The effect of a brown-rice diets on glycemic control and metabolic parameters in prediabetes and type 2 diabetes mellitus: a meta-analysis of randomized controlled trials and controlled clinical trials

Rahim, Anis Farhanah Abdul; Norhayati, Mohd Noor; Zainudin, Aida Maziha

doi:10.7717/peerj.11291

Cited by 5 publications

(7 citation statements)

References 26 publications

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“…While the findings of our meta-analyses of cohort studies support the replacement of white rice with brown rice for T2D risk mitigation, findings from our meta-analysis of RCTs replacing white rice with brown rice on T2D risk factors were inconsistent with a significant benefit observed only for HDL-cholesterol and SBP, although findings for SBP were null in the fixed-effects model. These results are in agreement with a previous meta-analysis of RCTs of brown rice on metabolic parameters that also found a benefit on HDL-cholesterol, 12 although another meta-analysis of RCTs found no effect of brown rice compared with white rice on HDL-cholesterol. 13 Both of these meta-analyses, included fewer studies than ours, and combined study populations with prediabetes and T2D, which could have different effects on metabolism.…”

Section: Discussionsupporting

confidence: 92%

“…However, these meta-analyses also found a benefit of brown rice compared with white rice on body weight, which was not assessed in our meta-analysis, suggesting a therapeutic role of brown rice on weight management among patients with prediabetes and T2D. 12 Reasons for the discrepant results between our meta-analyses of cohort studies and trials may be due to the low quality and methodological limitations of the included trials including small sample size, high drop-out rates and difficulty monitoring compliance. The duration of the majority of studies ranged from 4 to 16 weeks, which may have been insufficient to detect meaningful changes in clinical indices among predominately healthy populations.…”

Section: Discussioncontrasting

confidence: 70%

“…Two recent meta-analyses of RCTs found a benefit of brown rice compared with white rice on body weight but discrepant results on waist circumference and lipid parameters. 12 13 However, these meta-analyses combined studies conducted among participants with and without T2D, which may have differential effects on macronutrient metabolism. To provide a current synthesis of the evidence, we conducted an updated systematic review and meta-analysis of cohort studies that examined intake of white rice and risk of T2D including a dose–response analysis.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to cohort studies, findings from randomised controlled trials (RCTs) comparing white rice with brown rice have been inconsistent. Two recent meta-analyses of RCTs found a benefit of brown rice compared with white rice on body weight but discrepant results on waist circumference and lipid parameters 12 13. However, these meta-analyses combined studies conducted among participants with and without T2D, which may have differential effects on macronutrient metabolism.…”

Section: Introductionmentioning

confidence: 99%

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

Bhavadharini

Tinajero

et al. 2022

BMJ Open

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ObjectiveIntake of white rice has been associated with elevated risk for type 2 diabetes (T2D), while studies on brown rice are conflicting. To inform dietary guidance, we synthesised the evidence on white rice and brown rice with T2D risk.DesignSystematic review and meta-analysis.Data sourcesPubMed, EMBASE and Cochrane databases were searched through November 2021.Eligibility criteriaProspective cohort studies of white and brown rice intake on T2D risk (≥1 year), and randomised controlled trials (RCTs) comparing brown rice with white rice on cardiometabolic risk factors (≥2 weeks).Data extraction and synthesisData were extracted by the primary reviewer and two additional reviewers. Meta-analyses were conducted using random-effects models and reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Risk of bias was assessed using the Newcastle Ottawa Scale for prospective cohort studies and the Cochrane Risk of Bias Tool for RCTs. Strength of the meta-evidence was assessed using NutriGrade.ResultsNineteen articles were included: 8 cohort studies providing 18 estimates (white rice: 15 estimates, 25 956 cases, n=5 77 426; brown rice: 3 estimates, 10 507 cases, n=1 97 228) and 11 RCTs (n=1034). In cohort studies, white rice was associated with higher risk of T2D (pooled RR, 1.16; 95% CI: 1.02 to 1.32) comparing extreme categories. At intakes above ~300 g/day, a dose–response was observed (each 158 g/day serving was associated with 13% (11%–15%) higher risk of T2D). Intake of brown rice was associated with lower risk of T2D (pooled RR, 0.89; 95% CI: 0.81 to 0.97) comparing extreme categories. Each 50 g/day serving of brown rice was associated with 13% (6%–20%) lower risk of T2D. Cohort studies were considered to be of good or fair quality. RCTs showed an increase in high-density lipoprotein-cholesterol (0.06 mmol/L; 0.00 to 0.11 mmol/L) in the brown compared with white rice group. No other significant differences in risk factors were observed. The majority of RCTs were found to have some concern for risk of bias. Overall strength of the meta-evidence was moderate for cohort studies and moderate and low for RCTs.ConclusionIntake of white rice was associated with higher risk of T2D, while intake of brown rice was associated with lower risk. Findings from substitution trials on cardiometabolic risk factors were inconsistent.PROSPERO registration numberCRD42020158466.

