t Clinical Studies References
Rice bran is the outer grain hull of rice (Oryza sativa). It contains 21% fiber, 21% lipids, 13% amino acids and a wide variety of vitamins and minerals. Rice bran contains a relatively high percentage of oil compared with most other brans. Although whole rice bran seems to have some anti-hypercholesterolemic properties, rice bran oil is likely responsible for the most significant effect.
The oil contains beta sitosterol and other phytosterols that are used to reduce cholesterol absorption. It also contains alpha-linolenic acid, which might increase the concentration of fatty acids such as eicosapentaenoic and docosahexaenoic acids.
Other constituents of rice bran oil are gamma oryzanol and tocotrienols, which have been found in human studies to reduce total cholesterol and triglycerides. Oryzanol acts in three ways: 1) by increasing fecal bile acid excretion; 2) conversion of cholesterol to bile acids; 3) inhibition of cholesterol absorption. It also inhibits platelet aggregation and may decrease early atherosclerosis.
Oryzanol has also been used to treat nerve imbalance and disorders of menopause. The version of rice bran oil used in Xtend-Life's Cholest-Natural formula is an exceptionally pure oil from a US manufacturer with high levels of gamma oryzanol and tocotrienols.
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Published Clinical Studiescl top
1 Suppression of 7,12-dimethylbenz[alpha]anthracene-induced carcinogenesis and hypercholesterolaemia in rats by tocotrienol-rich fraction isolated from rice bran oil.
Iqbal J, Minhajuddin M, Beg ZH.
Anatomy and Cell Biology, Box No. 5, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY-11203, USA. jahangir.iqbal@downstate.edu
The anti-tumour and anti-cholesterol impacts of tocotrienol-rich fraction (TRF) were investigated in rats treated with the chemical carcinogen 7,12-dimethylbenz [alpha]anthracene (DMBA), which is known to induce mammary carcinogenesis and hypercholesterolaemia. DMBA administration to rats was associated with the appearance of multiple tumours on mammary glands after 6 months. Alkaline phosphatase (ALP) and glutathione-S-transferase (GST) are used as marker enzymes to monitor the severity of carcinogenesis. Although no tumours were visible on livers, hepatic ALP and GST activities of DMBA-treated rats were profoundly elevated in comparison to enzyme activities of normal control rats. Feeding of TRF (10 mg/kg body weight/day) for 6 months, isolated from rice bran oil (RBO), to DMBA-administered rats, reduced the severity and extent of neoplastic transformation in the mammary glands. Similarly, plasma and mammary ALP activities increased during carcinogenesis (95% and 43%, respectively), were significantly decreased in TRF-treated rats, whereas TRF mediated a further increase of 51% in hepatic ALP activity. TRF treatment to rats maintained low levels of GST activities in liver ( approximately 32%) and mammary glands ( approximately 21%), which is consistent with anti-carcinogenic properties of TRF. Administration of DMBA also caused a significant increase of 30% in plasma total cholesterol and 111% in LDL-cholesterol levels compared with normal control levels. Feeding of TRF to rats caused a significant decline of 30% in total cholesterol and 67% in LDL-cholesterol levels compared with the DMBA-administered rats. The experimental hypercholesterolaemia caused a significant increase in enzymatic activity (23%) and protein mass (28%) of hepatic 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase. Consistent with TRF-mediated reduction in plasma lipid levels, enzymatic activity and protein mass of HMG-CoA reductase was significantly reduced. These results indicate that TRF has potent anti-cancer and anti-cholesterol effects in rats.
PMID: 14639121 [PubMed]
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Novel tocotrienols of rice bran inhibit atherosclerotic lesions in C57BL/6 ApoE-deficient mice.2
Qureshi AA, Salser WA, Parmar R, Emeson EE.
