decreased triglycerides and around 48% decreased total cholesterol content compared to hyperlipidemic rats. Hypocholesterolemic impact of TRF may be due to the
repressive role of HMG-CoA reductase enzyme, a rate-limiting enzyme of the
mevalonate pathway, the metabolic pathway that produces cholesterol (Frank et al.
2012). Further, administration of 8 mg of TRF/kg/day showed highest antioxidant
effect. It may be due to the capacity of TRF to give electrons to free radicals
generated during the peroxidation of lipids. And thus, it was concluded that 8 mg
TRF/kg/day is appropriate to attain the desired antioxidant and hypocholesterolemic
effects (Minhajuddin et al. 2005).
Numerous studies conducted in humans with dyslipidemia have exhibited that
γ-oryzanol fraction of RBO in the diet improves the lipid profile, inflammatory and
oxidative stress levels (Nicolosi et al. 1991; Sharma and Rukmini 1986; Sasaki et al.
1990; Rong et al. 1997; Rajnarayana et al. 2001; Accinni et al. 2006). Nicolosi et al.
(1991) conducted a study on persistent schizophrenic patients having dyslipidemia;
they were provided with a diet containing γ-oryzanol at a concentration of 100 mg,
three times a day for 16 weeks. The authors reported significantly (P < 0.05)
decreased LDL-cholesterol (LDL-C) and total cholesterol (up to a 40% reduction),
whereas, no change in HDL cholesterol (HDL-C) was observed. Similarly, Sasaki
et al. (1990) also reported significantly (P < 0.05) decreased triglycerides, lipid
peroxides, VLDL-C, and LDL-C after consumption of RBO cooked food for
50 days. Furthermore, as reported by Accinni et al. (2006) dietary supplementation
of γ-oryzanol (40.2 mg) and niacin (18 mg), and vitamin E (4 mg) and PUFA
(660 mg EPA + 440 mg DHA), could significantly (P < 0.01) improve the lipid
profile, reactive oxygen species, and total antioxidant capacity of dyslipidemic
patients. Studies have reported oryzanol has a hypolipidemic effect possibly either
by increasing fecal excretion of cholesterol and its metabolites or by suppressing the
HMG CoA reductase activity (Wilson et al. 2007; Seetharamiah and Chandrasekhara
1990).
Further, non-saponifiable lipids of RBO, oryzanol, contributes to the cholesterollowering action of RBO associated with significant (P < 0.01) reductions in aortic
fatty streak formation (67%) (Rong et al. 1997).
Another study was performed in 14 human subjects who consumed RBO diet
(contributing one-third of total dietary fat) for 10 weeks substituting oil blends. (The
diet contained vegetable oil blends of canola, corn, peanut, olive, and palm oil and
butter having the similar fatty acid composition to that of RBO. Both diets were
designed to provide 37% of total energy as fat.) Significant decrease in total
cholesterol and decrease in LDL cholesterol by 7% (P < 0.0004) were found and
no changes appeared in the HDL levels during the evaluation on subjects taking
RBO diet. Further, an LDL constituent (apolipoprotein B) level was also found
lower (0.97 g/L) in the subjects taking RBO as a diet fat (Most et al. 2005). Kuriyan
et al. (2005) studied RBO and sunflower oil as cooking oils in 14 subjects of age
group 40–60 years with known hyperlipidemia, and their lipid profiles were evaluated for two periods each of 3 months including a washout period of 3 weeks. A
steady decline (P < 0.05) in serum triglycerides and total cholesterol (30% and 8%
respective reduction) were found during both the periods when RBO was used for
404
U. Yadav et al.
repressive role of HMG-CoA reductase enzyme, a rate-limiting enzyme of the
mevalonate pathway, the metabolic pathway that produces cholesterol (Frank et al.
2012). Further, administration of 8 mg of TRF/kg/day showed highest antioxidant
effect. It may be due to the capacity of TRF to give electrons to free radicals
generated during the peroxidation of lipids. And thus, it was concluded that 8 mg
TRF/kg/day is appropriate to attain the desired antioxidant and hypocholesterolemic
effects (Minhajuddin et al. 2005).
Numerous studies conducted in humans with dyslipidemia have exhibited that
γ-oryzanol fraction of RBO in the diet improves the lipid profile, inflammatory and
oxidative stress levels (Nicolosi et al. 1991; Sharma and Rukmini 1986; Sasaki et al.
1990; Rong et al. 1997; Rajnarayana et al. 2001; Accinni et al. 2006). Nicolosi et al.
(1991) conducted a study on persistent schizophrenic patients having dyslipidemia;
they were provided with a diet containing γ-oryzanol at a concentration of 100 mg,
three times a day for 16 weeks. The authors reported significantly (P < 0.05)
decreased LDL-cholesterol (LDL-C) and total cholesterol (up to a 40% reduction),
whereas, no change in HDL cholesterol (HDL-C) was observed. Similarly, Sasaki
et al. (1990) also reported significantly (P < 0.05) decreased triglycerides, lipid
peroxides, VLDL-C, and LDL-C after consumption of RBO cooked food for
50 days. Furthermore, as reported by Accinni et al. (2006) dietary supplementation
of γ-oryzanol (40.2 mg) and niacin (18 mg), and vitamin E (4 mg) and PUFA
(660 mg EPA + 440 mg DHA), could significantly (P < 0.01) improve the lipid
profile, reactive oxygen species, and total antioxidant capacity of dyslipidemic
patients. Studies have reported oryzanol has a hypolipidemic effect possibly either
by increasing fecal excretion of cholesterol and its metabolites or by suppressing the
HMG CoA reductase activity (Wilson et al. 2007; Seetharamiah and Chandrasekhara
1990).
Further, non-saponifiable lipids of RBO, oryzanol, contributes to the cholesterollowering action of RBO associated with significant (P < 0.01) reductions in aortic
fatty streak formation (67%) (Rong et al. 1997).
Another study was performed in 14 human subjects who consumed RBO diet
(contributing one-third of total dietary fat) for 10 weeks substituting oil blends. (The
diet contained vegetable oil blends of canola, corn, peanut, olive, and palm oil and
butter having the similar fatty acid composition to that of RBO. Both diets were
designed to provide 37% of total energy as fat.) Significant decrease in total
cholesterol and decrease in LDL cholesterol by 7% (P < 0.0004) were found and
no changes appeared in the HDL levels during the evaluation on subjects taking
RBO diet. Further, an LDL constituent (apolipoprotein B) level was also found
lower (0.97 g/L) in the subjects taking RBO as a diet fat (Most et al. 2005). Kuriyan
et al. (2005) studied RBO and sunflower oil as cooking oils in 14 subjects of age
group 40–60 years with known hyperlipidemia, and their lipid profiles were evaluated for two periods each of 3 months including a washout period of 3 weeks. A
steady decline (P < 0.05) in serum triglycerides and total cholesterol (30% and 8%
respective reduction) were found during both the periods when RBO was used for
404
U. Yadav et al.