Glycaemic index of parboiled rice depends on the severity of processing: study in type 2 diabetic subjects

Beneficial glycaemic effects of high-amylose barley bread compared to wheat bread in type 2 diabetes

BACKGROUND

Cereals foods with a high content of dietary fibres or amylose have potential to lower postprandial glucose levels. Optimisation of cereal foods may improve management of type 2 diabetes (T2D).

METHODS

We investigated the impact on 4 h postprandial glucose responses given as incremental area under curve (iAUC) of bread made of either 50% RNAi-based (genetically modified) amylose-only barley flour (AmOn) (and 50% wheat flour), 50% hulless barley flour (and 50% wheat flour) or 75% hulless barley (and 25% wheat flour) in subjects with T2D compared with 100% wheat flour bread.

DESIGN

Twenty adults with T2D were randomly allocated to one of four breads at four separate visits. We measured fasting and 4 h postprandial responses of glucose, insulin, glucagon, triacylglycerol (TG), free fatty acids (FFA), glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP). Mixed model ANOVA was used to examine the differences.

RESULTS

Bread made from 50% AmOn lowered the 4 h postprandial glucose by 34%, 27%, 23% (P < 0.05) compared with 100% wheat, 50% or 75% hulless barley, respectively. Bread made from 75% hulless barley reduced the postprandial glucose response (iAUC) by 11% (P < 0.05) compared to 100% wheat bread. Postprandial insulin responses (iAUC) were reduced for 50% AmOn compared with 100% wheat and 50% hulless barley and for 75% hulless compared to 50% hulless barley bread (P < 0.05). 4 h postprandial glucagon (tAUC) did not differ between the four bread types (P > 0.05). Lower postprandial GIP (iAUC) was observed after all barley breads compared to 100% wheat (P < 0.05), whereas no difference was seen in postprandial GLP-1. Postprandial TG and FFA (tAUC) were difficult to judge due to differences in fasting values.

CONCLUSIONS

Bread made by replacing wheat flour with either 50% high-amylose or 75% hulless barley flour lowered postprandial glucose responses compared to 100% wheat bread indicating a beneficial impact on glucose regulation in T2D subjects. This trial was registered at clinicaltrials.gov as NCT04646746.

Endosperm structure and Glycemic Index of Japonica Italian rice varieties

Introduction

Given that rice serves as a crucial staple food for a significant portion of the global population and with the increasing number of individuals being diagnosed with diabetes, a primary objective in genetic improvement is to identify and cultivate low Glycemic Index (GI) varieties. This must be done while ensuring the preservation of grain quality.

Methods

25 Italian rice genotypes were characterized calculating their GI "in vivo" and, together with other 29 Italian and non-Italian genotypes they were studied to evaluate the grain inner structure through Field Emission Scanning Electron Microscopy (FESEM) technique. Using an ad-hoc developed algorithm, morphological features were extracted from the FESEM images, to be then inspected by means of multivariate data analysis methods.

Results and Discussion

Large variability was observed in GI values (49 to 92 with respect to glucose), as well as in endosperm morphological features. According to the percentage of porosity is possible to distinguish approximately among rice varieties having a crystalline grain (< 1.7%), those intended for the preparation of risotto (> 5%), and a third group having intermediate characteristics. Waxy rice varieties were not united by a certain porosity level, but they shared a low starch granules eccentricity. With reference to morphological features, rice varieties with low GI (<55) seem to be characterized by large starch granules and low porosity values. Our data testify the wide variability of Italian rice cultivation giving interesting information for future breeding programs, finding that the structure of the endosperm can be regarded as a specific characteristic of each variety.

A comparison of the effects of resistant starch types on glycemic response in individuals with type 2 diabetes or prediabetes: A systematic review and meta-analysis

Background

Type 2 diabetes (T2D) diagnoses are predicted to reach 643 million by 2030, increasing incidences of cardiovascular disease and other comorbidities. Rapidly digestible starch elevates postprandial glycemia and impinges glycemic homeostasis, elevating the risk of developing T2D. Starch can escape digestion by endogenous enzymes in the small intestine when protected by intact plant cell walls (resistant starch type 1), when there is a high concentration of amylose (resistant starch type 2) and when the molecule undergoes retrogradation (resistant starch type 3) or chemical modification (resistant starch type 4). Dietary interventions using resistant starch may improve glucose metabolism and insulin sensitivity. However, few studies have explored the differential effects of resistant starch type. This systematic review and meta-analysis aims to compare the effects of the resistant starch from intact plant cell structures (resistant starch type 1) and resistant starch from modified starch molecules (resistant starch types 2-5) on fasting and postprandial glycemia in subjects with T2D and prediabetes.

