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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
What are the effects on carbohydrate digestion and absorption of variations in the salivary amylase gene in healthy adults?
Scientific title
Physiological significance of AMY1 gene copy number variation in healthy individuals after consumption of high carbohydrate meals
Secondary ID [1] 291335 0
Universal Trial Number (UTN)
Trial acronym
SAMY study
Linked study record

Health condition
Health condition(s) or problem(s) studied:
obesity 302320 0
diabetes 302321 0
Condition category
Condition code
Diet and Nutrition 301903 301903 0 0
Metabolic and Endocrine 302348 302348 0 0
Normal metabolism and endocrine development and function

Study type
Description of intervention(s) / exposure
We will compare the rate and extent of digestion of starchy meals and sugary meals in healthy adults. There will be a variable number of acute meal tests, dependent on the person's actual AMY1 gene copy number (minimum 4 sessions and maximum 20 sessions). Individuals with either low AMY1 copy number (5 or fewer copies of the AMY1 gene) or high AMY1 copy number (9 or more copies of the AMY1 gene) will complete up to the maximum 20 sessions (or until consent is withdrawn). Participants with either low or high AMY1 copy number will be randomly allocated to receive one treatment at each visit, including 2 control reference sessions (25 g or 50 g glucose in solution) and any combination of 25/50/75 g carbohydrate (containing starch, sugar or both starch and sugar), and any of the listed food types or a mixed meal. Carbohydrate foods tested include white bread, pasta, rice, breakfast cereals, potatoes, oats, fruit and dairy products. The mixed meals contain egg, toast and orange juice or rice with soy sauce. Individuals with 6 - 8 AMY1 gene copies will complete the minimum of 4 sessions ((2 control sessions containing glucose in solution and 2 test food sessions containing white bread, pasta, rice, potatoes, oats, fruit or dairy products (randomly allocated)). There will be washout period of at least one day between sessions.

Fingerprick blood and breath samples will be taken at regular intervals (15-60 mins) over for minimum of 2 hours and maximum of 8 hours. The participants will complete a questionnaire about feelings of fullness and gastrointestinal symptoms. All sessions will be conducted on the main campus of the University of Sydney. A qualified dietitian (APD accredited practising dietitian) will conduct all sessions.
Intervention code [1] 297366 0
Early detection / Screening
Comparator / control treatment
Each subject acts as their own control, ie. their postprandial responses are compared relative to their response to the control food (glucose in solution). A control reference food (25 or 50 g of glucose in solution) will be consumed by every participant on 2 occasions.
Control group

Primary outcome [1] 301336 0
Postprandial plasma glucose responses
Timepoint [1] 301336 0
Relative postprandial glucose concentration assessed as incremental area under curve over 120 mins (0, 15, 30, 45, 60 ,90, 120 min) to the test food versus the reference food.
Primary outcome [2] 301770 0
Postprandial plasma insulin responses
Timepoint [2] 301770 0
Relative postprandial insulin concentration assessed as incremental area under curve over 120 mins (0, 15, 30, 45, 60 ,90, 120 min) to the test food versus the reference food.
Primary outcome [3] 301771 0
Postprandial breath hydrogen and methane responses over 8 hours.
Timepoint [3] 301771 0
Breath hydrogen and methane concentration assessed as area under curve over 8 hours (0, 15, 30, 45, 60, 90, 120, 180, 240, 300, 360, 420, 480 min) to two starchy meals containing rice with and without a source of resistant starch (HiMaize).
Secondary outcome [1] 332316 0
Nutritional composition of usual diet, including proportion of energy as starch.
Timepoint [1] 332316 0
Diet assessed by a 3-day written food record at baseline.
Secondary outcome [2] 333811 0
Postprandial satiety (feeling of fullness) assessed over 120 mins
Timepoint [2] 333811 0
Satiety assessed at as incremental area under the curve (0, 15, 30, 45, 60, 90 and 120 mins)
Secondary outcome [3] 333812 0
Salivary amylase activity
Timepoint [3] 333812 0
Assessed in fasting state only or in the case of the breath studies at hourly intervals for 8 hours.

Key inclusion criteria
Healthy, non-smoker, good comprehension of English
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Smoking, food allergy or intolerance, diagnosed diabetes, taking medications known to influence glucose metabolism

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Not applicable
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Computer-generated randomisation to order of meals
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Unpaired and pair t tests to compare mean difference in 2 groups
Linear regression analysis to determine linear trends

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 295804 0
Name [1] 295804 0
The University of Sydney
Address [1] 295804 0
Faculty of Science
University of Sydney
NSW 2006
Country [1] 295804 0
Primary sponsor type
The University of Sydney
Faculty of Science
University of Sydney
NSW 2006
Secondary sponsor category [1] 294647 0
Name [1] 294647 0
Address [1] 294647 0
Country [1] 294647 0

Ethics approval
Ethics application status
Ethics committee name [1] 297094 0
Human Research Ethics Committee University of Sydney
Ethics committee address [1] 297094 0
The University of Sydney
NSW 2006
Ethics committee country [1] 297094 0
Date submitted for ethics approval [1] 297094 0
Approval date [1] 297094 0
Ethics approval number [1] 297094 0
Ethics committee name [2] 297180 0
Research Ethics and Governace Office, Sydney Local Health District
Ethics committee address [2] 297180 0
Research Ethics and Governance Office
Royal Prince Alfred Hospital
NSW 2050
Ethics committee country [2] 297180 0
Date submitted for ethics approval [2] 297180 0
Approval date [2] 297180 0
Ethics approval number [2] 297180 0

Brief summary
The aim of this study is to identify the variation of the salivary amylase (AMY1) gene copy number in the Australian population and to investigate the effect of AMY1 copy number on carbohydrate digestion, acute metabolic and satiety responses, and potential associations with obesity and diabetes risk.

This project will screen Australian adults for their number of copies of the AMY1 gene. This gene produces a protein, salivary amylase, which is secreted in the mouth and begins starch breakdown. Individuals with varying AMY1 copy numbers will be asked to perform a series of starch challenge tests during which they will consume different high carbohydrate foods. Fingerprick blood samples will be taken at regular intervals over 2 hours to measure their metabolic responses to starchy foods. To assess the efficiency of starch digestion, salivary amylase activity, breath hydrogen and methane responses, and postprandial glucose and insulin responses will also be assessed over an 8 hour period following the consumption of different high carbohydrate meals. Information on how AMY1 copy number influences carbohydrate metabolism and usual dietary intake may have important implications for the dietary management of diabetes and obesity and/or identify those at greater risk of developing these conditions.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 72958 0
Prof Jennie Brand-Miller
Address 72958 0
Charles Perkins Centre
Johns Hopkins Drive
The University of Sydney
NSW 2006
Country 72958 0
Phone 72958 0
+ 61 417 658 695
Fax 72958 0
Email 72958 0
Contact person for public queries
Name 72959 0
Dr Fiona Atkinson
Address 72959 0
Charles Perkins Centre
Johns Hopkins Drive
The University of Sydney
NSW 2006
Country 72959 0
Phone 72959 0
+61 02 9351 6018
Fax 72959 0
Email 72959 0
Contact person for scientific queries
Name 72960 0
Dr Fiona Atkinson
Address 72960 0
Charles Perkins Centre
Johns Hopkins Drive
University of Sydney
NSW 2006
Country 72960 0
Phone 72960 0
+61 02 9351 6018
Fax 72960 0
Email 72960 0

No data has been provided for results reporting
Summary results
Not applicable