Modulation of the Hypolipidemic Effect of Fish Oils by Dietary Fiber in Rats: Studies with Rice and Wheat Bran

doi:10.1093/jn/120.4.325

The Journal of Nutrition

Volume 120, Issue 4, April 1990, Pages 325-330

https://doi.org/10.1093/jn/120.4.325 Get rights and content

ABSTRACT

Adult male rats were fed a purified diet containing rice bran or wheat bran with or without a marine fish oil to investigate the possible effects of such dietary combinations on lipid metabolism. Plasma and hepatic triacylglycerols and hepatic lipogenesis were lowered significantly by feeding fish oil with rice bran but not with wheat bran. Plasma cholesterol and hepatic cholesterol synthesis were significantly lower in animals fed fish oil with either bran. Liver microsomal free cholesterol was significantly lower in rats fed rice bran alone than in all other groups. Hepatic low density lipoprotein (LDL) receptor activity was significantly higher in the two groups fed rice bran than in the two groups fed wheat bran. Fish oil significantly decreased hepatic LDL receptor activity and increased hepatic high density lipoprotein (HDL) binding activity with wheat bran but had no significant effects on these parameters when added to the rice bran diet. However, when the data for all groups were pooled, there was a significant negative correlation between hepatic HDL binding activity and LDL receptor activity. Cecal volatile fatty acids were significantly higher in rats fed rice bran, were unaffected by adding fish oil to either bran diet and did not appear to mediate any of the effects of the brans and fish oil on plasma lipids and hepatic lipid metabolism. The combination of rice bran plus fish oil therefore appears to have more beneficial effects on lipid metabolism than wheat bran plus fish oil.