Methods

Databases (PubMed, SCOPUS, Ovid MEDLINE, Cochrane, and Web of Science) were systematically searched for randomized controlled trials. Standard mean difference (SMD) with 95% confidence intervals (CI) were determined using random-effects models. Sub-group analyses were conducted between subjects with T2D versus prediabetes and types of resistant starch.

Results

The search identified 36 randomized controlled trials (n = 982), 31 of which could be included in the meta-analysis. Resistant starch type 1 and type 2 lowered acute postprandial blood glucose [SMD (95% CI) = -0.54 (-1.0, -0.07)] and [-0.96 (-1.61, -0.31)]. Resistant starch type 2 improved acute postprandial insulin response [-0.71 (-1.31, -0.11)]. In chronic studies, resistant starch type 1 and 2 lowered postprandial glucose [-0.38 (-0.73, -0.02), -0.29 (-0.53, -0.04), respectively] and resistant starch type 2 intake improved fasting glucose [-0.39 (-0.66, -0.13)] and insulin [-0.40 (-0.60, -0.21)].

Conclusion

Resistant starch types 1 and 2 may influence glucose homeostasis via discrete mechanisms, as they appear to influence glycemia differently. Further research into resistant starch types 3, 4, and 5 is required to elucidate their effect on glucose metabolism. The addition of resistant starch as a dietary intervention for those with T2D or prediabetes may prevent further deterioration of glycemic control.

Impact of Low-Temperature Storage on the Microstructure, Digestibility, and Absorption Capacity of Cooked Rice

This study examined the effects of low-temperature storage on the microstructural, absorptive, and digestive properties of cooked rice. Cooked rice was refrigerated and stored at 4 °C for 0.5, 1, 3, 5, and 7 days, as well as frozen and preserved at −20, −40, and −80 °C for 0.5, 1, 3, 5, 7, 14, 21, and 28 days. The results indicated that the stored rice samples generally exhibited a higher absorption capacity for oil, cholesterol, and glucose than the freshly cooked rice. In addition, after storage, the digestibility of the cooked rice declined, namely, the rapidly digestible starch (RDS) content and estimated glycemic index (eGI) decreased, whereas the slowly digestible starch (SDS) and resistant starch (RS) content increased. Moreover, the increment of the storage temperatures or the extension of storage periods led to a lower amylolysis efficiency. Scanning electron microscopy (SEM) analysis indicated that storage temperature and duration could effectively modify the micromorphology of the stored rice samples and their digestion. Moreover, microstructural differences after storage and during simulated intestinal digestion could be correlated to the variations in the absorption capacity and digestibility. The findings from this study will be useful in providing alternative storage procedures to prepare rice products with improved nutritional qualities and functional properties.

'Old Is Gold': How Traditional Indian Dietary Practices Can Support Pediatric Diabetes Management

Nutrition is crucial for maintaining normal growth, development, and glycemic control in young people with diabetes (PwD). Undue restrictions cause nutrient deficiencies as well as poor adherence to meal plans. Widespread availability of low-cost, ultra-processed, and hyperpalatable food is further damaging. Most families struggle to find ways to provide nutritious, yet attractive, food with a low glycemic index (GI). India is one of the oldest continuous civilizations with a rich and diverse cultural and culinary heritage. Traditional dietary practices, including the centuries-old 'Thali' (meaning plate) concept, emphasize combinations (grains, lentils, vegetables, dairy, spices, prebiotics and probiotics, and fats) of local, seasonal, and predominantly plant-based ingredients. These practices ensure that all of the necessary food groups are provided and fit well with current evidence-based recommendations, including the International Society for Pediatric and Adolescent Diabetes (ISPAD) 2018 Guidelines. Techniques for the preparation, cooking, and preservation of food further impact the GI and nutrient availability. These practices benefit nutrient density, diet diversity, and palatability and thus improve adherence to meal plans and glycemic control. This narrative review describes the ancient wisdom, food composition, and culinary practices from across India which are still valuable today. These may be of benefit worldwide to improve glycemic control as well as quality of life, especially in PwD.

