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Linoleic acid-rich fats reduce atherosclerosis development beyond its oxidative and inflammatory stress-increasing effect in apolipoprotein E-deficient mice in comparison with saturated fatty acid-rich fats.
Sato M, Shibata K, Nomura R, Kawamoto D, Nagamine R, Imaizumi K.
Laboratory of Nutrition Chemistry, Division of Bioresource and Bioenvironmental Sciences, Graduate School, Kyushu University, Fukuoka 812-8581, Japan.
The relative benefit of replacing saturated fatty acid with linoleic acids is still being debated because a linoleic acid-enriched diet increases oxidative and inflammatory stresses, although it is associated with a reduction in serum cholesterol levels. The present study was conducted to evaluate the effect of dietary supplementation of linoleic acid-rich (HL) fat, compared with a saturated fatty acid-rich (SF) fat on atherosclerotic lesion areas, serum and liver cholesterol levels, oxidative stress (urinary isoprostanes and serum malondialdehayde) and inflammatory stress (expression of aortic monocyte chemoattractant protein-1; MCP-1) in apo E-deficient mice. Male and female apo E-deficient mice (8 weeks old; seven to eight per group) were fed an AIN-76-based diet containing SF fat (50 g palm oil and 50 g lard/kg) or HL fat (100 g high-linoleic safflower-seed oil/kg) for 9 weeks. Compared with the SF diet, the HL diet lowered atherosclerosis (P<0.05). It reduced serum total cholesterol levels (P<0.05), increased HDL-cholesterol levels (P<0.05) and lowered liver esterified cholesterol levels (P<0.01). The HL diet-fed mice showed increased expression of MCP-1 mRNA (P<0.05), serum levels of malondialdehayde (P<0.05) and urinary excretion of 2,3-dinor-5,6-dihydro-8-iso-prostaglandin F2alpha; P<0.05). These results suggest that having biomarkers in vivo for oxidative stress and inflammatory status of endothelial cells does not necessarily indicate predisposition to an increased lesion area in the aortic root in apo E-deficient mice fed an HL or SF diet.
PMID: 16351765 [PubMed - indexed for MEDLINE]
Different palm oil preparations reduce plasma cholesterol concentrations and aortic cholesterol accumulation compared to coconut oil in hypercholesterolemic hamsters.
Wilson TA, Nicolosi RJ, Kotyla T, Sundram K, Kritchevsky D.
Department of Health and Clinical Sciences, Center for Health and Disease Research, University of Massachusetts Lowell, Lowell, MA 01854-5125, USA.
Several studies have reported on the effect of refined, bleached and deodorized palm oil (RBD-PO) incorporation into the diet on blood cholesterol concentrations and on the development of atherosclerosis. However, very little work has been reported on the influence of red palm oil (RPO), which is higher in carotenoid and tocopherol content than RBD-PO. Thus, we studied the influence of RPO, RBD-PO and a RBD-PO plus red palm oil extract (reconstituted RBD-PO) on plasma cholesterol concentrations and aortic accumulation vs. hamsters fed coconut oil. Forty-eight F1B Golden Syrian hamsters (Mesocricetus auratus) (BioBreeders, Watertown, MA) were group housed (three/cage) in hanging polystyrene cages with bedding in an air-conditioned facility maintained on a 12-h light/dark cycle. The hamsters were fed a chow-based hypercholesterolemic diet (HCD) containing 10% coconut oil and 0.1% cholesterol for 2 weeks at which time they were bled after an overnight fast and segregated into four groups of 12 with similar plasma cholesterol concentrations. Group 1 continued on the HCD, Group 2 was fed the HCD containing 10% RPO in place of coconut oil, Group 3 was fed the HCD containing 10% RBD-PO in place of coconut oil and Group 4 was fed the HCD with 10% reconstituted RBD-PO for an additional 10 weeks. Plasma total cholesterol (TC) and non-high-density lipoprotein-cholesterol (HDL-C) (very low- and low-density lipoprotein) concentrations were significantly lower in the hamsters fed the RPO (-42% and -48%), RBD-PO (-32% and -36%) and the reconstituted RBD-PO (-37% and -41%) compared to the coconut oil-fed hamsters. Plasma HDL-C concentrations were significantly higher by 14% and 31% in hamsters fed the RBD-PO and RPO compared to the coconut oil-fed hamsters. Plasma triglyceride (TG) concentrations were significantly lower in hamsters fed RBD-PO (-32%) and the reconstituted RBD-PO (-31%) compared to the coconut oil-fed hamsters. The plasma gamma-tocopherol concentrations were higher in the coconut oil-fed hamsters compared to the hamsters fed the RPO (60%), RBD-PO (42%) and the reconstituted RBD-PO (49%), while for plasma alpha-tocopherol concentrations, the coconut oil-fed hamsters were significantly higher than only the RPO-fed hamsters (21%). The coconut oil-fed hamsters also had significantly higher plasma lipid hydroperoxide concentrations compared to RBD-PO (112%) and the reconstituted RBD-PO (485%). The hamsters fed the coconut oil diet excreted significantly more fecal total neutral sterols and cholesterol compared to the hamsters fed the RBD-PO (158% and 167%, respectively). The coconut oil-fed hamsters had significantly higher levels of aortic total, free and esterified cholesterol compared to the hamsters fed the RPO (74%, 50% and 225%, respectively), RBD-PO (57%, 48% and 92%, respectively) and the reconstituted RBD-PO (111%, 94% and 94%, respectively). Also, aortic free/ester cholesterol ratio in the aortas of hamsters fed RPO was significantly higher than in those fed the coconut oil (124%). In conclusion, hamsters fed the three palm oil preparations had lower plasma TC and non-HDL-C and higher HDL-C concentrations while accumulating less aortic cholesterol concentrations compared to hamsters fed coconut oil.