Advanced Medical Research, Madison, WI 53719, USA. nqureshi@mhub.facstaff.wisc.edu
We are studying novel tocotrienols, which have a number of activities that might interfere with the formation of atherosclerotic plaques, including hypocholesterolemic, antioxidant, anti-inflammatory and antiproliferation effects. This study compared the effects of alpha-tocopherol, the tocotrienol-rich fraction (TRF(25)) and didesmethyl tocotrienol (d-P(25)-T3) of rice bran on the pathogenesis of atherosclerotic lesions in C57BL/6 apolipoprotein (apo)E-deficient (-/-) mice. These mice are an excellent model because they become hyperlipidemic even when they consume a low fat diet and they develop complex atherosclerotic lesions similar to those of humans. These compounds were also tested in wild-type C57BL/6 apoE (+/+) and (+/-) mice fed low or high fat diets. When a high fat diet was supplemented with alpha-tocopherol, TRF(25) or d-P(25)-T3 and fed to mice (+/+) for 24 wk, atherosclerotic lesion size was reduced 23% (P = 0.33), 36% (P = 0.14) and 57% (P < 0.02), respectively, and in mice (+/-) fed for 18 wk, lesions were reduced by 19% (P = 0.15), 28% (P < 0.01) and 33% (P < 0.005), respectively, compared with mice fed a control diet. A low fat diet did not cause atherosclerotic lesions in these mice. The low fat diet supplemented with TRF(25) or d-P(25)-T3 fed to apoE-deficient (-/-) mice for 14 wk decreased atherosclerotic lesion size by 42% (P < 0.04) and 47% (P < 0.01), respectively, whereas alpha-tocopherol supplementation resulted in only an 11% (P = 0.62) reduction. These results demonstrate the superior efficacy of tocotrienols compared with alpha-tocopherol. Although tocotrienols decreased serum triglycerides, total and LDL cholesterol levels, the decreases in atherosclerotic lesions seem to be due to the other activities. Serum tocol concentrations in various groups are also described. This is the first report of a significant reduction in the atherosclerotic lesion size in all three genotypes of apoE mice fed a novel tocotrienol (d-P(25)-T3) of rice bran. Dietary tocotrienol supplements may provide a unique approach to promoting cardiovascular health.
PMID: 11584079 [PubMed]
[Gamma-oryzanol: an important component in rice brain oil]3
Scavariello EM, Arellano DB.
Universidade Estadual de Campinas, Brasil.
Gamma-oryzanol, a mixture of ferulic acid esters of sterol and triterpene alcohols, it occurs in rice bran oil at a level of 1 to 2%, where it serves as natural antioxidant. Recent research has shown that gamma-Oryzanol can lower the cholesterol levels in the blood, lowering the risk of coronary heart disease, besides that, also has been used in Japan like natural antioxidant in foods, beverages and cosmetics. This review refers to aspects about gamma-Oryzanol, like its physiochemical properties, its presence in the rice bran oil, its antioxidant and hypocholesterolemic activity, as well as, identification, quantitation and extraction methods.
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Nutritional significance of rice bran oil.4
Raghuram TC, Rukmini C.
National Institute of Nutrition, Hyderabad.
India is the second largest producer of rice in the world and has the high potential to produce rice bran oil (RBO), a by-product of the rice milling industry. Since RBO is, an unconventional oil, the chemical composition, nutrient evaluation and toxicological safety were assessed. The fatty acid composition RBO is very close to that of groundnut oil (GNO). Though RBO has high unsaponifiable matter (4.2%), it is rich In minor constituents such as phytosterols, triterpene alcohols, tocopherols and tocotrienols. Experimental as well as human studies have demonstrated the hypolipidaemic effects of RBO. Further, It was established that minor constituents present in unsaponifiable fraction of RBO were responsible for its hypolipidaemic effects. Nutritional evaluation studies, carried out with 10 per cent RBO and 20 per cent protein, indicated that growth, feed efficiency and mineral balance were comparable to GNO-fed animals. Toxicological studies had shown that there were no abnormalities In animals fed either RBO or GNO. The reproductive performance was also found to be normal as compared with that of GNO-fed animals in all three generations. In addition, neither RBO nor the foods deepfried in it showed any mutagenicity as judged by Ames test. In view of its safety and hypolipidaemic activity, RBO could be considered as an alternative source of edible oil.
PMID: 8675245 [PubMed]
Nutritional and biochemical aspects of the hypolipidemic action of rice bran oil: a review.5
Rukmini C, Raghuram TC.
National Institute of Nutrition, Indian Council of Medical Research, Hyderabad.
In this paper, we review the effects of rice bran oil (RBO), an unconventional oil recently introduced onto the Indian market for human use. RBO contains oleic acid (38.4%), linoleic acid (34.4%), and linolenic acid (2.2%) as unsaturated fatty acids, and palmitic (21.5%) and stearic (2.9%) acids as saturated fatty acids. The unsaponifiable fraction (4.2%) has total tocopherols (81.3 mg%), gamma-oryzanol (1.6%), and squalene (320 mg%). Oryzanol is a mixture of ferulic acid esters of triterpene alcohols such as cycloartenol (CA) (106 mg%) and 24-methylene cycloartanol (494 mg%). Studies on experimental rats demonstrated a hypolipidemic effect of RBO. The unsaponifiable fraction of RBO lowers cholesterol levels. Feeding phytosterols, CA, and 24-methylene cycloartanol in amounts present in RBO to hypercholesterolemic rats for 8 weeks indicates that CA alone reduces cholesterol and triglyceride levels significantly. Endogenous sterol excretion increases in animals given CA. The accumulation of CA in the liver inhibits cholesterol esterase activity, which in turn leads to reduction in circulating cholesterol levels. CA is structurally similar to cholesterol and may compete with the binding sites of cholesterol and sequestrate cholesterol, which is metabolized to its derivatives. RBO, which is rich in tocopherols and tocotrienols, may improve oxidative stability. Tocotrienols inhibit HMG CoA reductase, resulting in hypocholesterolemia. The hypolipidemic effect of RBO has also been established in human subjects. Thus, RBO could be a suitable edible oil for patients with hyperlipidemia.
