Timepoint [2] 317986 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [3] 317987 0
Blood pressure measured by automated, calibrated sphygmomanometer
Timepoint [3] 317987 0
Pre-washout, baseline and 12 weeks
Secondary outcome [4] 317988 0
Fasting serum leptin
Timepoint [4] 317988 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [5] 317989 0
Body composition measured by dual-energy X-ray absorptiometry (DXA)
Timepoint [5] 317989 0
Baseline and 12 weeks
Secondary outcome [6] 317990 0
Gut permeability measured by dual sugar test (Lactulose/Mannitol)
Timepoint [6] 317990 0
Baseline and 12 weeks
Secondary outcome [7] 317991 0
Gut inflammation measured by assesing faecal calprotectin with a single step enzyme linked immunosorbant assay (ELISA)
Timepoint [7] 317991 0
Baseline and 12 weeks
Secondary outcome [8] 317992 0
A1A2, A2A2 and Rice milk tolerance measured by GI symptom report diary
Timepoint [8] 317992 0
Baseline, 6 weeks and 12 weeks
Secondary outcome [9] 317993 0
Body weight will be recorded in light clothing without shoes with a Body Composition Monitor (Omron Healthcare, Kyoto, Japan)
Timepoint [9] 317993 0
Pre-washout, baseline and 12 weeks
Secondary outcome [10] 332800 0
Fasting serum glucose
Timepoint [10] 332800 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [11] 332801 0
Fasting whole blood Hba1C
Timepoint [11] 332801 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [12] 332802 0
Arterial stiffness assessed by pulse contour analysis using the Pulse Trace PCA 2 (Carefusion, NSW, Australia)
Timepoint [12] 332802 0
Pre-washout, baseline and 12 weeks
Secondary outcome [13] 332803 0
Satiety will be assessed by 100 mm Visual Analogue Scale (VAS) questionnaires
Timepoint [13] 332803 0
Baseline and 12 weeks
Secondary outcome [14] 332804 0
Waist circumference will be measured in the standing position at the narrowest area between the lateral lower rib and the iliac crest with a tape measure.
Timepoint [14] 332804 0
Pre-washout, baseline and 12 weeks
Secondary outcome [15] 332805 0
Hip circumference will be taken at the largest circumference of the lower abdomen with a tape measure.
Timepoint [15] 332805 0
Pre-washout, baseline and 12 weeks
Secondary outcome [16] 332806 0
Plasma BCM-7 will be assessed by ELISA and cross-checked with HPLC MS
Timepoint [16] 332806 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [17] 332807 0
Fasting serum Non-Esterified Fatty Acids (NEFA)
Timepoint [17] 332807 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [18] 332808 0
Fasting serum Dipeptidyl Peptidase-IV (DPPIV) activity
Timepoint [18] 332808 0
Pre-washout, baseline and 12 weeks.
Secondary outcome [19] 332809 0
Psychological health (quality of life, psychological well-being, self-rated health, and anxiety and depression) will be measured using previously-validated self-report psychometric inventories.
Timepoint [19] 332809 0
Baseline and 12 weeks
Secondary outcome [20] 332810 0
Executive Functioning will be assessed by the Subtle Cognitive Impairment Test (SCIT)
Timepoint [20] 332810 0
Baseline and 12 weeks
Secondary outcome [21] 332822 0
Short Chain Fatty Acids (SCFA) in faecal samples will be analysed
Timepoint [21] 332822 0
Baseline and 12 weeks
Secondary outcome [22] 332823 0
Gut microbiome will be analysed from faecal samples
Timepoint [22] 332823 0
Baseline and 12 weeks

Eligibility
Key inclusion criteria
overweight or obese (BMI: 25-40 kg/m2)
willing to consume 750 ml of milk/day
Minimum age
18 Years
Maximum age
70 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Milk allergy, pregnancy and lactation, diabetes, current habitual opioid consumption and smokers

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Eligible participants will be assigned an ID as they are recruited. Allocation will involve contacting the holder of the allocation schedule who will be off-site.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The randomisation scheme will be created using www.randomization.com with 3 treatments.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
A sample size of 32 participants/group is predicted to provide sufficient power (80%) to detect a large effect size (7% difference) between groups at the p < 0.05 level. Recruiting 46 participants/group will accommodate for 30% dropout rate. A total of 140 participants will be recruited for the 3 groups. Calculations are based on standard deviation of 10% within a group observed in our previous studies examining changes in cardiometabolic risk factors in overweight and obese participants. Statistical analysis will be undertaken using SPSS 22 for Windows (SPSS Inc., Chicago, IL). Data will be expressed as mean (+/-SEM) and assessed for normality to ensure that the assumptions of the analysis are met. The data will be analysed using General Linear Models with baseline value covariates. If significant between groups effects are present, post hoc comparisons between the treatment groups will be made using the Least Significant Difference (LSD) method. Statistical significance will be considered at p<0.05.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
WA

