Rice Bran Oil Containing Gamma-Oryzanol Improves Lipid Profiles and Antioxidant Status in Hyperlipidemic Subjects: A Randomized Double-Blind Controlled Trial

Objectives: Rice bran oil (RBO) is a major source of monounsaturated fatty acid and gamma-oryzanol, which may assist in lowering blood lipids and oxidative stress. This study examined the effects of RBO containing different amounts of gamma-oryzanol on blood lipid, antioxidant, and inflammatory markers. Materials and methods: A total of 59 hyperlipidemic subjects completed the study. They were divided into four groups: RBO1 (4,000ppm gamma-oryzanol, n=14), RBO2 (8,000ppm gamma-oryzanol, n=15), RBO3 (11,000ppm gamma-oryzanol, n=15), and control (soybean oil, n=15). The assigned oil (30mL) was incorporated into three cooked meals each day for 4 weeks. Anthropometrical measurements and blood samples were taken to evaluate body weight, body composition, lipid parameters, antioxidant status, and inflammatory markers before and after the intervention. Results: Compared with the control, consumption of RBO significantly decreased low-density lipoprotein cholesterol (LDL-C) levels (percentage change: -0.8% [control]; -8% [RBO1]; -11.8% [RBO2]; and -12.2% [RBO3], p=0.012) with the greatest change found in RBO2 and RBO3. In addition, antioxidant status also improved significantly. Levels of oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) increased after consumption of a diet with RBO compared with consumption of a diet with soybean oil (ORAC: -2.7% [control]; 4.1% [RBO1]; 8.6% [RBO2]; and 10.1% [RBO3], p<0.001; FRAP: -4.4% [control]; 4.7% [RBO1]; 7.4% [RBO2]; and 7.6% [RBO3], p<0.001). Conclusions: RBO with gamma-oryzanol could decrease LDL-C levels and increase antioxidant capacity in hyperlipidemic subjects. Therefore, RBO consumption may reduce cardiovascular disease risk factors.