Department of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
Women's College Hospital, Toronto, Ontario, Canada.
BMJ Open. 2022 Sep 27;12(9):e065426. doi: 10.1136/bmjopen-2022-065426.
Intake 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.
Systematic review and meta-analysis.
PubMed, EMBASE and Cochrane databases were searched through November 2021.
Prospective 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 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.
Nineteen 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.
Intake 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.
CRD42020158466.
白米饭的摄入与 2 型糖尿病（T2D）风险增加有关，而关于糙米的研究则存在矛盾。为了提供饮食指导，我们综合了白米和糙米与 T2D 风险的相关证据。
系统评价和荟萃分析。
通过 2021 年 11 月对 PubMed、EMBASE 和 Cochrane 数据库进行检索。
白米和糙米摄入量与 T2D 风险（≥1 年）相关的前瞻性队列研究，以及比较糙米和白米对心血管代谢风险因素影响的随机对照试验（RCTs）（≥2 周）。
主要审查员和另外两名审查员提取数据。使用随机效应模型进行荟萃分析，并按照系统评价和荟萃分析的 Preferred Reporting Items 指南进行报告。使用纽卡斯尔-渥太华量表评估前瞻性队列研究的偏倚风险，使用 Cochrane 偏倚风险工具评估 RCTs 的偏倚风险。使用 NutriGrade 评估荟萃分析证据的强度。
共纳入 19 篇文章：8 项队列研究提供了 18 项估计值（白米：15 项估计值，25956 例，n=577426；糙米：3 项估计值，10507 例，n=197228）和 11 项 RCT（n=1034）。在队列研究中，与极端类别相比，白米与 T2D 风险增加相关（汇总 RR，1.16；95%CI：1.02 至 1.32）。在摄入量超过~300g/天以上时，观察到剂量反应（每 158g/天的摄入量与 13%（11%-15%）更高的 T2D 风险相关）。与极端类别相比，摄入糙米与 T2D 风险降低相关（汇总 RR，0.89；95%CI：0.81 至 0.97）。与白米相比，每 50g/天的糙米摄入量与 13%（6%-20%）更低的 T2D 风险相关。队列研究被认为质量良好或中等。RCT 显示，与白米相比，糙米组的高密度脂蛋白胆固醇（HDL-C）增加了 0.06mmol/L（0.00 至 0.11mmol/L）。未观察到其他风险因素的显著差异。大多数 RCT 被认为存在一定的偏倚风险。荟萃分析证据的整体强度为队列研究为中度，RCT 为中度和低度。
白米摄入与 T2D 风险增加有关，而糙米摄入与 T2D 风险降低有关。关于心血管代谢风险因素的替代试验结果不一致。
CRD42020158466。
