None listed
Conditions
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.
Interventions
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AMY1 copy number (9 or more copies of the AMY1 gene) will complete up to the maximum 20 sessions (or until consent is withdrawn).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 ei
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AMY1 copy number (9 or more copies of the AMY1 gene) will complete up to the maximum 20 sessions (or until consent is withdrawn).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.
Sponsors
The University of Sydney
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
Healthy, non-smoker, good comprehension of English
Exclusion criteria
Smoking, food allergy or intolerance, diagnosed diabetes, taking medications known to influence glucose metabolism
Outcome results
None listed