White rice, brown rice and the risk of type 2 diabetes: a systematic review and meta-analysis

Health and Economic Impacts of Increased Brown Rice Consumption on Type 2 Diabetes in Japan: A Simulation Study, 2019-2029

BACKGROUND/OBJECTIVES

Whole grain consumption is recognized as a key component of healthy diets, offering protection against non-communicable diseases, including type 2 diabetes (T2D). However, in Japan, whole grain intake remains low, with brown rice-a traditional whole grain-underutilized despite its demonstrated health benefits. This study aimed to explore the health and economic impacts of increasing brown rice consumption among Japanese adults aged 40-79 years.

METHODS

Using a discrete-time Markov cohort macro-simulation model, we projected the effects of replacing 30% and 80% of mean white rice consumption with brown rice over 10 years. Input parameters were based on published epidemiological data and national healthcare expenditures. Key outcomes included cumulative T2D incidence, all-cause mortality, and associated healthcare costs.

RESULTS

Increasing brown rice consumption could prevent 1.3-3.4% of new T2D cases, avert 0.01-0.02% of all-cause deaths, and save from USD 31.3 million to USD 80.5 million in healthcare costs. Sensitivity analyses revealed that the relative risk of T2D associated with brown rice intake had the greatest influence on variabilities in projected cost savings.

CONCLUSIONS

Although the projected reductions in T2D and healthcare costs were modest, the findings highlight the potential of increased brown rice consumption to alleviate the economic and public health burden of T2D in Japan. Incorporating brown rice into dietary patterns may support multidisciplinary lifestyle approaches for T2D prevention. Further research is warranted to explore long-term care costs for the management of complications and the benefits of other whole grains in the Japanese diet.

How much does the carcinogenic risk of inorganic arsenic exposure from rice increase with higher brown rice consumption? An estimation for five regions around the world

Substituting brown rice for white rice can increase the carcinogenic risk of inorganic arsenic (iAs) exposure, given that brown rice has a higher iAs content than white rice. This study estimated changes in the incremental lifetime cancer risk (ILCR) of iAs exposure from rice with increases in the proportion of brown to total rice consumption (PBT) in five regions around the world, including North America, Latin America, Europe, Asia, and Oceania. The results demonstrated that the magnitude of the increase in the ILCR of iAs exposure from rice expressed as an increase in PBT, ranged from 0.02 to 0.43 per 10,000 people for each 10 % increase in PBT. The highest increase was observed in Asia, followed by Latin America, North America, Oceania, and Europe. The daily rice consumption rate rather than the increase in iAs content is the critical factor responsible for regional differences in higher carcinogenic risk with increased PBT. This study also suggests that when considering the carcinogenic risks of iAs exposure from rice, substituting brown rice for white rice is feasible in North America and Europe but not in Asia and Latin America, while in Oceania, a partial substitution of brown rice for white rice (<55 %) is feasible.

Food Preference Assessed by the Newly Developed Nutrition-Based Japan Food Preference Questionnaire and Its Association with Dietary Intake in Abdominal-Obese Subjects

BACKGROUND/OBJECTIVES

Understanding food preferences is important for weight management. However, methods for assessing food preferences are not well established, especially in Japan. This study aimed to examine detailed food preferences and their associations with actual food intake in non-obese and abdominal-obese subjects using a newly developed questionnaire tailored for the Japanese population.

METHODS

We developed the Japan Food Preference Questionnaire (JFPQ) to evaluate food preferences across four nutrient groups based on nutritional evidence: carbohydrate, fat, protein, and dietary fiber. A total of 38 non-obese and 30 abdominal-obese participants completed both the JFPQ and the Food Frequency Questionnaire (FFQ). Food preferences for each nutrient were compared between the two groups, and correlations between food preferences (assessed by the JFPQ) and food intake (assessed by the FFQ) were analyzed.

RESULTS

Compared with the non-obese group, the abdominal-obese group showed significantly greater preferences for carbohydrates, fat, and protein, with no significant difference in dietary fiber after adjusting for age and sex. Furthermore, in the abdominal-obese group, positive correlations were found between actual intake and preference for high-fat and high-carbohydrate foods.