PMID: 16081272 [PubMed - indexed for MEDLINE]
Palm fruit chemistry and nutrition.
Sundram K, Sambanthamurthi R, Tan YA.
Malaysian Palm Oil Board, P.O. Box 10620, 50720 Kuala Lumpur, Malaysia. kalyana@mpob.gov.my
The palm fruit (Elaies guineensis) yields palm oil, a palmitic-oleic rich semi solid fat and the fat-soluble minor components, vitamin E (tocopherols, tocotrienols), carotenoids and phytosterols. A recent innovation has led to the recovery and concentration of water-soluble antioxidants from palm oil milling waste, characterized by its high content of phenolic acids and flavonoids. These natural ingredients pose both challenges and opportunities for the food and nutraceutical industries. Palm oil's rich content of saturated and monounsaturated fatty acids has actually been turned into an asset in view of current dietary recommendations aimed at zero trans content in solid fats such as margarine, shortenings and frying fats. Using palm oil in combination with other oils and fats facilitates the development of a new generation of fat products that can be tailored to meet most current dietary recommendations. The wide range of natural palm oil fractions, differing in their physico-chemical characteristics, the most notable of which is the carotenoid-rich red palm oil further assists this. Palm vitamin E (30% tocopherols, 70% tocotrienols) has been extensively researched for its nutritional and health properties, including antioxidant activities, cholesterol lowering, anti-cancer effects and protection against atherosclerosis. These are attributed largely to its tocotrienol content. A relatively new output from the oil palm fruit is the water-soluble phenolic-flavonoid-rich antioxidant complex. This has potent antioxidant properties coupled with beneficial effects against skin, breast and other cancers. Enabled by its water solubility, this is currently being tested for use as nutraceuticals and in cosmetics with potential benefits against skin aging. A further challenge would be to package all these palm ingredients into a single functional food for better nutrition and health.
Publication Types:
PMID: 14506001 [PubMed - indexed for MEDLINE]
Induction of fatal inflammation in LDL receptor and ApoA-I double-knockout mice fed dietary fat and cholesterol.
Zabalawi M, Bhat S, Loughlin T, Thomas MJ, Alexander E, Cline M, Bullock B, Willingham M, Sorci-Thomas MG.
