Purpose: 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).
Conclusion: 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.
Keywords: AMY1; Gastric emptying; Glycemic response; Mastication; Salivary amylase.