A perspective on the benefits of consumption of parboiled rice over brown rice for glycaemic control

PURPOSE

Rice is a staple food for over 3.5 billion people worldwide. The nutritional content of rice varies with different post-harvest processing techniques. Major varieties include brown rice (BR), white rice (WR) and parboiled rice (PBR). While consumption of BR is advocated due to its higher nutritional content compared to other varieties, some studies have indicated lower post-prandial blood glucose (PPBG) levels when PBR is consumed. This apparent benefit of PBR consumption is not well publicised and no commentaries on underlying mechanisms are available in literature.

METHODS

In this review, we looked into differential nutrient content of PBR, as compared to BR and WR, and tried to understand how their consumption could be associated with glycaemic control. Various roles played by these nutrients in mechanisms of insulin secretion, insulin resistance, nutrient absorption and T2DM-associated inflammation were reviewed from literature-based evidence.

RESULTS

We report differential nutritional factors in PBR, with respect to BR (and WR), such as higher calcium and selenium content, lower phytic acids, and enriched vitamin B6 which might aid PBR's ability to provide better glycaemic control than BR.

CONCLUSION

Our interpretation of reviewed literature leads us to suggest the possible benefits of PBR consumption in glycaemic control and its inclusion as the preferred rice variant in diets of T2DM patients and at-risk individuals.

Impact of processing techniques on the glycemic index of rice

Rice is an important starchy staple food and generally, rice varieties are known to have a higher glycemic index (GI). Over the years, the significance of GI on human health is being better understood and is known to be associated with several lifestyle disorders. Apart from the intrinsic characteristics of rice, different food processing techniques are known to have implications on the GI of rice. This work details the effect of domestic and industrial-level processing techniques on the GI of rice by providing an understanding of the resulting physicochemical changes. An attempt has been made to relate the process-dependent digestion behavior, which in turn reflects on the GI. The role of food constituents is elaborated and the various in vitro and in vivo approaches that have been used to determine the GI of foods are summarized. Considering the broader perspective, the effect of cooking methods and additives is explained. Given the significance of the cereal grain, this work concludes with the challenges and key thrust areas for future research.

Gamma radiation application to rice: Reduced glycemic index in relation to modified carbohydrate observed in FTIR spectra

This study was conducted with a popular, low price Bangladesh rice variety BRRI Dhan 29 with a view to possible carbohydrate modification targeting lower glycemic index using gamma radiation application. Irradiation process (5 and 10 ​kGy ​at a dose rate of 9.74kGy/h) altered amylose content, amylose/amylopectin ratio, swelling power, and solubility index. FTIR spectroscopy confirmed the changed molecular structures due to radiation application. Treatment with a dose of 5 and 10kGy caused increased amylose and amylose/amylopectin ratio significantly (p ​< ​0.02). The highest amylose content was found in 10 ​kGy irradiated rice (30.20%) compared to unirradiated one (17.27%). Gamma radiation caused decreased swelling and increased water solubility in rice powder. These features of carbohydrate amendment in irradiated rice lead to reduced glycemic index as investigated with the in vivo experiments. Therefore, this study suggests gamma-irradiated rice (10kGy) is beneficial for diabetic subjects keeping lower blood glucose levels.

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Radiation processing of rice significantly enhanced amylose content

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FTIR spectrum confirmed the molecular rearrangement in irradiated rice

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Rice treated with gamma radiation at a 10kGy lowered Glycemic index significantly (p ​< ​0.02).

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Gamma irradiated rice having higher amylose content could be recommended for diabetic subjects.

