https://imcjms.com/public Ibrahim Medical College Journal of Medical Science https://imcjms.com/public/registration/journal_full_text/109 Sat, 08 Oct 2016 14:37:18 +0000 Abstract Methods: Seventeen type 2 diabetic subjects ingested five test meals of 50g available carbohydrate as white bread, cooked rice with high (29%) and low amylose content (13%), undergoing different processing and gelatinization temperatures. The diets were taken in a random order after a 10h overnight fast with approximately 7 days interval as wash out period. Conclusions: In type 2 diabetic subjects the investigated rices were all low glycemic as compared to white bread, independent of parboiling and physico-chemical characteristics. The study showed that the amylose content, but not the gelatinization temperature, may be an useful criteria in selection of low GI rices irrespective of parboiling status. Address for Correspondence: Dr. Shahana Parvin, Associate Professor, Department of Biochemistry; Northern International Medical College; Plot #8A, Road # 7, Dhanmondi; Dhaka – 1205, Bangladesh, Phone: 880-2-9668018, 8621479 - 83; Ext – 228   Rice, the staple food, constituting up to 80% of the daily energy intake, is the main carbohydrate source of Bangladeshi population and is predominant in the daily diet for these people1. Diabetic subjects are especially prescribed starchy foods with low glycemic responses2. Wide variations have been observed in the glycemic responses to rice. Some studies have found a low glycemic response for rice compared to white bread3. In contrast, Miller found higher glycemic responses to rice than to white bread4. The aim of the study was to examine the relationship between parboiling and physico-chemical characteristics of different rice varieties and the impact on blood glucose and insulin responses in type 2 diabetic subjects. Materials and Methods Seventeen type 2 diabetic subjects (8 male, 9 female) were included in this study. The subjects were selected from the out-patients department of BIRDEM. Diabetes was diagnosed and classified by the WHO criteria5. Patients with acute or chronic complications of diabetes mellitus and those using insulin, oral contraceptives or steroids were excluded from the study. Pregnancy was also an exclusion criterion. All participants gave their written consent after being fully informed about the nature of the study. Methods Four varieties of rice and white bread as reference food, having 50g available carbohydrate were given to the subjects. The rice varieties (BR16, BR25 and BR32) were obtained from Bangladesh Rice Research Institute (BRRI), Gazipur, where they were grown, harvested, parboiled, husked and milled. White bread was baked in one batch, sliced and portioned. Each bread portion was kept frozen and removed from the freeze 45 mins before serving. The rice was boiled in excess water and cooked to its minimum cooking time to ensure the same degree of gelatinization of the starch. Physico-chemical characteristics of test food   All chemical analysis was determined in duplicates at the National Institute of Animal Science, Foulum, Denmark. Dry matter (DM) was determined by oven drying at 105ºC for 20h. Available carbohydrate was determined as total starch by an enzymatic colorimetric method8. Protein (N*6.25) was analyzed using a Kjell-Foss 16200 Autoanalyser and fat was determined after hydrolysis and diethyl ether extraction according to Stoldt9. Biochemical analysis   The incremental plasma glucose and insulin response areas were calculated geometrically according to Wolever and Jenkins10. Results were expressed as means ± SD. Data were analyzed by a two way analysis of variance (ANOVA) followed by paired t-tests of means if the ANOVA indicated significance. The limit of significance was set at p<0.05. Results     Variables Age (years, M±SD) BMI (M±SD) Waist-hip ratio (M±SD) Female : Male Rural : Urban Duration of diabetes (months- M±SD) Fasting plasma glucose (mmol/L, M±SD) Annual income (median-range) in US Dollars HbA1C (%, M±SD)       Non-parboiled and parboiled rice of the same variety did not show statistical difference in incremental glucose and insulin response areas (Table 3). This was also reflected in their GI values (50±7 for BR16pb and 52±7 for BR16np) (Table 3). Amylose content     Rice variety BR16pb BR32pb GT / Alkali spreading value 4 4 3 7 Equilibrium water content (%)* 11 26 28 28   Gel consistency: hard (<40 mm), medium (41-60 mm), soft (>61 mm); Length/breath ratio: long grain (³3.1), medium grain (2.1-3.0), short grain (£2.0) Table-3: Metabolic responses to test meals (n = 17 type 2 diabetic patients) WB BR16pb BR32pb 756±65a 