Glycemic Index of Single and Mixed Meal Foods Among Common Japanese Foods with White Rice As a Reference Food
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European Journal of Clinical Nutrition (2003) 57, 743–752 & 2003 Nature Publishing Group All rights reserved 0954-3007/03 $25.00 www.nature.com/ejcn ORIGINAL COMMUNICATION Glycemic index of single and mixed meal foods among common Japanese foods with white rice as a reference food M Sugiyama1*, AC Tang2, Y Wakaki3 and W Koyama3 1National Institute of Health and Nutrition, Japan; 2Department of Health Promotion Sciences, School of Health Science and Nursing, Faculty of Medicine, The Tokyo University, Japan; and 3Kumamoto Health Management Center, The Japanese Red Cross Company, Japan 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/m2 were included. Result: The correlation between incremental area under curve of white rice and glucose was r ¼ 0.853 (n ¼ 10, Po0.0001) 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. European Journal of Clinical Nutrition (2003) 57, 743–752. doi:10.1038/sj.ejcn.1601606 Keywords: glycemic index; rice; bean; dairy; vinegar; Japanese food Introduction Brand Miller, 1995). Among published literature, most Jenkins (Jenkins et al, 1981) introduced the glycemic index studies were based in Western cultures and had used either (GI) in 1981 by comparing the postprandial blood glucose white bread or glucose as the reference foods. For most Asian incremental area under curve (IAUC) of different carbohy- population who consume white rice as a staple food, rice is drate foods. Since the introduction of the GI, numerous more readily available and is considered more palatable. For studies were conducted to test the GI of different foods and routine use, white rice used as a reference food would be an International GI Table was published (Foster-Powell & more convenient in these countries when compared to white bread. Therefore, it is necessary to consider the use of white rice as a reference food. In addition, studies conducted *Correspondence: M Sugiyama, Division of Applied Nutrition, Laboratory among Japanese population with the internationally of Nutrition Care and Management, 1-23-1, Toyama, Shinjuku-ku, Tokyo 162-8636, Japan. adopted GI evaluation method have not been reported. As E-mail: [email protected] a result, limited items published in the literature can be Guarantor: M. Sugiyama. applied as common Japanese foods. Prior to the utilization Contributors: M Sugiyama provided the concept and design of the of the GI concept in Japanese research and clinical setting, it study. AC Tang carried out the literature research, data analyses and prepared the report. YW was responsible for data acquisition and is considered necessary to test the GI of commonly analyses. WK was also responsible for the data acquisition. consumed Japanese foods among the local population with GI of single and mixed Japanese meal foods M Sugiyama et al 744 white rice as a reference. The objectives of the current study Study protocol were to examine the feasibility of using white rice as a The experiment was based on the method by Wolever reference food and to test the GI of some common Japanese (Wolever et al, 1991). Groups of 9–11 subjects were derived food. from the total pool of 58 subjects to test for one food. All subjects took 50 g carbohydrate load of reference food (white rice) at least two times (maximum three times) and test food Method once on random days. A subject who took more than one test food had at least 2 days of wash-out period in between Subject food testing. Subjects started fasting from 09:00 on the A total of 58 healthy subjects (38 females and 20 males) who previous evening before examination. Meals were given to self-reported that they were not diagnosed with glucose the subjects from 07:00 to 09:00 on random days. Foods were intolerance or diabetes (based on their blood glucose consumed within 15 min. The subjects carried out self- and HbA examinations from the past 1 year) were 1c monitoring blood glucose measurement seven times in total: included. The