|Year : 2014 | Volume
| Issue : 3 | Page : 159-163
Low density lipoprotein-cholesterol lowering activity of a blend of rice bran oil and safflower oil (7:3) in Indian patients with hyperlipidemia: a randomized, double blind, controlled, comparative, parallel group study
Nirmala N Rege1, J Lewis2, Swati Gupte2
1 Department of Pharmacology and Therapeutics, Seth GS Medical College and KEM Hospital, Parel, Mumbai, Maharashtra, India
2 Department of Research and Development, Marico Ltd., Kalina, Santacruz (East), Mumbai, Maharashtra, India
|Date of Submission||23-May-2014|
|Date of Decision||30-Jun-2014|
|Date of Acceptance||12-Jul-2014|
|Date of Web Publication||19-Sep-2014|
Nirmala N Rege
Department of Pharmacology and Therapeutics, Seth GS Medical College and KEM Hospital, Parel, Mumbai 400 012, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: Blends of rice bran oil (RBO) offer promise as functional foods to lower cholesterol. In Japan, a blend of 70% RBO and 30% safflower oil (KO) was shown to lower cholesterol in young healthy volunteers. However, this effect has not been demonstrated in hyperlipidemic individuals in the Indian population. Objective: We evaluated the effect of the blend on blood lipids in hyperlipidemic individuals for 12 weeks after 2 weeks stabilization period. Design: The study was a double blind, randomized, and controlled study. Thirty-five free-living individuals of either gender, aged 18-70 years completed this study. Assessment of subjects was carried out at baseline and weeks 0, 4, 8, and 12. Results: All 35 subjects completed the study. There was a significant reduction in serum cholesterol (21%, P < 0.001) at the end of 12 weeks in the experimental group. In the control group, there was a significant reduction till week 8 (17%, P < 0.001), followed by an increase at week 12. A similar trend was seen with serum low density lipoprotein (LDL). At week 12, LDL in the experimental group was significantly lower (P < 0.05) than LDL in the control group. Conclusions: Consumption of a diet enriched in the blended oil and meeting the recommended dietary guidelines resulted in an improved lipid profile. The blend can play an important role in the diet of people at risk of coronary heart disease.
Keywords: Blend, blood lipids, cholesterol, hyperlipidemia, rice bran oil, safflower oil
|How to cite this article:|
Rege NN, Lewis J, Gupte S. Low density lipoprotein-cholesterol lowering activity of a blend of rice bran oil and safflower oil (7:3) in Indian patients with hyperlipidemia: a randomized, double blind, controlled, comparative, parallel group study. J Obes Metab Res 2014;1:159-63
|How to cite this URL:|
Rege NN, Lewis J, Gupte S. Low density lipoprotein-cholesterol lowering activity of a blend of rice bran oil and safflower oil (7:3) in Indian patients with hyperlipidemia: a randomized, double blind, controlled, comparative, parallel group study. J Obes Metab Res [serial online] 2014 [cited 2020 Aug 9];1:159-63. Available from: http://www.jomrjournal.org/text.asp?2014/1/3/159/141145
| Introduction|| |
Evidence of a direct link between total fat and type of dietary fat intake and coronary heart disease (CHD) has led to the formulation of dietary guidelines for quantity and quality of fat intake for reducing risk of heart disease. The guidelines for Indians given by the Indian Council of Medical Research  are: Total fat should provide between 15% and 30% of total calories, the upper limit for saturated fatty acids (SFA) 8-10% of total calories, polyunsaturated fatty acids (PUFA) 5-8% of total calories, and the difference to be contributed by monounsaturated fatty acids (MUFA) Since no single edible oil provides the above ratio, using more than one type of oil is recommended to ensure optimal health benefits. It is also recommended that individuals with risk factors for atherosclerosis should limit intake of visible fats to 20 g/day. Given the fact that Indians have the highest prevalence of CHD among all ethnic groups in the world, choice of vegetable oil for cooking is important to lower the risk of CHD. A vegetable oil with a balanced fatty acid composition capable of normalizing the lipid profile can play an important role as a functional food in the diet of people at risk of CHD.
In Japan, a blend of 70% rice bran oil (RBO) and 30% safflower oil (KO) was shown to lower cholesterol in young healthy volunteers fed 60 g oil for 7 days. ,, However, this effect has not been demonstrated in hyperlipidemic individuals consuming less amount of oil as per the recommended guidelines. The present study was, therefore, planned to evaluate the effect of a blend of 70% RBO and 30% KO in free-living hyperlipidemic individuals following a reduced fat diet. Sunflower oil that is a high PUFA oil commonly used for cooking in India and hence, was used as a control.
| Subjects and methods|| |
The study was conducted after obtaining the institutional ethics committee permission in accordance with the Declaration of Helsinki. Free living, noninstitutionalized Indians of either gender between age group 18 and 70 years attending the cardiology outpatient clinic of KEM hospital and Seth GS medical college, and meeting the inclusion criteria of having serum cholesterol >200 mg% were included in the study post obtaining written informed consent. Subjects were excluded if they were pregnant; over 70 years or were morbidly obese body mass index (BMI) >30 kg/m 2 . They were also not selected if they had any liver or thyroid disorders, uncontrolled hypertension, congestive cardiac failure, acute myocardial infarction or were on lipid-lowering drugs, diuretics, or nonspecific beta blockers. Subjects with mild or moderate essential hypertension controlled on drug therapy devoid of any effect on lipid profile and or having well-controlled noninsulin dependent diabetes mellitus were included in the study.