391±69b 361±48b 100a 50 ± 7b 47 ± 4b 20184±1643 12811±1505 13011±1949 Results are expressed as mean ± SD. P<0.05 was taken as the level of significance. iAUC: Incremental area under cure; GI: glycemic index; WB: white bread. Means in the same row followed by different superscript letters are significantly different. Gelatinization Temperature (GT)   Rice is suitable for use as low glycemic diets in the dietary management of type 2 diabetic subjects. Interestingly it is widely believed particularly in Asia like Bangladesh that diabetic subjects should limit their rice intake due to a positive association between a high intake of rice and the risk of developing diabetes. As starch is the principal component of rice, the physicians and dieticians advise diabetics as well as cardiovascular patients with substantial restriction of this major carbohydrate source. To rationalize the advice, it is important to know their physicochemical properties and their biological responses. The substitution of calories and other nutrients may then be done on the basis of patient’s choice, socioeconomic capability and availability in the market. The low GI of rice may be due to a delayed enzymatic hydrolysis of the whole grains, a process that can be accelerated by grinding11. In contrast Miller et al. found high GI to a number of Australian rice varieties4. These discrepancies may be due to differences in the physico-chemical characteristics, processing and/or cooking time of the rice varieties. Differences in the cooking time may influence the degree of gelatinization of the rice starch and the glycemic responses12. In the present study, the minimum cooking time for the rice was estimated and applied, ensuring that ³90% of the rice kernels have full cooked centers. Thus, the low GI of rice in type 2 diabetic subjects found in the present study cannot be explained by the cooking time. The study found no effect of parboiling on plasma glucose and insulin responses as well as in the GI values. This is in accordance with the results of Miller, but in contrast to Casiragi4, 14. One explanation for the varying effects may be ascribed to the parboiling process used. In our study, a traditional parboiling process, adapted from BRRI, was applied. This method may be regarded as a relatively mild procedure compared to the parboiling process used in the industrial trade, e.g. pressure parboiling. The severity of parboiling has been shown to affect some of the physico-chemical properties of rice starch15. Panlasigui et al. suggested that GT might be a useful parameter to predict the variation in the metabolic responses observed for rices with similar amylose content12. From the study we found no differences in the plasma glucose and insulin responses in the study subjects after ingestion of parboiled rice with low and high GT. A number of reasons may explain this result. We cooked the rice samples to the estimated minimum cooking time. It is also possible that the parboiling process reduced a possible effect of GT on the glycemic and insulinemic responses. Finally, the two rice varieties varied in gel consistency, which may have acted as a confounding factor. Conclusions   1.  Choudhury OH. A review of literature on nutrition studies in Bangladesh. Dhaka: Bangladesh Institute of Development Studies, 1992. 3.  Jenkins DJA, Wolever TMS, Tailor RH, Barker H, Fielden H, Baldwin JM et al: Glycemic Index of foods: a physiological basis for carbohydrate exchange. Am J Clin Nutri 1981; 34: 362-366. 5.  WHO Study Group. Prevention of diabetes mellitus. WHO Technical Report Series no 844. World Health Organization, Geneva, 1994. 7.  Little RR, Hilder GB and Dawson EH. Differential effect of dilute alkali on 25 varieties of milled white rice. Cereal Chemists 1985;  35: 111-126. 9.  Stoldt W. Suggestions to standardize the determination of fat in foodstuffs. Fette, seifen, anstrichtsmitted 1952; 54: 206–207. 11.O’Dea K, Nestal PJ and Antonoff L. Physical factors influencing postprandial glucose and insulin responses to starch. Am J Clin Nutr 1980; 33: 760-765. 13.Kaplan NM. Hypertension and diabetes. In: Porte D Jr, Sherwin RS, editors. Ellenberg and Rifkin’s Diabetes Mellitus. 5th ed. Stamford Connecticut: Appleton and Lange 1996; 1097–1104. 15.Biswas SK and Juliano BO. Laboratory parboiling procedures and properties of parboiled rice from varieties differing in starch properties. Cereal Chemists 1988; 65: 417-423. 17.Sowbhagya CV, Ramesh BS and Ali SZ. Hydration, Swelling and solubility behavior of rice in relation to other physico-chemical properties. J Sci Food Agric 1994; 64: 1-7. 2026 Ibrahim Medical College. All rights reserved.