Retention of Zn, Fe and phytic acid in parboiled biofortified and non-biofortified rice

Biofortified rice with high Zn concentration could reduce Zn deficiency in South Asia. This population frequently parboils rice. True retention (TR) of Zn, Fe and phytic acid after parboiling and milling was evaluated in biofortified and non-biofortified rice. TR in milled non-parboiled rice was 63.8-89.6% for Zn, 21.1-44.5% for Fe and 16.4-40.3% for phytic acid, whereas in milled parboiled rice TR was 49.8-72.2% for Zn, 23.4-36.7% for Fe and 22.0-33.3% for phytic acid. Milled parboiled rice resulted in lower Zn TR compared to milled non-parboiled. These results suggest that Zn moves from the inner endosperm towards the outer layers during parboiling, regardless of initial Zn concentration, consequently, once milled, the potential impact of Zn intake on Zn deficiency from parboiled rice is less than non-parboiled rice. Despite Zn losses during processing, biofortified rice could provide over 50% of the Zn EAR for children.

Finger millet porridges subjected to different processing conditions showed low glycemic index and variable efficacy on plasma antioxidant capacity of healthy adults

Abstract

Finger millet porridges (FMP), rich in nutrient and non-nutrient compounds have been used in the traditional food cultures in Asia. The aims of the study were to determine the effect of different processing conditions of finger millet grains on glycemic response, phenolic content and the antioxidant activities of FMP and to determine the short term and long term efficacy of its consumption on plasma antioxidant levels of healthy adults. Twelve types of FMP were prepared combining different processing conditions. Phenolic content of porridges as well as antioxidant activities were determined. The glycemic index (GI) and glycemic load (GL) values of FMP were also evaluated. The long term efficacy of FMP consumption on plasma glucose (PG), total cholesterol (TC) levels and plasma antioxidant capacity (PAC) of 18 subjects were investigated using a 24 weeks randomized cross-over study. The short term efficacy of porridge consumption on AC was determined. PAC was measured by trolox equivalent antioxidant capacity (TEAC) and ferric ion reducing antioxidant power (FRAP). All FMP exhibited low GI values (< 55) except the raw roasted flour which showed high and medium GI values for both particle sizes used. Parboiling of finger millet grains with 15 min steaming produced FMP with low glycemic response and possessed high PAC. Compared to baseline, PAC measured using FRAP and TEAC assays increased after 8 weeks consumption of porridge though significant changes were not observed for PG and TC levels. Furthermore, PAC was increased by 23 and 14% after 2 h of porridge consumption as measured by TEAC and FRAP, respectively. FMP consumption increased the plasma total antioxidant capacity of healthy adults. Further research on examining the potential of FMP on improving the antioxidant capacity in patients with diabetes is warranted.

Graphical abstract

Method of Food Preparation Influences Blood Glucose Response to a High-Carbohydrate Meal: A Randomised Cross-over Trial

The aim of this study was to establish the blood glucose response to different cooking methods of pasta. Participants consumed three identical meals in a random order that were freshly cooked (hot), cooled and reheated. Blood glucose concentrations were assessed before, and every 15 min after ingestion of each meal for 120 min. There was a significant interaction between temperature and time (F ( 8.46 - 372.34 ) = 2.75, p = 0.005), with the reheated (90 min) condition returning to baseline faster than both cold (120 min) and hot conditions. Blood glucose area under the curve (AUC) was significantly lower in the reheated (703 ± 56 mmol·L-1·min-1) than the hot condition (735 ± 77 mmol·L-1·min-1, t ( 92 ) = -3.36, pbonferroni = 0.003), with no significant difference with the cold condition (722 ± 62 mmol·L-1·min-1). To our knowledge, the current study is the first to show that reheating pasta causes changes in post-prandial glucose response, with a quicker return to fasting levels in both the reheated and cooled conditions than the hot condition. The mechanisms behind the changes in post-prandial blood glucose seen in this study are most likely related to changes in starch structure and how these changes influence glycaemic response.