demographic characteristics of the subjects at fast, and at 15, 30, 45, 60, 90, and 120 min after load. are shown in Table 1. These subjects had an average age of Capillary blood glucose measurement was performed using 37710 and BMI 2272.7 kg/m2 (mean7s.d.). In all 25 self-administered blood measuring device (Glutestase, Sanwa subjects had family history of diabetes, 11 subjects took Chemical Research Institute Co. Inc.). The reliability of the medication or supplements not related to glucose metabo- device was tested in another occasion by measuring the same lism. Informed consent was obtained from each of the blood sample for 30 times and the coefficient of variation subjects according to the requirements set by the ethics (CV) obtained was below 2.9. The correlation coefftcient of committee of the Japanese Red Cross Company, Kumamoto blood glucose value measured with self-administered blood Health Management Center, which conformed to the measuring device and the value measured using the glucose Helsinki Declaration. automatic analysis device (The First Co. Inc. Kyoto Science GA-1 140) was r ¼ 0.997 (n ¼ 62). Reference food The reference food was the aseptic packed Satou Rice, which was labeled to contain 34 g of carbohydrate per 100 g of rice. Calculation of the GI Each portion of the cooked rice weighed 147 g and contained The GI was defined as follows (Wolever, 1990): 50 g of carbohydrate value. Incremental area under blood glucose response curve ðIAUCÞfor a food GI ¼ Â 100 Corresponding area after equicarbohydrate Test food portion of a reference food Test foods were chosen from common Japanese processed rice products, beans, and dairy foods. A total of 32 items were IAUC of each test food and mean IAUC for the initial two tested for their GI based on white rice as the reference food. reference foods were calculated for each person. When the Each test food contained 50 g of carbohydrate. In mixed percentage change of the initial two reference foods IAUC meals or combination meals, the total nutrition value was more than 25%, the subject took reference food the third summed up to approximately 50 g carbohydrate. For exam- time and mean IAUC of the closest two values was used as ple, for white rice and yogurt, 132 g of white rice (44.9 g of the reference. On the other hand, if the per cent change of carbohydrate) and 100 g of yogurt (5.3 g carbohydrate) were the two closest IAUC exceeded 25%, the subject would be given as one test food item. The reference food, test foods, excluded from the analysis. Mean GI and s.d. of each test nutrition component, and methods of offering foods are food was obtained from the remaining subjects in the group. shown in Table 2. Subjects who had GI exceeding 2s.d. were also excluded from Table 1 Subject characteristics Total (n=58) Male (n=20) Female (n=38) Age (y) 37710 (22–66) 40711 (27–66) 3579 (22–53) BMI (kg/m2)2272.7 (17.1–28.4) 23.573.0 (18.5–28.4) 21.372.2 (17.1–27.1) Family diabetes history positive 25 4 21 Currently on Medication 11 2 9 Traditional medicine 4 1 3 Hormonal medication 3 1 2 Vitamin 3 F 3 Calcium supplement 1 F 1 European Journal of Clinical Nutrition Table 2 Nutrient component, amount, and method of preparation for the common Japanese foods used Nutrition Value of Food Weight per Carbo- Produced by portion hydrate Energy Protein Fat Sodium Name of Food (Japanese Name) Ingredient and Food Form (Company Name) (g) (g) (kcal) (g) (g) (mg) Method of Preparationa White rice-reference food Aseptic packed white rice Satou Co. Ltd 147.0 50.2 223.0 3.5 0.9 4.4 Sprinkle algae on rice and warm (beihan) Dried sea algae Mishima Shokuhin 1.0 0.2 1.0 0.1 0.0 210.0 Serve in form of rice ball (onigiri) Dried sea algae (shiso) Total 50.4 224.0 3.6 0.9 214.4 1. Rice gruel Aseptic packed rice gruel Satou Co. Ltd 658.0 50.2 244.5 5.4 1.3 223.2 Mix dried algae in rice gruel and warm (okayu) Mishima Shokuhin 1.0 Serve with drink 2. Salted rice ball Aseptic packed white rice Satou Co. Ltd 147.0 50.0 222.0 3.4 0.9 Warm rice and sprinkle with salt (shiomusubi) Salt 3–5 1974.4–1954.4 Serve with drink 3.