CONCLUSIONS

Our findings from this pilot study demonstrated that abdominal-obese individuals had greater preferences for fat and carbohydrates, which were linked to actual fat and carbohydrate intake and possibly contributed to the development of obesity.

The Consumption of High-Amylose Rice and its Effect on Postprandial Blood Glucose Levels: A Literature Review

Background/Objectives: Rice is a major staple in the diets of East Asian populations. Numerous meta-analyses have shown an association between high white rice consumption and a higher risk of diabetes. High-amylose rice (varieties with over 25% amylose content) is absorbed more slowly in the gut compared to low-amylose rice, and it results in lower levels of postprandial blood glucose. Various intervention studies have investigated the effects of high-amylose rice consumption on postprandial blood glucose and the glycemic index. The quantity of the research suggests that a comprehensive review of these diverse findings is necessary. Methods and Results: We reviewed 17 clinical trials, most of which showed that high-amylose rice ingestion results in lower postprandial blood glucose levels and glycemic index compared to low-amylose rice diets. Although they differed in their sample size, study design, rice type and quantity, and amylose content, most of these studies suggested that there is a reasonable effect of high-amylose rice consumption on postprandial blood glucose. In particular, the effect on blood glucose suppression tended to be related to the amylose content. However, long-term intake studies are still limited and require further investigation. Conclusions: In conclusion, high-amylose rice shows promise for blood glucose management.

Diet-Wide Association Study for the Incidence of Type 2 Diabetes in Three Population-Based Cohorts

BACKGROUND

Dietary factors are well-known modifiable risk factors for type 2 diabetes (T2D), but many studies overlook the interrelationships between these factors, even though foods are often consumed together and contain a variety of nutrients.

OBJECTIVES

In this study, we employed a diet-wide association study approach to investigate the links between various dietary factors and T2D onset, taking into account complex dietary patterns.

METHODS

We analyzed 16,666 participants without T2D from three Korean population-based cohorts: the Multi-Rural Communities Cohort (n = 8302), the Atherosclerosis Risk of a Rural Area Korean General Population cohort (n = 4990), and the Kanghwa cohort (n = 3374). A two-step approach was employed. In the first step, robust Poisson regression analysis was used for the initial screening (false discovery rate-adjusted p-values < 0.05). In the second step, a hierarchical cluster analysis was conducted of all dietary factors, followed by mutual adjustment of the screened factors within each cluster to account for interrelationships.

RESULTS

The 11 food clusters screened were cooked rice with beans, rice cakes, breads/spreads, bread products, cheese and pizza/hamburger, grain powder, snack/confections, nuts and roasted beans, soy milk, traditional beverages, and non-native fruit. These factors were similarly distributed across three of the seven clusters in each cohort. After mutual adjustment, cooked rice with beans (p-value ≤ 2.00 × 10-7 in all three cohorts) and non-native fruits (p-value ≤ 5.91 × 10-3 in two cohorts) remained significantly associated with lower T2D risk in more than one cohort.

CONCLUSIONS

The inverse association of cooked rice with beans, not observed with other types of cooked rice, and that of non-native fruits, suggest that incorporating beans into rice and eating various fruits may be an effective strategy for preventing diabetes.

Traditional rural dietary pattern and all-cause mortality in a prospective cohort study of elderly Costa Ricans: the Costa Rican Longevity and Healthy Aging Study (CRELES)

BACKGROUND

Costa Rica is experiencing a fast demographic aging. Healthy diets may help to ameliorate the burden of aging-related conditions.

OBJECTIVE

This study aimed to investigate the association of a traditional dietary pattern and 2 of its major components (beans and rice) with all-cause mortality among elderly Costa Ricans.

METHODS

The Costa Rican Longevity and Healthy Aging Study (CRELES), a prospective cohort study of 2827 elderly Costa Ricans (60+ y at baseline), started in 2004. We used a food frequency questionnaire (FFQ) to assess usual diet. We calculated dietary patterns using principal component analysis. Multivariate energy-adjusted proportional-hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Over a 15-y follow-up, encompassing 24,304 person-years, 1667 deaths occurred. The traditional Costa Rican dietary pattern was more frequent in rural parts of the country, and it was inversely associated with all-cause mortality. Subjects in the fifth quintile of intake had 18% lower all-cause mortality than those in the first quintile (HR: 0.82; 95% CI: 0.69, 0.98; P-trend = 0.01), particularly among males (HR: 0.73; 95% CI: 0.56, 0.95). Bean intake was associated with lower all-cause mortality among all subjects (HR: 0.79; 95% CI: 0.68, 0.91, highest compared with lowest tertile) and in sex-stratified analysis. Rice consumption was inversely associated with all-cause mortality solely among males (HR: 0.75; 95% CI: 0.60, 0.94, highest compared with lowest tertile).

