To elucidate the effect of a typical Vietnamese diet including a high content of white rice on postprandial blood glucose levels, the present study was designed. Thirty healthy female subjects with a similar body mass index, 10 each in their twenties, forties and sixties, were recruited. Four meals with a similar protein energy percentage (13-15%) but different energy ratios of fat and carbohydrate (FC ratio) and vegetable contents were provided by cross-over design. Meal A was designed according to the commonly consumed diet in Vietnam. The FC ratio was 14 : 71 and 84 g of carbohydrate was from rice. Meal B contained carbohydrate in a lower ratio than meal A by fat replacement and its FC ratio was 30 : 57. Meal C was similar to meal A except lacking vegetables. The energy of meal A, B and C was about 2.1 MJ. Meal D was designed to match the amount of carbohydrate and fat within A and B, respectively. The FC ratio of meal D was 26 : 61 and the energy was about 2.4 MJ. Fasting blood glucose was measured before consumption of a test meal. Postprandial blood glucose was measured every 30 min for 2 h. Areas under the curve (AUC) were calculated to compare the glycemic response among the four test meals. There was no significant difference in AUC among the four test meals in the subjects in their twenties. In the subjects in their forties, the AUC of meal A tended to be lower than that of meal C (p=0.07). In the subjects in their sixties, the AUC of meal A was significantly higher than that of meal B (p<0.001). Glycemic responses showed a significant relationship with age (r=0.26, p<0.01); however, there was no association between glycemic responses and BMI (p=0.20). Dietary fat ratios were inversely associated with glycemic responses (r=−0.28, p<0.01). In conclusion, the diet with about 70% energy from carbohydrate which is commonly consumed by Vietnamese may increase glycemic response, especially in elderly people and dietary vegetables may be beneficial to prevent such an increase in glycemic response.
Journal of Nutritional Science and Vitaminology 53(3),247-252