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Section: Discussionsupporting

confidence: 92%

Section: Discussioncontrasting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Bhavadharini

Tinajero

et al. 2022

BMJ Open

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“…This phenomenon was supported by two recent meta‐analyses. A meta‐analysis found that the consumption of whole grain foods acutely improved postprandial glucose compared with controls in healthy participants 11 , but the inverse association disappeared when the included participants were prediabetes and type 2 diabetes mellitus patients from the research of Rahim's et al 49 . Furthermore, animal studies also showed that the intake of whole grain has no significant effect on glycemic measures in diabetic rodents.…”

Section: Discussionmentioning

confidence: 99%

Effects of whole grain intake on glycemic control: A meta‐analysis of randomized controlled trials

Li¹,

Yan

Chen³

et al. 2022

J of Diabetes Invest

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Aims/Introduction Although mounting evidence has suggested an inverse association between the intake of whole grains and glycemic control, findings from randomized controlled trials are still conflicting. The current study was carried out to evaluate the effect of medium/long‐term whole grain intake on glycemic control in metabolic syndrome and healthy populations. Materials and Methods A literature search was carried out to identify qualified studies up to July 2021. The effects of whole grain consumption on glycemic control were calculated using a fixed effects model. Subgroup analysis was used to study whether grouping factors were important influencing factors of heterogeneity between research results. Results A total of 32 randomized controlled trials with 2,060 participants were included in the analyses. Whole grain consumption showed a significant inverse regulatory effect on fasting glucose concentration, but no significant effect was found for other glycemic measures, such as fasting insulin, homeostatic model assessment for insulin resistance, glycated hemoglobin and 2‐h glucose, in the pooled analysis. Through subgroup analyses, a significant decrease in fasting glucose concentration was observed for studies with a higher whole grain dose, with participants of normal glycemia, and with mixed types of whole grain. Conclusions Medium‐/long‐term whole grain intake reduced the fasting glucose concentration compared with similar refined foods. Appropriate intervention dose and accurate population selection might be the key links for whole grain consumption to exert its glycemic control effect.

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Associations between dietary fiber intake and cardiovascular risk factors: An umbrella review of meta-analyses of randomized controlled trials

Zhang

Qian

et al. 2022

Front. Nutr.

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Although several meta-analyses have revealed the beneficial effects of dietary fiber intake on human health, some have reported inconsistent findings. The purpose of this work was to perform an umbrella meta-analysis to evaluate the relevant evidence and elucidate the effect of dietary fiber intake on glycemic control, lipid profiles, systematic inflammation, and blood pressure. Eligible studies were searched in several electronic databases, including Web of Science, PubMed, Scopus, and the Cochrane Library, up to March 2022. A total of 52 meta-analyses involving 47,197 subjects were identified to assess the pooled effect size. Overall, higher dietary fiber intake was significantly associated with reductions in parameters involving glycemic control, including fasting plasma glucose (ES = −0.55, 95% CI: −0.73, −0.38, P < 0.001), fasting plasma insulin (ES = −1.22, 95% CI: −1.63, −0.82, P < 0.001), homeostasis model assessment of insulin resistance (HOMA-IR) (ES = −0.43, 95% CI: −0.60, −0.27, P < 0.001), and glycosylated hemoglobin (HbA1c) (ES = −0.38, 95% CI: −0.50, −0.26, P < 0.001). In terms of lipid profiles, higher dietary fiber intake was associated with significant reductions in the serum level of total cholesterol (ES = −0.28, 95% CI: −0.39, −0.16, P < 0.001) and low-density lipoprotein cholesterol (ES = −0.25, 95% CI: −0.34, −0.16, P < 0.001), but not triglycerides (ES = −0.001, 95% CI: −0.006, 0.004, P = 0.759) and high-density lipoprotein cholesterol (ES = −0.002, 95% CI: −0.004, 0.000, P = 0.087). Higher dietary fiber intake was also significantly associated with improved tumor necrosis factor-alpha serum levels (ES = −0.78, 95% CI: −1.39, −0.16, P = 0.013), while no significant effect was observed for C-reactive protein (ES = −0.14, 95% CI: −0.33, 0.05, P = 0.156). Finally, blood pressure was also significantly improved following higher dietary fiber intake (systolic blood pressure: ES = −1.72, 95% CI: −2.13, −1.30, P < 0.001; diastolic blood pressure: ES = −0.67, 95% CI: −0.96, −0.37, P < 0.001). Subgroup analysis revealed that the study population and type of dietary fiber could be partial sources of heterogeneity. In conclusion, the present umbrella meta-analysis provides evidence for the role of dietary fiber supplementation in the improvement of established cardiovascular risk factors.

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The effect of a brown-rice diets on glycemic control and metabolic parameters in prediabetes and type 2 diabetes mellitus: a meta-analysis of randomized controlled trials and controlled clinical trials

Cited by 5 publications

References 26 publications

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

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

Effects of whole grain intake on glycemic control: A meta‐analysis of randomized controlled trials

Associations between dietary fiber intake and cardiovascular risk factors: An umbrella review of meta-analyses of randomized controlled trials

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