Characteristics of RCTs replacing white rice with brown rice on type 2 diabetes (T2D) risk factors
| Author | Design | Participants (location, n, % female, age, health status) | Duration (weeks) | Intervention diet | Control diet | Cooking method | Amount consumed | Dietary assessment for adherence | RoB-2* |
| Zhang et al 201126 | Parallel | Shanghai, China: n=202; %female=47; mean age ~50 year; MetS | 16 | Cooked BR packed for 225 g/day from Monday to Saturday (n=101) | Cooked WR packed for 225 g/day from Monday to Saturday (n=101) | Steamed under 0.3 MPa for ~75 min, with R:W ratios† of 1:1 for WR and 1:1.25 for BR (‡BR soaked for at least 1 hour before cooking) | Ad libitum, and allowed to consume with other staple foods on Sundays | 3-day food record | Low risk |
| Wang et al 201327 | Parallel | Chinese American: n=57; %female=38; prediabetic | 12 | BR (n=28) | WR (n=29) | Boiled in water for 30 min | Ad libitum based on usual intake | 3-day food record | Some concern |
| Kazemzadeh et al 201428 | Cross-over | Iran: n=40; %female=100; aged 18–50 year; healthy | 6 | 150 g/day cooked BR (n=20) | 150 g/day cooked WR (n=20) | Raw rice packaged and provided to participants to prepare at home | 150 g/day cooked rice | 3-day food record | Some concern |
| Bui et al 201435 | Parallel | Vietnam: n=60; %female=100; aged 45–65 year; IGT | 16 | 540 g/day PGBR (n=30) | 540 g/day WR (n=30) | Not specified | 540 g/day with normal activities of daily life without restriction | 24-hour diet recall | High risk |
| Shimabukuro et al 201434 | Cross-over | Japan: n=27; %female=0; age 41 year; MetS | 8 | 150 g/day BR (n=14) | 150 g/day WR (n=13) | Not specified | 150 g/day with regular dietary intake/exercise habits | Self-recorded compliance | Some concern |
| Geng et al 201632 | Parallel | Wuxi, China: n=191; %female=49.74; aged 40–70 year; dyslipidaemia | 12 | 150 g/day cooked PGBR (n=94; female=49) | 150 g/day cooked WR (n=97; female=47) | Processed and prepared by patent agent | 150 g/day without change in dietary habits and lifestyle | Semi-Quantitative Food Frequency Questionnaire (SQFFQ) carried by trained staff | Some concern |
| Araki et al 201729 | Parallel | Japan: n=41; %female=53.7; aged 40–64 year; prediabetic | 12 | 200 g cooked PABR twice a day (n=20; female=10) | 200 g cooked WR twice a day (n=21; female=12) | Steamed under cooking mode for WR, with R:W ratios of 1:1 for WR and 1:2 for PABR | 400 g/day with additional ad libitum consumption of staple foods for one daily meal | Brief self-administered Diet History Questionnaire (BDHQ) confirmed by dietician | Some concern |
| Malik et al 201930 | Cross-over | Chennai, India: n=166; %female=45; aged 25–65 year; overweight | 12 | Parboiled BR (strain: BPT5204)(n=85) | Non-parboiled WR (strain: BPT5204)(n=81) | Prepared by trained dietitians, and pressure cooked with R:W ratios of 1:2.5 for WR and 1:2 for BR | Two ad libitum meals/day | Direct observation and 24-hour diet recall | Some concern |
| Kuroda et al 201933 | Parallel | Japan: n=52; %female=51.9; aged ≥65 year; healthy | 104 | 100 g/day UHHPBR (n=27) | 100 g/day WR (n=25) | Supplied from the company | 100 g/day cooked rice | A general questionnaire on lifestyle, and BDHQ | Some concern |
| Mai et al 202031 | Parallel | Vietnam: n=80; %female=80; aged 55–70 year; MetS | 13 | 200 g/day PGBR (n=40; female=36) | 200 g/day WR (n=40; female=36) | Packaged in a 2 kg capsule per day | 200 g/day for 10 days each time without changes in lifestyle and medicine taking | SQFFQ | Low risk |
| Ren et al 202015 | Parallel | China: n=112; %female=44.6; aged 18–70 year; MetS | 4 | Cooked BR (n=28) | Cooked polished rice (n=28) | Washed and soaked in clear water with R:W ratio of 1:1.35 for 30 min. Then cooked in an electric cooker for 30 min and kept at temperature for 10 min | 100 g rice (50 g sample rice and 50 g polished rice), coupled with 30 g sauced beef, 150 g salad and 50 g eggs | Not specified | High risk |
*RoB-2=risk of bias 2.0.
†R:W ratio=rice-to-water ratio (in weight).
‡Conversion from uncooked rice to cooked rice by multiplying 2.5.
BR, brown rice; IGT, impaired glucose tolerance; MetS, metabolic syndrome; n, number of participants; PABR, partially abraded brown rice; PGBR, pregerminated brown rice; RCTs, randomised controlled trials; UHHPBR, ultra high hydrostatic pressurising brown rice; WR, white rice.