Funding & Sponsors
Funding source category [1] 292144 0
Commercial sector/Industry
Name [1] 292144 0
The a2 milk Company
Address [1] 292144 0
PO Box 1564 North Sydney
NSW 2059
Country [1] 292144 0
Australia
Primary sponsor type
University
Name
Curtin University
Address
GPO Box U1987 Perth
WA 6845
Country
Australia
Secondary sponsor category [1] 290819 0
None
Name [1] 290819 0
Address [1] 290819 0
Country [1] 290819 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 293621 0
Curtin Human Research Ethics Committee
Ethics committee address [1] 293621 0
GPO Box U1987, Perth
Western Australia, 6845
Ethics committee country [1] 293621 0
Australia
Date submitted for ethics approval [1] 293621 0
24/03/2017
Approval date [1] 293621 0
26/07/2017
Ethics approval number [1] 293621 0
HRE2017-0490

Summary
Brief summary
Obesity significantly increases the risk of developing metabolic syndrome (MS), which is associated with increased cardiovascular morbidity/mortality. Presently, there is fierce debate surrounding the effects of the A1 beta-casein protein variant (A1) in bovine milk compared to the progenitor A2 variant (A2) with respect to their relative impact on MS risk factors. Most milk and milk products available commercially in Australia contain the A1 protein from dairy cows which carry the A1 gene. The A1 variant in Australian dairy cattle is the result of a mutation from the A2 gene in European herds ~5,000 years ago. Alternatively, milk produced by cows specially selected and then bred to produce only the original A2 beta-casein type is also available in Australia, but it is a specialty milk brand. Ample evidence now suggests that A1 milk beta-casein can affect features of MS and so has important public health implications. Given the Australian Dietary Guidelines recommend 2.5-4 dairy serves/day, the effect of milk variety on MS warrants investigation. A1 and A2 protein have differences in bioactivity on digestion, due to the release of the 7-amino acid opioid peptide beta-casomorphin-7 (BCM-7), from the digestion of A1 but not A2. In vitro and animal studies have demonstrated that BCM-7 oxidises low density lipoprotein (LDL)-cholesterol and increases levels of the inflammatory marker myeloperoxidase, both of which are implicated in the development of heart disease. A1 beta-casein and BCM-7 also stimulate inflammatory markers and so may contribute to the overall inflammatory milieu in MS. We have also shown in our recent randomised cross-over study that A1 milk stimulates differences in gastrointestinal inflammatory responses compared to A2 milk.

The aim of the current proposed project is to investigate the difference between A1 and A2 beta-casein protein containing milk on cardiovascular and metabolic risk factors in overweight/obese individuals. Simple and affordable nutrition interventions that can positively affect modifiable risk factors for heart disease and T2D in Australian adults are needed. If the predicted differences between A1 and A2 beta-casein containing milk on cardiometabolic risk outcomes are found, it will have important ramification for public health and the prevention of chronic illness like cardiovascular disease. Dairy farmers would be advised to choose A2 semen for their dairy breeding programs to change to the A2 milk type for Australian consumers.

We hypothesise that A1, but not A2 beta-casein containing milk, will correspond to shifts in cardiometabolic risk factors mediated via BCM-7 in blood. In contrast, we propose that A2 beta-casein containing milk will have a neutral, rather than beneficial, effect on metabolic syndrome factors. Thus, the hypothesis implies that A2 will do no harm, while the mutated A1 variant may increase the risk of chronic disease at a population health level.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 60706 0
A/Prof Sebely Pal
Address 60706 0
Curtin University
School of Public Health
Kent Street, Bentley, Perth
Western Australia 6102
Country 60706 0
Australia
Phone 60706 0
+61 8 9266 4755
Fax 60706 0
Email 60706 0
s.pal@curtin.edu.au
Contact person for public queries
Name 60707 0
Dr Suleen Ho
Address 60707 0
Curtin University
School of Public Health
Kent Street, Bentley, Perth
Western Australia 6102
Country 60707 0
Australia
Phone 60707 0
+61 422238198
Fax 60707 0
Email 60707 0
suleen.ho@curtin.edu.au
Contact person for scientific queries
Name 60708 0
Dr Suleen Ho
Address 60708 0
Curtin University
School of Public Health
Kent Street, Bentley, Perth
Western Australia 6102
Country 60708 0
Australia
Phone 60708 0
+61 422238198
Fax 60708 0
Email 60708 0
suleen.ho@curtin.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
IPD availability was not discussed during planning for this study.
What supporting documents are/will be available?
No other documents available
Summary results
No Results