Effect of Genetic Variation in Starch-digesting Enzymes on Digestibility and Glycemic Index of Cold and Hot Rice

Study Overview
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Brief Summary
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This study evaluates the effect of different methods of preparation (cooked and consumed hot vs cooked, cooled overnight and consumed cold) and variation in the activity of salivary amylase on the glycemic index and carbohydrate digestibility in healthy human subjects. The effect of genetic variation in small intestinal starch digesting enzymes on glycemic index and starch digestibility will also be assessed.

Official Title
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Effect of Genetic Variation in Starch-digesting Enzymes on Digestibility and Glycemic Index of Rice Prepared in Different Ways

Conditions
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Carbohydrate Intolerance

Intervention / Treatment
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* Other: Glucose
* Other: Glucose plus lactulose
* Other: Hot Rice
* Other: Cold Rice


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Males or non-pregnant females aged 18-75 years and in good health Eligible to receive income in Canada Have Ontario Health Insurance Plan or equivalent medical coverage. Previous donor of saliva using protocol reference number # 31093 or GIL-1670 (in which subject consents to measurement of salivary amylase activity and genetic variation in AMY1, SI and MGAM genes). Salivary amylase activity in the lowest tertile (<50 U/ml) or highest tertile (>105 U/ml) of salivary amylase activity of 40 subjects previously measured. Exclusion Criteria: known history of AIDS, hepatitis, diabetes or a heart condition Allergy to rice, canola oil or sesame oil. use of medications (including, but not limited to, insulin or other antidiabetic drugs, systemic steroids, antipsychotics, protease inhibitors, antivirals, immunosuppressive agents and drugs affecting gut motility or digestion) or with any condition which might, in the opinion of Dr. Wolever, the Medical Director or GI Labs, either: 1) make participation dangerous to the participant himself (or herself) or to others, or 2) affect the results. individuals who cannot or will not comply with the experimental procedures or do not follow the instructions of GI Labs staff related to the safe performance of the experimental procedures

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

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: Basic Science
Allocation: Non-Randomized
Intervention Model: Factorial Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Low Salivary Amylase Activity<br>Glucose Glucose plus lactulose Hot Rice Cold Rice | Other: Glucose<br>* 50g glucose dissolved in 250ml water<br>Other: Glucose plus lactulose<br>* 50g glucose plus 10g lactulose dissolved in 250ml water<br>Other: Hot Rice<br>* Freshly cooked polished rice containing 50g available carbohydrate (approximately 2/3 cup cooked rice) and consumed hot.<br>Other: Cold Rice<br>* Cooked polished rice containing 50g available carbohydrate (approximately 2/3 cup cooked rice) cooled overnight in a refrigerator and consumed cold.<br>|
| Other: High Salivary Amylase Activity<br>Glucose Glucose plus lactulose Hot Rice Cold Rice | Other: Glucose<br>* 50g glucose dissolved in 250ml water<br>Other: Glucose plus lactulose<br>* 50g glucose plus 10g lactulose dissolved in 250ml water<br>Other: Hot Rice<br>* Freshly cooked polished rice containing 50g available carbohydrate (approximately 2/3 cup cooked rice) and consumed hot.<br>Other: Cold Rice<br>* Cooked polished rice containing 50g available carbohydrate (approximately 2/3 cup cooked rice) cooled overnight in a refrigerator and consumed cold.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glycemic Index (GI) | For each subject, the incremental area under the glucose response curve over 2 hours (iAUC) after each rice test meal is expressed as a percentage of the mean iAUC elicited by the 2 glucose test meals. | 0-2 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Carbohydrate malabsorbed | For each test meal the sum of breath hydrogen concentrations from the lowest value over 0-3 hours to 6 hours (termed H). For each subject the amount of hydrogen per gram malabsorbed carbohydrate (H/g) is calculated as (GL-G)/10 where GL is H after the glucose plus lactose meal and G is H after the glucose meal. The amount of carbohydrate malabsorbed after the hot and cold rice meals, respectively, are HR/Hg and CR/Hg, where HR and Cr are H after the hot and cold rice meals. | 0-6 hours. | 
| Glycemic response | The incremental area under the blood glucose response curve | 0-2 hours | 
| Breath hydrogen response | Sum of breath hydrogen concentrations from the lowest in the first 3 hours to 6 hours. | 0-6 hours |