An open label randomized controlled trial of the effects of rice bran oil on cardiometabolic risk factors, lipid peroxidation and antioxidant status in overweight/obese adults with metabolic syndrome

Introduction We previously documented the beneficial effects of rice bran oil (RBO) on cardiac function and atherogenic cardiometabolic factors in men with coronary artery disease. Therefore, the existing evidence in this area aims to be expanded by investigating the impact of adding RBO to a daily standard diet on emerging insulin resistance surrogate markers, lipid peroxidation, antioxidant status, and metabolic disturbances in individuals with metabolic syndrome (MetSyn) through an open-label controlled trial. Methods A total of 50 overweight/obese adults (mean body mass index (BMI) = 31.08 kg/m2) with at least 3 MetSyn components were randomly allocated to either the control group, which received a standard diet plan, or the intervention group, which was supplemented with 30 g/d RBO for 8 weeks. BMI, MetSyn components, metabolic score for insulin resistance (METS-IR), triglyceride-glucose-BMI (TyG-BMI), malondialdehyde (MDA), total antioxidant capacity (TAC), and plasma polyphenol levels were measured before and after this open-label trial. Results Analysis of covariance (ANCOVA) adjusted for baseline values revealed that, compared with patients who received only a standard diet, those who were supplemented with 30 g/d RBO presented significantly lower total cholesterol (P value = 0.005; effect size (ES):-0.92), LDL-cholesterol (P value = 0.048; ES:-0.62), fasting blood glucose (P value = 0.014; ES:-0.77), MDA (P value = 0.002; ES: -1.01), METS-IR (P value < 0.001; ES: -1.24), and TyG-BMI (P value = 0.007; ES:-0.85) after 8 weeks. Additionally, RBO consumption resulted in significantly higher levels of HDL-C (P value = 0.004; ES:0.94) and TAC (P value < 0.0001; ES:2.05). However, no significant changes were noted in BMI, waist circumference, serum triglycerides, plasma polyphenols, or blood pressure. Conclusion Although the current findings suggest that the hypocholesterolemic, antihyperglycemic, and antioxidative effects of 30 g/d RBO seem to be promising for MetSyn patients, they should be considered preliminary. Therefore, further well-designed clinical trials with larger sample sizes and longer durations are needed to confirm these findings.