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

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

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.

Study Overview

• Status: Completed
• Conditions: Carbohydrate Intolerance
• Intervention / Treatment: Other: Glucose; Other: Glucose plus lactulose; Other: Hot Rice; Other: Cold Rice

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5C 2X3
      • Glycemic Index Laboratories

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 75 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Factorial Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

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

What is the study measuring?

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

Collaborators and Investigators

• Sponsor: University of Toronto
• Collaborators: Glycemic Index Laboratories, Inc
• Investigators: Principal Investigator: Thomas MS Wolever, MD, PhD, President, Medical Director

Publications and helpful links

General Publications

• Wolever TMS, El-Sohemy A, Ezatagha A, Zurbau A, Jenkins AL. Neither low salivary amylase activity, cooling cooked white rice, nor single nucleotide polymorphisms in starch-digesting enzymes reduce glycemic index or starch digestibility: a randomized, crossover trial in healthy adults. Am J Clin Nutr. 2021 Nov 8;114(5):1633-1645. doi: 10.1093/ajcn/nqab228.

Study record dates

Study Major Dates

• Study Start (Actual): August 29, 2018
• Primary Completion (Actual): December 21, 2018
• Study Completion (Actual): December 21, 2018

Study Registration Dates

• First Submitted: September 10, 2018
• First Submitted That Met QC Criteria: September 10, 2018
• First Posted (Actual): September 12, 2018

Study Record Updates

• Last Update Posted (Actual): January 11, 2019
• Last Update Submitted That Met QC Criteria: January 10, 2019
• Last Verified: January 1, 2019

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Gastrointestinal Agents; Lactulose
• Other Study ID Numbers: RIS protocol number 33593

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No