PMID: 1770191 [PubMed]
6 Rice bran oil lowers serum total and low density lipoprotein cholesterol and apo B levels in nonhuman primates.
Nicolosi RJ, Ausman LM, Hegsted DM.
Department of Clinical Sciences, University of Lowell, MA 01854.
The hypolipidemic response of rice bran oil (RBO) was investigated in nonhuman primates fed semi-purified diets containing blends of oils which included RBO at 0-35% Kcals as dietary fat. The studies demonstrated the following: (a) the degree of reduction of serum total cholesterol (TC) and low density lipoprotein cholesterol (LDLC) was highly correlated with initial serum cholesterol levels of the monkey on the stabilization diet; (b) the content of rice bran oil in the diet was the predominant factor influencing serum TC, LDLC and apoB causing up to a 40% reduction in LDLC without affecting high density lipoprotein cholesterol (HDLC) when RBO was the sole dietary oil fed; (c) the cholesterol-lowering capabilities of RBO were not explained by its fatty acid composition. These studies suggest that RBO may be an additional vegetable oil which lowers serum cholesterol levels by unique mechanisms which will require further study.
PMID: 1892480 [PubMed]
Influence of rice bran oil on serum lipid peroxides and lipids in human subjects.7
Rajnarayana K, Prabhakar MC, Krishna DR.
University College of Pharmaceutical Sciences, Kakatiya University, Warangal-506 009.
To study the effect of rice bran oil (RBO) on serum lipids and lipid peroxides in human volunteers. Nine healthy volunteers, aged between 42 to 57 years were given 75 ml of RBO thrice daily as the cooking medium with break fast, lunch and dinner for a period of 50 days. At the beginning and at the end of 50 days, 5 ml of blood were drawn from an ante cubital vein. Serum lipids and lipid peroxides levels were estimated from the blood sample. There was a significant decrease in the levels of lipid peroxides, triglycerides, LDL, VLDL, and total cholesterol in human volunteers who switched over to RBO. RBO has evidently antioxidant and antilipidemic activities in human subjects.
PMID: 11883150 [PubMed - indexed for MEDLINE]
Health benefits of rice bran oil.8
Sugano M, Koba K, Tsuji E.
Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Japan.
Although scientific evidence is relatively limited, rice bran oil (RBO) is tenaciously believed to be a healthy vegetable oil in Asian countries. It exerts hypocholesterolemic activity in relation to more commonly used vegetable oils and is characterized by a relatively high content of non-fatty acid components, some of which are known to have beneficial health effects. Components specific for RBO such as gamma-oryzanol and tocotrienols could participate in its hypocholesterolemic effects. In addition, blending RBO with safflower oil, but not with sunflower oil, may magnify the hypocholesterolemic efficacy. This observation is of particular interest with regard to dietary intervention with RBO. The possible mechanism underlying this effect may at least in part be related to the specific triglyceride structure of safflower oil, differing from that of sunflower oil.
PMID: 10625933 [PubMed - indexed for MEDLINE]
[Gamma-oryzanol: an important component in rice brain oil]9
PMID: 9754398 [PubMed - indexed for MEDLINE]
Rice bran oil and cholesterol metabolism.10
Sugano M, Tsuji E.
Laboratory of Food Science, Kyushu University School of Agriculture, Fuluoka, Japan.
A range of human and animal studies have shown that rice bran oil (RBO) is an edible oil of preference for improving serum cholesterol levels and lipoprotein profiles with similarity to the more commonly used vegetable oils such as corn oil and safflower oil. Of particular interest is the observation that blending RBO with safflower oil at a definite proportion (7:3, wt/wt) magnifies the hypocholesterolemic efficacy, compared with the effect of each oil alone. Although the mechanism underlying this effect is not apparent at present, the blending may have a practical significance. The blending effect was reproduced in rats fed a cholesterol-enriched diet, and there was also a decrease in liver cholesterol. The occurrence of peculiar components such as gamma-oryzanol and tocotrienols could be responsible for the hypocholesterolemic effect of RBO.
PMID: 9082039 [PubMed - indexed for MEDLINE]
11 Rice bran oil and gamma-oryzanol in the treatment of hyperlipoproteinaemias and other conditions.
Cicero AF, Gaddi A.