Glycemic index of single and mixed meal foods among common Japanese foods with white rice as a reference food

Objective: The objectives were to examine the feasibility of using white rice as a reference food in the study of glycemic index (GI) and to examine the GI values of both single and mixed meal foods among rice species, processed rice products, beans, and dairy products. Design: Subjects were served with 50 g carbohydrate content of white rice at least two times (maximum three times) and test food once after separate overnight fasts. Capillary blood glucose measurements were carried out before and during 120 min after each food load. Setting: The study was carried out in an outpatient setting. Subjects: A total of 58 (38 females and 20 males) nondiseased subjects, mean aged 37 y and mean BMI 22 kg/m(2) were included. Result: The correlation between incremental area under curve of white rice and glucose was r = 0.853 (n = 10, P<0.0001) and white rice was considered suitable to be used as a reference food. Among mixed meal foods, the combination of carbohydrate foods with vinegar, dairy products, and bean products significantly decreased the GI value of white rice of 20-40%. The reduction of GI occurred whether the foods were taken together, before or after rice intake. GI of noodles such as udon, soba, and spaghetti showed low GI values. Conclusion: White rice could be used as a reference food in determining GI values of foods. A total of 32 single and mixed meal Japanese common food products were examined for their GI values.