Studies on in vitro bioavailability and starch hydrolysis in zinc fortified ready-to-eat parboiled rice (komal chawal)

Zinc fortified parboiled rice (komal chawal) was produced from a low amylose variety of rice by applying 'brown rice parboiling' method. In addition to the effect of milling on fortification, the effectiveness of fortification upon the amount of bioaccessible (in vitro digest) and bioavailable (cellular uptake) form of Zn was tested. The effect on glycaemic index was also assessed by employing an in vitro starch hydrolysis assay. The bioaccessible form of Zn in the unmilled fortified rice were ranged in between 4.24 and 11.07 mg/100 g, which was significantly higher (p < 0.05) than the milled and unfortified parboiled rice. Similarly, the % absorption of bioavailable Zn was negligible in the unfortified parboiled rice as compared to the fortified rice (14.5-24.5%). The estimated GI of fortified parboiled rice samples was in the range of 50.97-59.79, which was lower than the unfortified parboiled rice (58.80-62.53) and raw rice (78.71-84.64). The results thus demonstrated that Zn fortified komal chawal can be a novel and rapidly produced micronutrient enhanced ready-to-eat rice.

Appropriate parboiling steaming time at atmospheric pressure and variety to produce rice with weak digestive properties

Consumers with diabetes mellitus have shown interest in products with low postprandial glucose. To produce rice for this group of consumers, the effect of parboiling steaming time (0, 5, 15, 25, 35, and 45 min) and variety (NERICA1, NERICA7, WITA4, and IR841) on resistant, damaged starch fractions and glycemic response in rats was investigated. Resistant and damaged starch fractions were influenced by variety and steaming time but this was not the case for glycemic index. Nonparboiled NERICA7 and NERICA7 steamed for 25 min recorded the highest (10.07%) and lowest (2.49%) resistant starch fraction, respectively. Resistant starch correlated negatively with protein and sodium and positively with lipids. Damaged starch was high for WITA4 steamed for 45 min (26.80%) and low for nonparboiled NERICA1 (6.59%). Damaged starch correlated positively with lipid content and negatively with ash and total starch content. NERICA7 steamed for 35 min recorded the lowest postprandial glucose level 30 min after feeding (0.16 g/L), while WITA4 steamed for 15, 25, and 35 min and nonparboiled NERICA7 recorded higher levels (0.76, 0.91, 0.84, and 0.76 g/L, respectively). NERICA7 steamed for 35 min recorded both low glycemic and weak digestive properties because the glycemic index was lowest 120 min and increased steadily up to 180 min after feeding. We conclude that the digestive properties of rice depend both on the intrinsic properties of the variety and the parboiling steaming time.

Effect of Cold Storage and Reheating of Parboiled Rice on Postprandial Glycaemic Response, Satiety, Palatability and Chewed Particle Size Distribution

Background: Globally, hot cooked refined rice is consumed in large quantities and is a major contributor to dietary glycaemic load. This study aimed to compare the glycaemic potency of hot- and cold-stored parboiled rice to widely available medium-grain white rice. Method: Twenty-eight healthy volunteers participated in a three-treatment experiment where postprandial blood glucose was measured over 120 min after consumption of 140 g of rice. The three rice samples were freshly cooked medium-grain white rice, freshly cooked parboiled rice, and parboiled rice stored overnight at 4 °C. All rice was served warm at 65 °C. Chewing time was recorded. Results: incremental area under the curve (iAUC) of the control rice, freshly cooked medium-grain white rice, was the highest: 1.7-fold higher (1.2, 2.6) than reheated parboiled rice (p < 0.001) and 1.5-fold higher (1.0, 2.2) than freshly cooked parboiled rice (p = 0.001). No significant difference in postprandial glycaemic response was observed between freshly cooked and reheated parboiled rice samples (p = 0.445). Chewing time for 10 g cold-stored parboiled rice was 6 s (25%) longer and was considered more palatable, visually appealing and better tasting than freshly cooked medium-grain (all p < 0.05). Conclusions: For regular consumers of rice, reheating cooked rice after cold storage would lower the dietary glycaemic load and, in the long term, may reduce the risk for type 2 and gestational diabetes. More trials are needed to identify the significance.

Impact of postharvest drying conditions on in vitro starch digestibility and estimated glycemic index of cooked non-waxy long-grain rice (Oryza sativa L.)

