title: The role of digestive factors in determining glycemic response in a multiethnic Asian population.
abstract: OBJECTIVE
  There are wide inter-individual differences in glycemic response (GR). We aimed to examine key digestive parameters that influence inter-individual and ethnic differences in GR in healthy Asian individuals.
  
  
  METHODS
  Seventy-five healthy male subjects (25 Chinese, 25 Malays, and 25 Asian-Indians) were served equivalent available carbohydrate amounts (50 g) of jasmine rice (JR) and basmati rice (BR) on separate occasions. Postprandial blood glucose concentrations were measured at fasting (-5 and 0 min) and at 15- to 30-min interval over 180 min. Mastication parameters (number of chews per mouth and chewing time per mouthful), saliva α-amylase activity, AMY1 gene copy numbers and gastric emptying rate were measured to investigate their relationships with GR.
  
  
  RESULTS
  The GR for jasmine rice was significantly higher than for basmati rice (P < 0.001). The median number of AMY1 gene copies was 6, with a range of 2-15. There was a significant positive relationship between AMY1 copy number and α-amylase activity (P = 0.002). There were no significant ethnic differences in GR. For both rice varieties, the number of chews per mouthful was positively associated with the GR (JR, P = 0.011; BR, P = 0.005), while chewing time per mouthful showed a negative association (JR, P = 0.039; BR, P = 0.016). Ethnicity, salivary α-amylase activity, particle size distribution, gastric emptying rate and AMY1 gene copy numbers were not significant contributors to GR (P > 0.05).
  
  
  CONCLUSIONS
  Mastication parameters contribute significantly to GR. Eating slowly and having larger food boluses before swallowing (less chewing), both potentially modifiable, may be beneficial in glycemic control.
authors.affiliation: Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore. verena_tan@sics.a-star.edu.sg.|Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. verena_tan@sics.a-star.edu.sg.
authors.forename: Verena Ming Hui
authors.initials: VM
authors.lastname: Tan
authors.affiliation: Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Delicia Shu Qin
authors.initials: DS
authors.lastname: Ooi
authors.affiliation: Department of Diagnostic Imaging, National University Hospital, National University Health System, Singapore, Singapore.
authors.forename: Jeevesh
authors.initials: J
authors.lastname: Kapur
authors.affiliation: Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.
authors.forename: Ting
authors.initials: T
authors.lastname: Wu
authors.affiliation: Biostatistics Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Yiong Huak
authors.initials: YH
authors.lastname: Chan
authors.affiliation: Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.|Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Christiani Jeyakumar
authors.initials: CJ
authors.lastname: Henry
authors.affiliation: Clinical Nutrition Research Centre (CNRC), Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.|Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.|Division of Paediatric Endocrinology and Diabetes, Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, National University Health System, Singapore, Singapore.
authors.forename: Yung Seng
authors.initials: YS
authors.lastname: Lee
mesh_terms: D050154:Adiposity; D000328:Adult; D044466:Asian People; D001786:Blood Glucose / Q000378:metabolism*; D001794:Blood Pressure; D015992:Body Mass Index; D002681:China; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000032:analysis; D004063:Digestion / Q000208:ethnology*; D005746:Gastric Emptying / Q000235:genetics / Q000502:physiology; D018628:Gene Dosage; D038321:Glycemic Index; D006801:Humans; D007194:India; D016014:Linear Models; D008296:Malaysia; D008297:Male; D008409:Mastication; D012275:Oryza / Q000737:chemistry / Q000145:classification; D010316:Particle Size; D019518:Postprandial Period; D055291:Salivary alpha-Amylases / Q000235:genetics; D055105:Waist Circumference; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; C524788:AMY1A protein, human; D055291:Salivary alpha-Amylases
keywords: AMY1; Gastric emptying; Glycemic response; Mastication; Salivary amylase