Department of Pathology, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
Atherogenic response to dietary fat and cholesterol challenge was evaluated in mice lacking both the LDL receptor (LDLr(-/-)) and apoA-I (apoA-I(-/-)) gene, LDLr(-/-)/apoA-I(-/-) or double-knockout mice. Gender- and age-matched LDLr(-/-)/apoA-I(-/-) mice were fed a diet consisting of 0.1% cholesterol and 10% palm oil for 16 weeks and compared to LDLr(-/-) mice or single-knockout mice. The LDLr(-/-) mice showed a 6- to 7-fold increase in total plasma cholesterol (TPC) compared to their chow-fed mice counterparts, while LDLr(-/-)/apoA-I(-/-) mice showed only a 2- to 3-fold increase in TPC compared to their chow-fed controls. This differential response to the atherogenic diet was unanticipated, since chow-fed LDLr(-/-) and LDLr(-/-)/apoA-I(-/-) mice began the study with similar LDL levels and differed primarily in their HDL concentration. The 6-fold diet-induced increase in TPC observed in the LDLr(-/-) mice occurred mainly in VLDL/LDL and not in HDL. Mid-study plasma samples taken after 8 weeks of diet feeding showed that LDLr(-/-) mice had TPC concentrations approximately 60% of their 16-week level, while the LDLr(-/-)/apoA-I(-/-) mice had reached 100% of their 16-week TPC concentration after only 8 weeks of diet. Male LDLr(-/-) mice showed similar aortic cholesterol levels to male LDLr(-/-)/apoA-I(-/-) mice despite a 4-fold higher VLDL/LDL concentration in the LDLr(-/-) mice. A direct comparison of the severity of aortic atherosclerosis between female LDLr(-/-) and LDLr(-/-)/apoA-I(-/-) mice was compromised due to the loss of female LDLr(-/-)/apoA-I(-/-) mice between 10 and 14 weeks into the study. Diet-fed female and, with time, male LDLr(-/-)/apoA-I(-/-) mice suffered from severe ulcerated cutaneous xanthomatosis. This condition, combined with a complete depletion of adrenal cholesterol, manifested in fatal wasting of the affected mice. In conclusion, LDLr(-/-) and LDLr(-/-)/apoA-I(-/-) mice showed dramatic TPC differences in response to dietary fat and cholesterol challenge, while despite these differences both genotypes accumulated similar levels of aortic cholesterol.
PMID: 12937162 [PubMed - indexed for MEDLINE]
Palm oil: biochemical, physiological, nutritional, hematological, and toxicological aspects: a review.
Edem DO.
Department of Chemistry and Biochemistry, University of Uyo, Uyo, Akwa Ibom State, Nigeria.
The link between dietary fats and cardiovascular diseases has necessitated a growing research interest in palm oil, the second largest consumed vegetable oil in the world. Palm oil, obtained from a tropical plant, Elaeis guineensis contains 50% saturated fatty acids, yet it does not promote atherosclerosis and arterial thrombosis. The saturated fatty acid to unsaturated fatty acid ratio of palm oil is close to unity and it contains a high amount of the antioxidants, beta-carotene, and vitamin E. Although palm oil-based diets induce a higher blood cholesterol level than do corn, soybean, safflower seed, and sunflower oils, the consumption of palm oil causes the endogenous cholesterol level to drop. This phenomenon seems to arise from the presence of the tocotrienols and the peculiar isomeric position of its fatty acids. The benefits of palm oil to health include reduction in risk of arterial thrombosis and atherosclerosis, inhibition of endogenous cholesterol biosynthesis, platelet aggregation, and reduction in blood pressure. Palm oil has been used in the fresh state and/or at various levels of oxidation. Oxidation is a result of processing the oil for various culinary purposes. However, a considerable amount of the commonly used palm oil is in the oxidized state, which poses potential dangers to the biochemical and physiological functions of the body. Unlike fresh palm oil, oxidized palm oil induces an adverse lipid profile, reproductive toxicity and toxicity of the kidney, lung, liver, and heart. This may be as a result of the generation of toxicants brought on by oxidation. In contrast to oxidized palm oil, red or refined palm oil at moderate levels in the diet of experimental animals promotes efficient utilization of nutrients, favorable body weight gains, induction of hepatic drug metabolizing enzymes, adequate hemoglobinization of red cells and improvement of immune function. Howerer, high palm oil levels in the diet induce toxicity to the liver as shown by loss of cellular radial architecture and cell size reductions which are corroborated by alanine transaminase to asparate transaminase ratios which are higher than unity. The consumtion of moderate amounts of palm oil and reduction in the level of oxidation may reduce the health risk believed to be associated with the consumption of palm oil. Red palm oil, by virtue of its beta-carotene content, may protect against vitamin A deficiency and certain forms of cancer.
Publication Types:
PMID: 12602939 [PubMed - indexed for MEDLINE]
Red palm oil in experimental atherosclerosis.
Kritchevsky D, Tepper SA, Czarnecki SK, Sundram K.
The Wistar Institute, Philadelphia, PA 19104, USA. kritchevsky@wistar.upenn.edu
Publication Types:
PMID: 12492630 [PubMed - indexed for MEDLINE]
Effect of palm olein oil in a moderate-fat diet on plasma lipoprotein profile and aortic atherosclerosis in non-human primates.
van Jaarsveld PJ, Smuts CM, Benade AS.
