The role of digestive factors in determining glycemic response in a multiethnic Asian population

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.

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.

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).

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.