After obtaining written informed consent, a general clinical examination was carried out and fasting (10-12 h) venous blood sample was collected for hemogram, lipid profile, routine liver and renal function test, and plasma glucose levels. Body weight, height, waist, and hip circumference were recorded. The subjects were then referred to a dietician for a detailed history of regular food and oil consumption. A 24 h dietary recall was collected from the subject at baseline and at the end of the study. A complete dietary history which included the consumption of vegetarian or nonvegetarian diet; frequency of consumption of meat, fish, poultry, eggs, consumption of fried, and high fat foods like dry or fresh coconut, groundnut, and other oil seeds-oil intake was obtained from the subject at this time. Standardized bowls were used to assess the amount of food consumed. Clay models of dough were used to assess the amount of flour used for making chappati. The average intake of major food groups, namely cereals, pulses, meat, milk, vegetables, fruits, and oil was calculated. The subjects were advised to follow a low-fat diet, avoid fried, and cholesterol-rich, and to avoid eating food not cooked at home.
After 2 weeks of stabilization on the low-fat diet, fasting blood samples were collected for estimating lipid profiles, and the subjects were allotted to either treatment group randomly. One group received a blend of 70% RBO and 30% KO while the other group received sunflower oil. The oils were designated as A and B, and the study was a double-blind study the codes were revealed after the statistical analysis was completed. The subjects were advised to use the respective oil for cooking and follow their usual meal pattern while maintaining the advised dietary restrictions. The amount of oil permitted/person/month was about 500 ml and the intake was continued for a period of 12 weeks. Thus, the total study duration was 14 weeks. Clinical assessment of subjects was carried out at baseline (week 2) and weeks 0, 2, 4, 8, 12 of the intervention, and blood was collected for analysis at weeks 0, 2, 4, 8 and 12.
Serum was separated by centrifuging at 543 × g for 10 min, within 30 min of blood collection and used for analysis the same day. Excess serum was stored at –20°C. Cholesterol, triacylglycerols, glucose, total protein, serum glutamic-pyruvic transaminase, serum glutamic oxaloacetic transaminase, creatine, alkaline phosphatase, bilirubin, and blood urea nitrogen were estimated Using kits from Trans Asia Bio Medicals Ltd. and Erba Chem 5 semi auto analyzer (India). Low density lipoprotein (LDL) was calculated using the Friedewald formula. Hemoglobin was estimated by the cyanmethemoglobin method. White blood cells were counted using a hemocytometer and erythrocyte sedimentation rate was estimated by Wintrobe's method.
Results are expressed as mean ± SD differences between groups were examined by t-tests (two-tailed) and comparisons within the groups by paired t-tests. Significance was set at P < 0.05.
| Results|| |
All 35 recruited subjects completed the study. The age range was between 25 and 65 years, and the routine organ-function test results were within normal range. The baseline data is presented in [Table 1]. All parameters were comparable between the two groups and did not show significant difference.
The lipid profile at baseline and after 2 weeks stabilization on the recommended diet is shown in [Table 2]. There was no significant difference in the lipid profile between the two groups at baseline. After 2 weeks, triacylglycerols values were lower than baseline in both groups, while LDL value was lower in the experimental group. However, there were no significant differences between and within the two groups.
|Table 2: Lipid profile of patients at baseline and 2 weeks post-stabilization period |
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The changes in blood lipids from start of treatment (week 0) to the end of treatment (week 12) are shown in [Table 3]. In the experimental group, there was a significant reduction till week 8, after which there was an increase at week 12. There was no significant difference in cholesterol values between the two groups at any time point in the study. However, in the experimental group, a significant drop of 22% was seen from baseline. A similar trend was seen with serum LDL. However, LDL values in the experimental group were significantly lower (P < 0.0.5) than LDL values in the control group at week 12. In fact, the LDL cholesterol levels dropped by 35% from baseline in the experimental group as compared to the 12% drop seen in the control group [Figure 1]. High-density lipoprotein (HDL) values increased in the experimental group, although this increase was not statistically significant. The HDL values were comparable between the two groups at all-time points and did not show any statistical significance [Figure 2]. Serum cholesterol showed significant reductions [Figure 3] and serum to HDL cholesterol ratio was significantly lowered in both groups. There was no significant change in serum triacylglycerols from baseline values [Figure 4] in both groups, and values between the groups were comparable throughout the treatment period and did not show any statistically significant difference.