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Particle size of insoluble dietary fiber from rice bran affects its phenolic profile, bioaccessibility and functional properties
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Citation Excerpt :
Rice bran IDF has been shown to possess certain in vitro hypoglycemic and hypolipidemic properties, such as altering the conformation and inhibiting the activity of porcine pancreatic lipase, binding glucose and retarding α-amylase action (Qi et al., 2015, 2016). Rice bran IDF has been proved to have a hypocholesterolemic effect in rats (Topping et al., 1990) and certain beneficial effects in mildly hypercholesterolemic men (Kestin, Moss, Cliftonm, & Nestel, 1990). Furthermore, rice bran IDF was demonstrated to decrease both fasting and postprandial glucose levels in diabetic patients (Silva, de Oliveira, de Souza, & Silva, 2005).
Despite its various health benefits, rice bran insoluble dietary fiber (IDF) is not favored by people because of its rough texture and bad flavor. Therefore, many efforts have been made to modify IDF, including reducing its particle size. In the present study, the effects of superfine processing on the functional properties of rice bran IDF and its phenolic profiles and bioaccessibility were investigated. Superfine rice bran IDF powder exhibited a higher water holding capacity, swelling capacity and nitrite ion adsorption capacity, and a lower oil holding capacity than the other IDF powders. Moreover, the superfine rice bran IDF powder exhibited a higher extractability in both free and bound phenolics, higher phenolic bioaccessibility and antioxidant properties than its coarse counterpart. The extractable phenolic profile in superfine rice bran IDF was also different from those of other IDFs. These results suggest that superfine grinding can improve the functional properties of rice bran IDF and may benefit its application in functional foods.
Cellulosic fraction of rice bran fibre alters the conformation and inhibits the activity of porcine pancreatic lipase
2015, Journal of Functional Foods
Citation Excerpt :
These studies suggest that reducing intestinal absorption of fat and cholesterol is related to the nature of the fibre source (Cara et al., 1992). Rice bran has been shown to have a hypocholesterolaemic effect in rats (Topping et al., 1990) and some beneficial effects in mildly hypercholesterolaemic men (Kestin, Moss, Cliftonm, & Nestel, 1990), but has not been well studied as a potential PL inhibitor. Schneeman (1978) showed that rice bran reduced lipase activity, which was due in part to the binding of the enzyme to the fibre matrix.
A cellulosic rice bran insoluble dietary fibre (RBIDF) with different structures and physicochemical properties is shown to inhibit the activity of pancreatic lipase (PL) at different levels. The adsorption rate and saturation level to PL were greatest for RBIDF-2.0 (modified with 2.0% H₂SO₄ + 1.25% KOH), which had the highest specific surface area and oil holding capacity. The conformational deformation of unbound PL in the supernatant of PL-RBIDF confirmed by circular dichroism (CD) suggested that not only bound but also unbound PL activities were altered. Free energy calculations using data from fluorescence spectroscopy revealed that binding of PL to fibre depends primarily on electrostatic interactions, and the binding process is spontaneous and exothermic. This study indicates that dietary intake of cellulosic fractions of rice bran may be useful in reducing the bioavailability of dietary fat by altering the conformation and activity of PL that might be useful to control obesity.
Studies on functional and antioxidant property of dietary fibre extracted from defatted sesame husk, rice bran and flaxseed
2015, Bioactive Carbohydrates and Dietary Fibre
Citation Excerpt :
Dietary fibre is considered as a useful functional food, i.e., a food with health benefits, in many situations: its benefits for health maintenance and disease prevention have been well demonstrated and it is figured as a main component in medical nutrition therapy (Jalili, Wildman, & Mederon, 2000; Topping et al., 1990).
The study describes the preparation of functional food ingredient from by-product of vegetable oil industry. Accumulating evidence favours the view that increased intake of dietary fibre in an otherwise low fibre diet can have beneficial effects in both human and experimental animals. These benefits include prevention or alleviation of maladies such as cardiovascular disease, diabetes, diverticulosis and colon cancer. Studies have repeatedly shown that defatted oil bearing materials (such as, sesame husk, rice bran and flaxseed) give interesting health benefits. Compositional analysis reveals that sesame husk, rice bran and flaxseed consists of almost 68%, 27% and 39% dietary fibre respectively and has been reported to have positive health effects, such as in the form of a laxative and cholesterol-lowering agent. This suggests that sesame husk, rice bran and flaxseed are good fibre sources that can be added to various food products. This study examined the effectiveness of a dietary fibre preparation, derived from these sources, as a functional ingredient with potential of antioxidant activity. The observations established that dietary fibre from defatted flaxseed and rice bran had higher water binding, oil binding and emulsifying capacity compared to sesame husk dietary fibre. However, rice bran and sesame husk fibre were found to be less viscous than flaxseed fibre. Whereas in case of antioxidant activity rice bran fibre showed higher activity than flaxseed and sesame husk. The study confirms that the dietary fibre preparation from defatted sesame husk, rice bran and flaxseed have great potential in food applications, especially in development of functional foods.
