Rice Bran Oil Decreases Total and LDL Cholesterol in Humans: A Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials

Abstract

Cardiovascular disease (CVD) has become a concerning health problem because of its increasing prevalence. Vegetable oils such as rice bran oil may improve blood lipids, risk factors for CVD. We performed a systematic review and meta-analysis to identify and quantify the effects of rice bran oil on lipid profiles in humans. Literature databases (Pubmed, Scopus, Science Direct, Proquest, Ovid, and Google Scholar) were systematically searched until the end of November 2015, with no restrictions regarding study design, time, or language. The variables extracted for the meta-analysis included low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), total cholesterol (TC), triacylglycerol (TAG), VLDL-C, apoA, apoB, Lp(a), TC/HDL-C, and LDL-C/HDL-C. From 415 identified articles, 11 randomized controlled trials met the eligibility criteria and were included in our review. Rice bran oil consumption resulted in a significant decrease in concentrations of LDL-C (-6.91 mg/dl, 95% CI, -10.24 to -3.57; p<0.001) and TC (-12.65 mg/dl; 95% CI, -18.04 to -7.27; p<0.001). The increase in HDL-C levels were considerable only in men (6.65 mg/dl; 95% CI, 2.38-10.92; p=0.002). Results of our meta-analysis provided no evidence of a significant effekt of rice bran oil on other lipid profile components. In conclusion, consumption of rice bran oil can reduce LDL-C and TC concentrations, which may lead to prevention and control of CVD. It also has favorable effects on HDL-C concentrations in men. However, changes related to other lipid profile components are not considerable.

Effects of silymarin supplementation on blood lipids: A systematic review and meta‐analysis of clinical trials

“…Therefore, researchers have focused on alternative treatments including herbal medicine to manage dyslipidemia. Previous studies showed that some herbs or their products had favorable effects on lipid profile (Jolfaie, Rouhani, Surkan, Siassi, & Azadbakht, ; Pourmasoumi et al, ). Several herbs are considered as functional foods and rich in bioactive and lipid‐lowering agents including fiber, antioxidants, plant sterols, and stanols (Enkhmaa, Surampudi, Anuurad, & Berglund, ; Han et al, ; Rouhi‐Boroujeni, Rouhi‐Boroujeni, Heidarian, Mohammadizadeh, & Rafieian‐Kopaei, ).…”

The impact of pycnogenol supplementation on plasma lipids in humans: A systematic review and meta‐analysis of clinical trials

“…Although there are several phytochemicals with putative lipid‐ameliorating properties, the effectiveness of some herbs has been evaluated by randomized clinical trials and meta‐analyses supporting their effectiveness. Evidence showed that plant sterols and stanols, chitosan, probiotics, red yeast rice extract, garlic, ginger, and rice bran oil have favorable effects on blood lipids (Cicero et al, ; Jolfaie et al, ; Pirro et al, ; Pourmasoumi et al, ). However, lipid‐lowering properties of some components such as silymarin, resveratrol, and sour tea are not confirmed by present knowledge (Cicero et al, ).…”

“…In this regard, dyslipidemia, a set of abnormalities in lipid profile, is the major concern among CVDs patients (Kafeshani et al, ). Lifestyle modification is one of the main parts of current implemented therapies for dyslipidemia (Jolfaie, Rouhani, Surkan, Siassi, & Azadbakht, ). It is well known that lifestyle changes, in particular dietary management, are safer and more cost‐effective strategies than using medications (Sahebkar, ).…”

Dietary natural products as emerging lipoprotein(a)‐lowering agents

“…| LDL-C-lowering natural products with no effect on plasma Lp(a) Despite affecting LDL-C, some natural products do not change plasma Lp(a) levels. There are randomized controlled trials showing that certain natural products, including berberine (Cicero, Rovati, & Setnikar, 2007), brazil nut flour (Carvalho et al, 2015), ginger (Tabibi et al, 2016), garlic (Rysz-Gorzynska et al, 2016), tea catechin (Inami et al, 2007), olive oil (Chan, Demonty, Pelled, & Jones, 2007;Lichtenstein et al, 1993;Perona, Fitó, Covas, Garcia, & Ruiz-Gutierrez, 2011), onion (Ebrahimi-Mamaghani, Saghafi-Asl, Pirouzpanah, & Asghari-Jafarabadi, 2014), palm oil (Fattore, Bosetti, Brighenti, Agostoni, & Fattore, 2014), rice bran oil (Jolfaie, Rouhani, Surkan, Siassi, & Azadbakht, 2016), soy proteins and isoflavones (Hall et al, 2006;Merz-Demlow et al, 2000;Sacks et al, 2006;Turhan, Duvan, Bolkan, & Onaran, 2009), phytosterols (Garoufi et al, 2014;Nigon et al, 2001;Quílez et al, 2003), policosanol (Dulin, Hatcher, Sasser, & Barringer, 2006;Reiner, Tedeschi-Reiner, & Romić, 2005), vitamin C (Loots, Oosthuizen, Pieters, Spies, & Vorster, 2004), and B group of vitamins (Loots et al, 2004) Efficient Lp(a)-lowering therapy is achieved with an agent that can reduce Lp(a) levels to <30 mg/dl in patients with Lp(a) hyperlipoproteinemia(a) (Lp(a) ≥ 30 mg/dl). Niacin (from 1 to >3 g/day), which is generally considered as a strong Lp(a)-lowering agent, can reduce Lp (a) by 20-40%.…”