Zhang 2011.
| Study characteristics | ||
| Methods |
Setting: China Design: parallel‐group RCT (stratified by sex and 5‐year age category) Dates: 2009 onwards (initial screening conducted in 2009) Intervention duration: 16 weeks Follow‐up: no postintervention follow‐up Focus: to compare the effects of replacing white rice with brown rice in the diets of middle‐aged Chinese men and women with diabetes or a high risk for diabetes. |
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| Participants | Faculty and staff of a large university in Shanghai who had metabolic syndrome. N: 202 randomised (to 2 groups); 193 completed overall. 98/101 completers in brown rice group; 95/101 completers in white rice group. Inclusion criteria: people with MetS defined as presenting with at least 3 of the following components:
Exclusion criteria: history of severe kidney disease, cardiovascular disease, stroke, cancer, or psychological disorders as well as pregnant or lactating women were excluded. Age (years): white rice group: 49.8 SD 7.1; brown rice group: 49.6 SD 6.7 Sex (% men): white rice group: 53.5%; brown rice group: 53.5% Ethnicity: Chinese Baseline cardiovascular risk status: mean (SD) or (95% confidence interval (CI)) BMI (kg/m2): white rice: 25.4 SD 2.5; brown rice: 25.9 SD 3.4; P = 0.22 Total cholesterol (mmol/L): white rice: 5.55 SD 1.33; brown rice: 5.44 SD 1.27; P = 0.55 HDL cholesterol (mmol/L): white rice: 1.31 SD 0.38; brown rice: 1.22 SD 0.34; P = 0.08 LDL cholesterol (mmol/L): white rice: 3.93 SD 8; brown rice: 3.81 SD 1; P = 0.46 Triglycerides (mmol/L): white rice: 1.78 (95% CI 1.21 to 2.39); brown rice: 1.81 (95% CI 1.30 to 2.53); P = 0.48 Systolic blood pressure (mmHg): white rice: 129 SD 15; brown rice: 129 SD 16; P = 0.82 Diastolic blood pressure (mmHg): white rice: 85 SD 10; brown rice: 86 SD 10; P = 0.42 Medications used: antihypertensive agents (% using): white rice: 44.6; brown rice: 29.7; P = 0.03 hypoglycaemic agents (% using): white rice: 5.0; brown rice: 4.0; P = 0.73 lipid‐lowering agents (% using): white rice: 3.0; brown rice: 3.0; P = 1.00 |
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| Interventions |
White rice: the 2 types of rice in the study were from the same batch; the white rice was produced by further milling the brown rice. Both types of rice were cooked in the same steam box under the same conditions. Brown rice: from the same batch as the white rice as described above. Description of dietary intervention: the cooked rice was packaged into 225 g servings (equivalent to 100 g cooked rice) and provided to participants at designated university campus cafeterias during the lunch hour from Monday to Fridays. Participants took cooked rice home for dinner and meals on Saturdays. They were encouraged to eat ad libitum and were permitted to consume other staple foods only on Sundays. They were instructed to maintain their usual dietary pattern regarding other food selections. Incentives: not reported Co‐interventions in both groups: none Assessment of dietary adherence: compliance was monitored by researchers weighing leftovers in the cafeteria and was calculated as the frequency of consumption of the prescribed type of rice divided by the frequency of consumption of total staple carbohydrates throughout the intervention. Participants recorded the amount of rice they consumed at home using electronic scales provided by the researchers. Dietary intake measured using a 3‐day diet record was obtained at baseline and every 4 weeks during follow‐up. Was the diet energy reduced? no Comparability of diet composition: adherence to diets was high: mean adherence 90.0 +/‐ 17.1% in the white rice group and 88.7 +/‐ 23.3% in the brown rice group; P for difference = 0.20. There was no difference in energy intake between groups over the intervention period, but lower intake of carbohydrates (P = 0.03) and dairy products in the brown rice group (P = 0.02). There was no difference in protein, fat, dietary cholesterol, vegetables, fruits, red meat, poultry, or seafood. Dietary fibre was higher in the brown rice group, as would be expected (P < 0.0001). (See Table 2.) Change in diet over time: reported at weeks 4, 8, 12, and 16. (See Table 2.) |
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| Outcomes | BMI, waist circumference, systolic blood pressure, diastolic blood pressure, total cholesterol, LDL cholesterol, HDL cholesterol, total:HDL cholesterol ratio, triglycerides, glucose, insulin, HOMA‐IR | |
| Funding/conflicts of interest | Supported by Chief Scientist Program of Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, National Basic Research Program of China, National Natural Science Foundation of China. | |
| Notes | No between‐group differences were found for any markers except serum LDL concentration, which decreased more in the white rice group that in the brown rice group (P = 0.02). However, this effect was only observed among participants with diabetes (n = 47). Among participants with diabetes, a greater reduction in diastolic blood pressure was observed in the brown rice group than in the white rice group (P = 0.02). | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | "randomly assigned (stratified by sex and 5y age category)", but method of randomisation not reported |
| Allocation concealment (selection bias) | Unclear risk | Not reported |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | All researchers not directly in contact with study participants (dietitians, laboratory technicians, and statisticians) were unaware of group allocations. Not possible for participants to be unaware of their group assignment due to differences in appearance and texture of the brown and white rice. |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | 98/101 completers in brown rice group; 95/101 completers in white rice group. The 6 withdrawals in the white rice group were due to busy schedule (n = 4); loss of interest (n = 1); or stroke unrelated to intervention. The 3 withdrawals in the brown rice group were due to a busy schedule or heart disease unrelated to the intervention. |
| Intention to treat analysis | Low risk | Intention‐to‐treat analysis done for all relevant outcomes. |
| Selective reporting (reporting bias) | Unclear risk | All outcomes of relevance to this review that were reported at baseline were reported at follow‐up. |
| Groups comparable at baseline | Unclear risk | Higher proportion of participants with diabetes (P = 0.03) and participants on antihypertensive medication (P = 0.03) in the white rice group at baseline |
| Other bias | Unclear risk | Sample size calculation based on fasting glucose outcome, which is not a relevant outcome for this review. |
% E: percentage energy ALT/AST: alanine transaminase/aspartate transaminase BMI: body mass index BP: blood pressure CVD: cardiovascular disease FFQ: Food Frequency Questionnaire FPG: fasting plasma glucose FSIGT: frequently sampled intravenous glucose tolerance test HDL: high‐density lipoprotein ITT: intention‐to‐treat LDL: low‐density lipoprotein MITT: modified intention‐to‐treat NEFA: non‐esterified fatty acids OGTT: oral glucose tolerance test PUFA: polyunsaturated fatty acid RCT: randomised controlled trial SD: standard deviation SEM: standard error of the mean TAG: triacylglyceride TC/HDL: total cholesterol/HDL cholesterol TG: triglycerides WG: whole grain