Substituting brown rice for white rice on diabetes risk factors in India: a randomised controlled trial.

2019-06-21
The British journal of nutrition 121(12)
- V S Malik
- V Sudha
- N M Wedick
- M RamyaBai
- P Vijayalakshmi
- N Lakshmipriya
- R Gayathri
- A Kokila
- C Jones
- B Hong
- R Li
- K Krishnaswamy
- R M Anjana
- D Spiegelman
- W C Willett
- F B Hu
- V Mohan

PubMed: 31006420
DOI: 10.1017/s000711451900076x

Study Design

Type: Randomized Controlled Trial (RCT)
Sample size: n = 166
Population: 166 overweight (BMI ≥ 23 kg/m2) adults aged 25-65 years
Methods: randomised cross-over trial, parboiled brown rice or white rice regimen providing two ad libitum meals/d, 6 d/week for 3 months with a 2-week washout period
Blinding: Open-label
Duration: 3 months
Funding: Unclear

Large Human Trial

India has the second largest number of people with type 2 diabetes (T2D) globally. Epidemiological evidence indicates that consumption of white rice is positively associated with T2D risk, while intake of brown rice is inversely associated. Thus, we explored the effect of substituting brown rice for white rice on T2D risk factors among adults in urban South India. A total of 166 overweight (BMI ≥ 23 kg/m2) adults aged 25-65 years were enrolled in a randomised cross-over trial in Chennai, India. Interventions were a parboiled brown rice or white rice regimen providing two ad libitum meals/d, 6 d/week for 3 months with a 2-week washout period. Primary outcomes were blood glucose, insulin, glycosylated Hb (HbA1c), insulin resistance (homeostasis model assessment of insulin resistance) and lipids. High-sensitivity C-reactive protein (hs-CRP) was a secondary outcome. We did not observe significant between-group differences for primary outcomes among all participants. However, a significant reduction in HbA1c was observed in the brown rice group among participants with the metabolic syndrome (-0·18 (se 0·08) %) relative to those without the metabolic syndrome (0·05 (se 0·05) %) (P-for-heterogeneity = 0·02). Improvements in HbA1c, total and LDL-cholesterol were observed in the brown rice group among participants with a BMI ≥ 25 kg/m2 compared with those with a BMI < 25 kg/m2 (P-for-heterogeneity < 0·05). We observed a smaller increase in hs-CRP in the brown (0·03 (sd 2·12) mg/l) compared with white rice group (0·63 (sd 2·35) mg/l) (P = 0·04). In conclusion, substituting brown rice for white rice showed a potential benefit on HbA1c among participants with the metabolic syndrome and an elevated BMI. A small benefit on inflammation was also observed.

Research Insights

brown rice→Increased HDL Cholesterol Levels
We did not observe significant between-group differences for primary outcomes among all participants.
Effect
Neutral
Effect size
Small
brown rice→Reduced Blood Cholesterol
Improvements in total and LDL-cholesterol were observed in the brown rice group among participants with a BMI ≥ 25 kg/m2 compared with those with a BMI < 25 kg/m2 (P-for-heterogeneity < 0·05).
Effect
Beneficial
Effect size
Small
brown rice→Reduced C-Reactive Protein Levels
We observed a smaller increase in hs-CRP in the brown (0·03 (sd 2·12) mg/l) compared with white rice group (0·63 (sd 2·35) mg/l) (P = 0·04).
Effect
Beneficial
Effect size
Small
brown rice→Reduced Fasting Blood Glucose Levels
We did not observe significant between-group differences for primary outcomes among all participants.
Effect
Neutral
Effect size
Small
brown rice→Reduced HOMA-IR
We did not observe significant between-group differences for primary outcomes among all participants.
Effect
Neutral
Effect size
Small
brown rice→Reduced Hemoglobin A1c
Improvements in HbA1c were observed in the brown rice group among participants with a BMI ≥ 25 kg/m2 compared with those with a BMI < 25 kg/m2 (P-for-heterogeneity < 0·05).
Effect
Beneficial
Effect size
Small
brown rice→Reduced Insulin Levels
We did not observe significant between-group differences for primary outcomes among all participants.
Effect
Neutral
Effect size
Small
brown rice→Reduced LDL Cholesterol
Improvements in total and LDL-cholesterol were observed in the brown rice group among participants with a BMI ≥ 25 kg/m2 compared with those with a BMI < 25 kg/m2 (P-for-heterogeneity < 0·05).
Effect
Beneficial
Effect size
Small
brown rice→Reduced Triglyceride Levels
We did not observe significant between-group differences for primary outcomes among all participants.
Effect
Neutral
Effect size
Small