BACKGROUND

Wet paddy needs to be dried to reduce its moisture content after harvesting. In this study, effects of postharvest drying condition on in vitro starch digestibility and estimated glycemic index of cooked rice (Oryza sativa L.) were investigated. Varying drying conditions, i.e. hot-air drying at 40, 65, 90 and 115 °C, and sun drying were applied to raw paddy. After husking and polishing, polished grains were cooked using an electric rice cooker. Cooked samples were analyzed for their moisture content and amount of resistant and total starch. Five samples in both intact grain and slurry were digested under simulated in vitro gastrointestinal digestion process. The in vitro starch digestion rate was measured and the hydrolysis index (HI) and estimated glycemic index (eGI) were calculated.

RESULTS

Cooked rice obtained from hot-air drying showed relatively lower HI and eGI than that obtained from sun-drying. Among samples from hot-air drying treatment, eGI of cooked rice decreased with increasing drying temperature, except for the drying temperature of 115 °C. As a result, cooked rice from the hot-air drying at 90 °C showed lowest eGI.

CONCLUSION

The results indicated that cooked rice digestibility was affected by postharvest drying conditions. © 2016 Society of Chemical Industry.

A systematic review of the influence of rice characteristics and processing methods on postprandial glycaemic and insulinaemic responses

Rice is an important staple food for more than half of the world's population. Especially in Asian countries, rice is a major contributor to dietary glycaemic load (GL). Sustained consumption of higher-GL diets has been implicated in the development of chronic diseases such as type 2 diabetes mellitus. Given that a reduction in postprandial glycaemic and insulinaemic responses is generally seen as a beneficial dietary change, it is useful to determine the variation in the range of postprandial glucose (PPG) and insulin (PPI) responses to rice and the primary intrinsic and processing factors known to affect such responses. Therefore, we identified relevant original research articles on glycaemic response to rice through a systematic search of the literature in Scopus, Medline and SciFinder databases up to July 2014. Based on a glucose reference value of 100, the observed glycaemic index values for rice varieties ranged from 48 to 93, while the insulinaemic index ranged from 39 to 95. There are three main factors that appear to explain most of the variation in glycaemic and insulinaemic responses to rice: (1) inherent starch characteristics (amylose:amylopectin ratio and rice cultivar); (2) post-harvest processing (particularly parboiling); (3) consumer processing (cooking, storage and reheating). The milling process shows a clear effect when compared at identical cooking times, with brown rice always producing a lower PPG and PPI response than white rice. However, at longer cooking times normally used for the preparation of brown rice, smaller and inconsistent differences are observed between brown and white rice.

Glycaemic and insulin responses, glycaemic index and insulinaemic index values of rice between three Asian ethnic groups

Asians exhibit larger glycaemic response (GR) and insulin response (IR) than Caucasians, predisposing to an increased risk of type 2 diabetes mellitus (T2DM). We aimed to determine the GR and IR as well as the glycaemic index (GI) and insulinaemic index (II) of two rice varieties among three ethnic groups in Singapore. A total of seventy-five healthy males (twenty-five Chinese, twenty-five Malay and twenty-five Asian-Indians) were served the available equivalent carbohydrate amounts (50 g) of test foods (Jasmine rice and Basmati rice) and a reference food (glucose) on separate occasions. Postprandial blood glucose and plasma insulin concentrations were measured at fasting ( -5 and 0 min) and at 15, 30, 45, 60, 90 and 120 min after food consumption. Using the trapezoidal rule, GR, IR, GI and II values were determined. The GR did not differ between ethnic groups for Jasmine rice and Basmati rice. The IR was consistently higher for Jasmine rice (P=0·002) and Basmati rice (P=0·002) among Asian-Indians, probably due to compensatory hyperinsulinaemia to maintain normoglycaemia. The GI and II of both rice varieties did not differ significantly between ethnicities. The overall mean GI for Jasmine rice and Basmati rice were 91 (sd 21) and 59 (sd 15), respectively. The overall mean II for Jasmine rice was 76 (sd 26) and for Basmati rice was 57 (sd 24). We conclude that the GI values presented for Jasmine rice and Basmati rice were applicable to all three ethnic groups in Singapore. Future studies should include deriving the II for greater clinical utility in the prevention and management of T2DM.