|Figure 1. Comparison of low density lipoprotein cholesterol levels in two groups (mg %) (**P < 0.01, Student's paired t-test versus week 0 value, ***P < 0.001, Student's paired t-test vs. week 0 value, #P < 0.05, Student's unpaired t-test vs. corresponding Group B value|
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|Figure 2. Comparison of high density lipoprotein cholesterol levels in two groups (mg %). (*P < 0.05, Student's paired t-test vs. week 0 value, **P < 0.01, Student's paired t-test vs. week 0 value)|
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|Figur 3. Comparison of serum cholesterol levels in two groups (mg%). (**P < 0.01, Student's paired t-test versus week 0 value, ***P < 0.001, Student's paired t-test vs. week 0 value)|
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There was a significant weight reduction, which was reflected in BMI in subjects in both groups at the end of the treatment period. There was no significant difference in weight and BMI between the groups.
| Discussion|| |
The study was designed to evaluate the effect of a blend of 70% RBO and 30% KO on lipid profile of individuals with mild to moderate hypercholesterolemia and/or hypertriglyceridemia compared with sunflower oil as a control within the context of the dietary guidelines for Indians. In our study, each subject was permitted ~15 g of the oil per day. The data indicate that use of this blended oil for cooking results in a significant reduction in serum cholesterol and LDL cholesterol along with a favorable response in HDL cholesterol in free-living subjects.
Similar results were reported in studies carried by Suzuki and Oshima , and Tsuji et.al.  in Japan. In one of the studies, volunteers were fed 60 g of blended oil for 7 days. This finding was repeatedly confirmed by the authors, and the blended oil was commercially distributed in Japan. Interestingly, in the study, the blend of RBO and sunflower oil did not show any additional effects.  Hence, it could be hypothesized that the RBO and KO blend has certain synergistic effect.
Another study on rats that were fed the blended oil along with either high cholesterol or cholesterol free diet for a period of 28 days showed significantly lower serum cholesterol, triacylglycerols, LDL cholesterol and increased HDL cholesterol. Liver serum cholesterol and triacylglycerols were also reduced. Fecal excretion of neutral sterols and bile acids was increased with the use of the blend. 
The cholesterol lowering effect of RBO has been demonstrated in humans and animals. ,,,,,,, The hypocholesterolemic action of RBO has been attributed to tocotrienols and oryzanol which form the nonglyceride portion of RBO. Tocotrienols exert their cholesterol-lowering effect by inhibiting methylglutaryl coenzyme A reductase activity in the liver, while oryzanol may exert its effect by inhibiting cholesterol absorption and increasing fecal excretion of bile acids. ,,,, The cholesterol lowering effect of PUFA is well known.
It is known that dietary fatty acids in the sn-2 position are preferentially absorbed as monoacylglycerols.  Fatty acids in the sn-2 position are also preferentially transported to the liver instead of the extrahepatic tissues and thereby affect LDL metabolism. Mu and Hoy estimate an approximate 75% conservation of fatty acids in the sn-2 position, despite acyl migration to the sn-1/3 positions.  Also, it is known that if the composition of a particular fatty acid is higher among the three fatty acids-chances of that getting incorporated in sn-2 position is high.  This probably could be the reason for higher cholesterol reduction seen with safflower oil than sunflower oil, since as safflower oil has higher PUFA levels.
Based on the study observations, it can be proposed that blending RBO and KO in 70:30 ratio results in a synergy between the high linoleic acid from safflower oil and tocotrienols and oryzanol from RBO.
The effect of sunflower oil on lipids was also expected given to the high-PUFA content. However, the increase in serum cholesterol and LDL cholesterol from week 8 to 12 cannot be explained.
The work of Keys and Hegsted , showed that substituting saturated fats with PUFA lowered cholesterol and the general dietary advice was to use oils like safflower or sunflower oil.
However, subsequent research has shown that the relationship between dietary fats and lipoproteins is more complex. It is now felt that high levels of n-6 PUFA in the diet is not desirable since at high levels n-6 PUFA lower HDL cholesterol. High intakes of linoleic acid also produce an imbalance between n-6 and n-3 PUFA. Therefore, to ensure optimal health benefits, the use of blended oils instead of a single oil is recommended.  Recent RDA for Indians developed by National Institute of Nutrition, India recommends that "one should use a correct combination/blend of 2 or more vegetable oils to achieve an intake of all kinds of fatty acids". 
A moderate level of PUFA is achieved by blending 70% RBO and 30% KO as shown in [Table 4], which falls within the recommended level for PUFA intake. This oil also offers the added benefit of the unsaponifiable material from RBO.
| Conclusion|| |
Consumption of a diet that meets the recommended dietary guidelines and enriched in the blended oil will result in an improved lipid profile, thus, reducing the risk of CHD.
| Acknowledgments|| |
The authors like to mention that the oil blend used in the study was provided by Marico Ltd., India. We like to thank Mr. Kailas Gandewar for his statistical expertise. We also like to express our gratitude to Dr. Sudhakar Mhaskar and Mr. Anand Dhodapkar for providing guidance for this project.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]