CONCLUSIONS

Our results suggest that a traditional Costa Rican rural dietary pattern is associated with lower all-cause mortality in elderly Costa Ricans. Beans, a major component of this traditional dietary pattern, was also associated with lower all-cause mortality. These findings could have important implications for public health, given the nutritional transition and the reduction of intake of traditional diets in Latin American countries.

Impact of Rice Bran Oil Emulsified Formulation on Digestion and Glycemic Response to Japonica Rice: An In Vitro Test and a Clinical Trial in Adult Men

To assess the effect of rice bran oil emulsified formulation (EMF) on cooked rice, a single-arm open clinical trial and in vitro testing for digestion and glycemic response were performed. Fifteen Japanese men consumed 200 g of packed rice, cooked with or without EMF. Blood samples were collected 0, 30, 60, and 120 min post-consumption and analyzed for glucose, insulin, and triglyceride levels. Continuous glucose monitoring (CGM) and sensory evaluation were also performed. A two-step in vitro digestion test, simulating gastric and small intestinal digestion was conducted. EMF-added rice group showed higher insulin response levels at 60 min than the placebo group. Stratification of participants with HbA1c ≥ 5.6 or an insulinogenic index ≤ 0.4 revealed a significant reduction in Cmax glucose levels. A significant correlation was observed between venous and CGM blood glucose levels and no significant sensory differences were observed. The in vitro test revealed significantly lower C∞, equilibrium starch concentrations, with EMF. Clinical trial suggests that EMF may stimulate insulin secretion and reduce blood glucose levels in participants with lower insulin responses. In vitro tests suggest that EMF inhibits glycemic digestion. This trial was registered at the UMIN Center (UMIN000053495; registered 31 January 2024).

Evaluation of the trade-off between variety, processing, and low-GI claim in ready-to-eat rice

An increasing number of consumers demand healthier, more convenient, and sustainable food products, including rice, a staple worldwide. Food manufacturers have responded to this trend by considering food's intrinsic and extrinsic aspects. This study evaluated the importance of variety, processing, and claims on willingness to try ready-to-eat rice (RTE-rice). It also analyses the influence of consumer attitudes on the importance of attributes and willingness to try. The results showed that processing significantly influenced willingness to try RTE-rice, revealing consumers' greater preference for whole grain than milled rice with added bran. Claims had the least relevant importance. However, low glycaemic index had a positive impact, indicating its potential to influence consumer purchasing attitudes and promote healthier rice consumption. Additionally, three groups were created based on attitudinal factors. Naturalness-oriented and convenience-oriented groups were more likely to try RTE-rice. However, the reasons that motivate them may be different; this latter could be the ease of the service offered, while for the group focused on naturalness, they may have perceived through the ingredients and claimed that the product, despite being convenient, can bring benefits, thus perceiving them as natural.

Trends and Characteristics of Brown Rice Consumption among Adults in Japan: An Analysis of the National Health and Nutrition Surveys, 2012-2019

Brown rice is a familiar whole grain in Japan. We examined national trends in brown rice consumption among Japanese adults aged ≥20 years old, using individual-level data from the National Health and Nutrition Surveys conducted between 2012 and 2019. We employed multivariable logistic regression to identify factors associated with brown rice consumption. The 95th percentile of daily brown rice intake remained at 0.0 g throughout the study period. The percentage of brown rice consumers increased from 1.8% (95% confidence interval: 1.6-2.1) in 2012 to 2.6% (95% confidence interval: 2.0-3.4) in 2019. Compared with individuals who consumed only white rice, brown rice consumers had significantly higher mean intake levels of macronutrients, legumes, vegetables, fruits, and nuts. Brown rice consumption was positively associated with certain sociodemographic characteristics (being female, older age, residing in a major city, living without very young children, and having higher education levels) and health behaviors (lower body mass index, engaging in regular exercise, and being a former or never smoker). Despite its potential nutritional benefits in balanced diets, only a small fraction of adults in Japan consume brown rice, indicating a need for further promotion, particularly among individuals with characteristics associated with brown rice consumption.