Advances to improve the eating and cooking qualities of rice by marker-assisted breeding

The eating and cooking qualities of rice are heavily emphasized in breeding programs because they determine market values and they are the appealing attributes sought by consumers. Conventional breeding has developed traditional varieties with improved eating and cooking qualities. Recently, intensive genetic studies have pinpointed the genes that control eating and cooking quality traits. Advances in genetic studies have developed molecular techniques, thereby allowing marker-assisted breeding (MAB) for improved eating and cooking qualities in rice. MAB has gained the attention of rice breeders for the advantages it can offer that conventional breeding cannot. There have been successful cases of using MAB to improve the eating and cooking qualities in rice over the years. Nevertheless, MAB should be applied cautiously given the intensive effort needed for genotyping. Perspectives from conventional breeding to marker-assisted breeding will be discussed in this review for the advancement of the eating and cooking qualities of fragrance, amylose content (AC), gel consistency (GC) and gelatinization temperature (GT) in rice. These four parameters are associated with eating and cooking qualities in rice. The genetic basis of these four parameters is also included in this review. MAB is another approach to rice variety improvement and development in addition to being an alternative to genetic engineering. The MAB approach shortens the varietal development time, and is therefore able to deliver improved rice varieties to farmers within a shorter period of time.

White rice consumption and risk of type 2 diabetes: meta-analysis and systematic review

OBJECTIVES

To summarise evidence on the association between white rice consumption and risk of type 2 diabetes and to quantify the potential dose-response relation.

DESIGN

Meta-analysis of prospective cohort studies.

DATA SOURCES

Searches of Medline and Embase databases for articles published up to January 2012 using keywords that included both rice intake and diabetes; further searches of references of included original studies.

STUDY SELECTION

Included studies were prospective cohort studies that reported risk estimates for type 2 diabetes by rice intake levels.

DATA SYNTHESIS

Relative risks were pooled using a random effects model; dose-response relations were evaluated using data from all rice intake categories in each study.

RESULTS

Four articles were identified that included seven distinct prospective cohort analyses in Asian and Western populations for this study. A total of 13,284 incident cases of type 2 diabetes were ascertained among 352,384 participants with follow-up periods ranging from 4 to 22 years. Asian (Chinese and Japanese) populations had much higher white rice consumption levels than did Western populations (average intake levels were three to four servings/day versus one to two servings/week). The pooled relative risk was 1.55 (95% confidence interval 1.20 to 2.01) comparing the highest with the lowest category of white rice intake in Asian populations, whereas the corresponding relative risk was 1.12 (0.94 to 1.33) in Western populations (P for interaction=0.038). In the total population, the dose-response meta-analysis indicated that for each serving per day increment of white rice intake, the relative risk of type 2 diabetes was 1.11 (1.08 to 1.14) (P for linear trend<0.001).

CONCLUSION

Higher consumption of white rice is associated with a significantly increased risk of type 2 diabetes, especially in Asian (Chinese and Japanese) populations.

Effect of rice parboiling on performance and metabolic responses in rats

This research is aimed at evaluating the effect of rice grains submitted to different processing (white or parboiling) on performance and biological responses in rat. Male Wistar rats were fed with diets containing white or parboiled rice grains of the cultivar IRGA 417. Wet and dry faecal production, fasting serum glucose concentration, serum total protein and organs' weights as liver, kidney and epididymal fat pads were not affected by processing. The animals in the treatment with parboiled rice showed higher body weight gain, feed intake, nitrogen excretion, serum triglycerides, uric acid levels and pancreas weight and lower feed conversion, faecal pH, albumin and serum HDL cholesterol, when compared with the treatment with white rice. The results obtained in this work allow the conclusion that structural change of rice components caused by parboiling results in variations in different essential body metabolic parameters, such as body weight gain, gastrointestinal function and glycaemic control.