Intake of brown rice lees reduces waist circumference and improves metabolic parameters in type 2 diabetes
2011, Nutrition Research
Citation Excerpt :
Rice bran is a unique cereal bran because of the type of fiber and the amount of fat it contains. Rice bran has a much higher fat content (20.1/100 g) than oat bran (6.8/100 g), corn bran (0.1/100 g), or wheat bran (5.7/100 g) [28]. We observed similar results in this study in that 100 g of the LB contained a much higher fat concentration (19.22 g) than that of mixed grains (0.86 g).
Intake of whole grains has been associated with lower risks of type 2 diabetes and cardiovascular disease. Brown rice is unrefined whole grain and is produced by removing the outermost layers containing the germ and bran, which are rich in nutrients including dietary fiber, vitamins, minerals, and other unmeasured dietary constituents. The lees of brown rice (LB) are by-products of its fermentation in the process of manufacturing takju, a Korean turbid rice wine. In this study, we hypothesized that intake of LB would reduce waist circumference, a strong risk factor for cardiovascular disease in type 2 diabetic patients. A randomized, double-blind, placebo-controlled study was scheduled for 12 weeks. Thirty subjects were randomly assigned to receive a supplement prepared from the LB or from a mixed-grain dietary product (MG). Body weight, waist circumference, body composition, lipid profiles, and other laboratory parameters were measured. The LB group showed greater reduction in waist circumference (LB: 87.9 ± 8.8 to 85.1 ± 9.0 cm; MG: 86.9 ± 8.8 to 86.0 ± 9.3 cm; P = .032). In addition, the consumption of LB resulted in a significantly greater decrease in the level of aspartate transaminase (LB: 25.4 ± 8.5 to 21.0 ± 5.1 IU/mL; MG: 22.5 ± 5.3 to 22.4 ± 5.7 IU/mL; P = .044) and alanine transaminase (LB: 28.6 ± 11.3 to 21.9 ± 8.2 IU/mL; MG: 24.4 ± 7.5 to 24.5 ± 9.9 IU/mL; P = .038). Consumption of the LB was associated with a decreased waist circumference in type 2 diabetic patients. Further study is required to evaluate the metabolic effect of the extract of the LB in type 2 diabetes.
Whole wheat flour exerts cholesterol-lowering in rats in its native form and after use in bread-making
2003, Food Chemistry
The ingestion of whole wheat flour (WWF) has been shown to exert lipid-lowering effects in rats but WWF is generally consumed after being processed (fermentation, starch gelatinization, heating). It remains to be assessed whether bread making has an influence on the potential lipid-lowering properties of flours. For this purpose, rats were fed semi-purified diets containing 70% WWF, or the same percentage of desiccated whole wheat bread (WWB) and the control group was fed with fibre-free purified starch diet. All the cereal diets showed a cholesterol-lowering effect in plasma and liver compared to control, but there was a more pronounced plasma triglyceride-lowering effect in rats fed WWB. In parallel, total steroids excretion was significantly enhanced (P <0.01) by the cereal diets, but to a greater extent by WWB. As a result, cholesterol absorption percentage was also markedly reduced in rats fed WWB diet (around 26%, compared to 38% for WWF and 52% for controls). WWF and WWB yielded butyric acid rich fermentations in the cecum, compared to the control diet, and WWB markedly enhanced propionic acid production compared to WWF. In conclusion, the baking process adds significantly to the hypolipemic effects observed previously with WWF, in spite of reduced specific viscosity.
Whole fat rice bran reduces the development of early aortic atherosclerosis in hypercholesterolemic hamsters compared with wheat bran
2002, Nutrition Research
In this study, Golden Syrian hamsters were fed a nonpurified hypercholesterolemic diet containing 10% coconut oil, 0.05% cholesterol and 20% wheat bran for 2 weeks (HCD) and based on mean plasma cholesterol levels were divided into four groups of 15. Hamsters were then fed the HCD or the HCD containing either 20% de-fatted rice bran (rice fiber), 20% heat-stabilized whole fat rice bran (WFRB), or 20% oat bran in place of wheat bran for 10 weeks. The rice fiber, WFRB, and oat bran diets significantly lowered plasma total cholesterol and very low- and low-density lipoprotein cholesterol levels compared to the wheat bran diet with no reductions in high-density lipoprotein cholesterol. Also, the WFRB diet significantly lowered plasma nonHDL-C levels compared to the rice fiber and oat bran diets. Aortic fatty streak formation was significantly reduced by WFRB diet compared to the wheat bran and rice fiber diets but not the oat bran. This study shows that whole fat rice bran reduces plasma cholesterol levels and the development of early aortic atherosclerosis in hypercholesterolemic hamsters similar to oat bran.

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Modulation of the Hypolipidemic Effect of Fish Oils by Dietary Fiber in Rats: Studies with Rice and Wheat Bran

ABSTRACT

J. Nutr.

Biochim. Biophys. Acta

Atherosclerosis

Atherosclerosis

Am. J. Clin. Nutr.

Am. J. Clin. Nutt.

Nutt. Res.

FEBS Lett.

J. Lipid Res.

J. Lipid Res.

FEBS Lett.

Metabolism