The effect of brown rice compared to white rice on adiposity indices, lipid profile, and glycemic markers: a systematic review and meta-analysis of randomized controlled trials

A few randomized controlled trials (RCTs) have assessed the effect of brown rice consumption on metabolic parameters compared to white rice, with inconsistent findings. Therefore, the present systematic review and meta-analysis was designed to evaluate the effect of brown rice on adiposity indices, lipid profile, and glycemic markers in adult subjects compared to white rice. In this study, PubMed/Medline, Scopus, Web of Sciences, and Embase databases were comprehensively searched until March 2021. Thirteen RCTs were selected and then included in the meta-analysis. As reported, brown rice significantly reduced weight by -1.63 kg (95% CI: -2.15 to -1.11, I²=97%, n = 6), body mass index (BMI) by -0.58 kg/m² (95% CI: -0.78 to -0.37, I²=96%, n = 6), and waist circumference by -2.56 cm (95% CI: -4.86 to -0.26, I²=88%, n = 5) compared with white rice. Moreover, it had no significant effect on lipid profile and glycemic markers. Besides, pre-germinated brown rice significantly declined weight (-1.75 kg, 95% CI: -2.70 to -0.81, I²=99%, n = 4), total cholesterol (-24.22 mg/dl, 95% CI: -33.03 to -15.41, I²=78%, n = 5), triglyceride (TG) (-43.28 mg/dl, 95% CI: -74.05 to -12.50, I²=90%, n = 5), low-density lipoprotein (LDL) (-20.05 mg/dl, 95% CI: -29.57 to -10.52, I²=71%, n = 5), and fasting blood glucose (FBG) (-15.83 mg/dl, 95% CI: -25.20 to -6.46, I²=91%, n = 5). In accordance with Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, the certainly of the included evidence was low and very low. The results of the present study indicate that, brown rice has anti-obesity effects in comparison with white rice; however, it has no beneficial effects on lipid profile and glycemic markers. Contrary to brown rice, it was shown that, pre-germinated brown rice significantly decreases body weight and improves lipid profile and FBG levels compared to white rice. Accordingly, our results indicate that, pre-germinated brown rice has better functional effects on promoting lipid profile and FBG compared to brown rice.