Hypoglycaemic and hypolipidaemic effects of low GI and medium GL Indian diets in type 2 diabetics for a period of 4 weeks: a prospective study

This prospective study reports significant hypoglycaemic and hypolipidaemic effects in type 2 diabetic subjects who were provided the complete diet plan to be on low glycaemic index (GI) and low-medium glycaemic load (GL) Indian vegetarian snacks and mixed meals for 4 continuous weeks. Five millilitres of fasting blood sample drawn at weekly intervals for 4 weeks were analysed for blood glucose, HbA1c and lipid profile. Four weeks later mean blood glucose level of 173.6 mg% decreased to 137.8 mg%, HbA1c of 8% also decreased to 7.1% which reflected the blood glucose level during the study period and hence correlated well with the fall in blood glucose level. Triglyceride level of 244.5 mg% decreased to 164.7 mg% (p < 0.0001) and total cholesterol of 173.5 mg% decreased to 134.6 mg% (p < 0.0001). High-density lipoprotein cholesterol of 33 mg% increased to 39.8 mg% (p < 0.003), very low density lipoprotein (VLDL) cholesterol of 48.9 mg% decreased to 32.9 mg% (p < 0.0001) and low-density lipoprotein cholesterol of 90.1 mg% decreased to 64.3 (p < 0.009). This significant outcome can be improved further if compliance to low GI and low-to-medium GL diet is continued. This may achieve desired glycaemic control and that's limit oxidative stress.

Nutritional and sensory profile of two Indian rice varieties with different degrees of polishing

Traditional hand-pounded rice has been replaced today with highly polished white rice in the Asian Indian diets. The study aimed to evaluate the nutritional as well as the sensory differences between the brown (0% polish) and the rice milled to different degrees of polish (2.3, 4.4 and 8.0%). Bapatla and Uma (red pigmented) varieties in both raw and parboiled forms were used. The protein, fat, dietary fibre, γ-oryzanol, polyphenols, vitamin E, total antioxidant activity and free radical scavenging abilities of the brown rice decreased while the available carbohydrates increased with polishing. Sensory attributes of the cooked rice samples (whiteness, grain intactness, fluffiness, firmness, stickiness, chewiness and the cooked rice aroma) were evaluated by trained panelists. Scores for branny taste and chewiness decreased with polishing. On the whole, brown rice of both the varieties was readily accepted by the well-informed sensory trained panelists.

Glycaemic index of three Indian rice varieties

Three commonly consumed Indian rice varieties (Sona Masuri, Ponni and Surti Kolam) were tested for their glycaemic index (GI). Healthy volunteers were recruited and after an overnight fast were given a 50 g available carbohydrate portion of glucose (reference food) or different varieties of cooked rice (test foods) on separate occasions. The fasting as well as postprandial capillary blood glucose response was determined over 2 h, and the incremental area under the curve (IAUC) was calculated. The GI was calculated as the IAUC of the test food/IAUC of the reference food (glucose) × 100. The differences between the GI values for Sona Masuri (72.0 ± 4.5), Ponni (70.2 ± 3.6) and Surti Kolam (77.0 ± 4.0) rice varieties were non-significant (p = 0.606) and are all classified as high GI varieties of rice. There is an urgent need to study the GI of other commonly consumed rice varieties and to develop rice of a lower GI value.

A higher ratio of beans to white rice is associated with lower cardiometabolic risk factors in Costa Rican adults

BACKGROUND

A high intake of white rice is associated with the metabolic syndrome and type 2 diabetes. Costa Ricans follow a staple dietary pattern that includes white rice and beans, yet the combined role of these foods on cardiometabolic risk factors has not been studied.

OBJECTIVE

We aimed to determine the association between intake of white rice and beans and the metabolic syndrome and its components in Costa Rican adults (n = 1879) without diabetes.

DESIGN

Multivariate-adjusted means were calculated for components of the metabolic syndrome by daily servings of white rice and beans (<1, 1, or >1) and by the ratio of beans to white rice. The OR for the metabolic syndrome was calculated by substituting one serving of beans for one serving of white rice.

RESULTS

An increase in daily servings of white rice was positively associated with systolic blood pressure (BP), triglycerides, and fasting glucose and inversely associated with HDL cholesterol (P-trend <0.01 for all). An increase in servings of beans was inversely associated with diastolic BP (P = 0.049). Significant trends for higher HDL cholesterol and lower BP and triglycerides were observed for 1:3, 1:2, 1:1, and 2:1 ratios of beans to white rice. Substituting one serving of beans for one serving of white rice was associated with a 35% (95% CI: 15%, 50%) lower risk of the metabolic syndrome.

CONCLUSION

Increasing the ratio of beans to white rice, or limiting the intake of white rice by substituting beans, may lower cardiometabolic risk factors.