Exploring Rice Consumption Habits and Determinants of Choice, Aiming for the Development and Promotion of Rice Products with a Low Glycaemic Index

Current consumption drivers, particularly those related to health and wellbeing, have been influencing trends for the lower consumption of cereals, particularly rice, due to their typical high glycaemic index (GIs) and consequent impacts on obesity. To satisfy this consumer concern, more food innovations that promote healthy eating habits are required. Such innovations must be consumer-oriented to succeed, understanding the dynamics of consumer habits and responding to consumer expectations. This study explored these habits, from acquisition to consumption practices, and the expectations of the European market from the perspective of the major European consumer, Portugal, to obtain insights that support the development of low glycaemic index (GI) rice products. A mixed-methods approach was applied. For the first quantitative questionnaire, 256 Portuguese rice consumers aged 18-73 years were recruited. Twenty-four individuals were selected according to their gender and rice consumption profiles for in-depth interviews. The results confirmed that rice was the main side dish for the participants and was mainly consumed at home, cooked from raw milled rice. The drivers of consumption differ according to the provisioning process stage. In the acquisition stage, participants reported benefits from the rice's dynamic market by comparing products on price, brand, and rice types. In the preparation stage, participants reported the adequacy of the recipe and occasion, while in the consumption stage, participants enhanced their sensory preferences, depending on the rice dish. Although the GI concept was unknown to half of the participants, it was perceived as interesting and positive for healthy eating. Consumers showed concern about the taste and naturalness of the product, preferring it to be as close to a homemade dish as possible. The negative perceptions we verified were interpreted to be due to a lack of knowledge about the GI concept. Therefore, awareness actions and informative campaigns are recommended to promote low-GI rice products.

Multiple Trajectories of Cereal Consumption and Their Associations with Type 2 Diabetes in Chinese Adults - China, 1997-2018

What is already known about this topic?

Consuming refined grains, specifically white rice, elevates the risk of developing type 2 diabetes (T2D). Conversely, incorporating whole grains into the diet is linked to a reduced risk.

What is added by this report?

This study employed a novel multi-trajectory modeling technique to account for the intercorrelations among various cereal consumption patterns. Four distinct multi-trajectory groups of cereal intake, identified from 1997 to 2018 within the Chinese population, were associated with varying levels of T2D risk.

What are the implications for public health practice?

This research investigates the implications of evolving cereal consumption patterns on T2D in nondiabetic adults. This study delineates unique trajectories linked with cereal intake patterns, thereby providing a robust foundation for policymakers to craft initiatives to prevent T2D among adults in China.

Dietary Patterns Associated with Abnormal Glucose Tolerance following Gestational Diabetes Mellitus: The MyNutritype Study

Abnormal glucose tolerance (AGT), which includes type 2 diabetes and pre-diabetes, is highly prevalent in women post gestational diabetes mellitus (post-GDM). Dietary patterns have been associated with the risk of developing AGT in women post-GDM, but evidence in Asian populations is sparse. This study aimed to determine the association between a posteriori dietary patterns and AGT in women post-GDM. This cross-sectional study recruited 157 women post-GDM (mean age 34.8 years) from Seri Kembangan Health Clinic and Universiti Putra Malaysia. AGT was diagnosed according to the Malaysian Clinical Practice Guidelines using a 75 g 2 h oral glucose tolerance test or HbA1c. Food intake was assessed using the 2014 Malaysian Adult Nutrition Survey food frequency questionnaire. Five dietary patterns were derived using principal component analysis: 'Unhealthy', 'Fish-eggs-fruits-vegetables', 'Cereals-confectionaries', 'Legumes-dairy', and 'Meat-sugar-sweetened-beverages'. After adjusting for sociodemographic characteristics and total energy intake, the 'Cereals-confectionaries' dietary pattern was significantly associated with AGT (adjusted odds ratio 1.536, p = 0.049). Targeted lifestyle modification, including dietary intervention, for women post-GDM is warranted to reduce their risk of AGT and its complications.