Estimation of glycemic and insulinemic responses to short-grain rice (Japonica) and a short-grain rice-mixed meal in healthy young subjects.

We estimated glycemic and insulinemic responses to short-grain rice (Japonica) and a short-grain rice-mixed meal (i.e. short-grain rice and other ingredients) in three healthy male, and five healthy female subjects aged 22-31 years. A 50 g carbohydrate portion of dry rice was used in this study to estimate the glycemic index (GI) of short-grain rice (Experiment 1). The GI of short-grain rice was 68 (white bread = 100). In Eperiment 2, the subjects took three mixed meals (rice-, bread- and cornflakes-mixed) containing 60 g available carbohydrate, 25-29 g fat, 18-22 g protein, 2331-2486 kJ energy, and 67-123 meal GI in order to detemine whether both the amount and source of carbohydrate consumed determined postprandial glycemic and insulinemic responses of mixed meals. Glycemic response after the rice-mixed meal was significantly lower (p<0.05) than that after the cereal-mixed meal. The predicted glycemic and insulinemic responses, based on GI and the amount of carbohydrate, were related to the observed mean plasma glucose responses. These results suggest that short-grain rice (Japonica) grown in Japan should not be classified as a high GI food and that, in a mixed meal, it is a lower glycemic and insulinemic responder compared with bread or cereal mixed meals. Moreover, both the amount and source of carbohydrate consumed determine the glycemic and insulinemic responses after different mixed meals with variable GI.