Nutritional Intervention Research Unit, Medical Research Council, Parow, South Africa. paul.van.jaarsveld@mrc.ac.za
Several studies have reported on the effect of palm olein oil (PO; palmitic acid content approximately 38%) incorporation into the diet on blood cholesterol concentration. Information on the effect of PO on atherosclerosis is, however, lacking. In vervet monkeys (Cercopithecus aethiops), low-density lipoprotein cholesterol (LDL-C) concen-trations can be modulated by the type and amount of fat in the diet. The vervet is a proven model for both the type and composition of human atherosclerotic lesions. The aim of this study was to determine the effect of PO in a moderate-fat moderate-cholesterol diet (MFD) on plasma lipoproteins and the progression of atherosclerosis in a non-human primate model after 25.5 months of dietary exposure. Thirty adult male vervets, never exposed to a Western-type atherogenic diet, were stabilised on a MFD (28%E fat; 26 mg cholesterol/1000 kJ) with a polyunsaturated to saturated fatty acid (P/S) ratio of 0.4 for six weeks. Baseline LDL-C, high-density lipoprotein (HDL)-C and bodyweight were used to stratify the vervets into three comparable groups of 10 each. One group continued with the MFD in which 11.0%E was derived from lard (AF). In the other two groups, the AF was substituted isocalorically with either sunflower oil (SO) or PO. Plasma lipids were measured at 6-monthly intervals and atherosclerosis was assessed in the aorta and in five peripheral arteries after 25.5 months of dietary exposure. The frequency of atherosclerosis in peripheral arteries and aortas was low. PO, relative to SO and AF, significantly reduced the risk for developing early lesions in peripheral arteries (P = 0.0277 and P = 0.0038, respectively) and, relative to AF, in aortas (P = 0.0335). The cholesterolaemic effect of MFD-PO was not significantly different from MFD-SO and MFD-AF. However, at 24 months the plasma total cholesterol concentration with MFD-AF was significantly higher than with MFD-SO (P = 0.0256). It is confirmed that a MFD with PO is no different from AF or SO in its cholesterolaemic effect. The anti-atherogenic efficacy of a MFD with PO, relative to SO and AF, was demonstrated in a non-human primate model of atherogenesis.
PMID: 12492629 [PubMed - indexed for MEDLINE]
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Transgenic overexpression of human lecithin: cholesterol acyltransferase (LCAT) in mice does not increase aortic cholesterol deposition.
Furbee JW Jr, Parks JS.
Department of Pathology, Section on Comparative Medicine, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1040, USA.
Results from several atherosclerosis studies using morphometric procedures have proven controversial with regard to whether over-expression of human LCAT in transgenic (Tg) mice is atherogenic. The purpose of the present study was to determine the effect of 10-fold over-expression of human LCAT on aortic free and esterified cholesterol (EC) deposition as well as plasma lipoprotein cholesteryl ester (CE) fatty acid composition in mice fed an atherogenic diet containing cholic acid. C57Bl/6 (control) and human LCAT-Tg mice were fed chow or an atherogenic diet (15% of calories from palm oil, 1.0% cholesterol and 0.5% cholic acid) for 24 weeks before measurement of aortic cholesterol content. Compared with the chow diet, control and LCAT-Tg mice fed the atherogenic diet had a 2-fold increase in plasma total, free and EC, a 7-fold increase in plasma apoB lipoprotein cholesterol, and a 40-50-fold increase in hepatic cholesterol content. The aortic EC content was increased in control (0.7 vs. 1.2 mg/g protein) and LCAT-Tg (0.3 vs. 1.5 mg/g protein) mice fed the atherogenic diet compared with those consuming the chow diet; however, there was no difference in aortic free (14.4+/-6.8 vs. 18.5+/-7.7 mg/g protein) or esterified (1.2+/-1.0 vs. 1.5+/-1.2 mg/g protein) cholesterol content between atherogenic diet-fed control and LCAT-Tg mice, respectively. LCAT-Tg mice fed the atherogenic diet had a 2-fold increase in the ratio of saturated+monounsaturated to polyunsaturated CE species in plasma apoB lipoproteins compared with control mice (9.4+/-2.4 vs. 4.9+/-0.7). We conclude that over-expression of human LCAT in Tg mice fed an atherogenic diet containing cholic acid does not result in increased aortic cholesterol deposition compared with control mice, even though the CE fatty acid saturation index of plasma apoB lipoproteins was doubled.
PMID: 12208474 [PubMed - indexed for MEDLINE]
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Effect of palm oil on oxidative stress-induced hypertension in Sprague-Dawley rats.
Ganafa AA, Socci RR, Eatman D, Silvestrov N, Abukhalaf IK, Bayorh MA.
Department of Pharmacology & Toxicology, Morehouse School of Medicine, Atlanta, Georgia 30310-1495, USA.
BACKGROUND: Oxidative stress, associated with increased plasma isoprostane (ISO) and reductions in plasma glutathione (GSH), has been shown to cause severe hypertension in normal rats. Palm oil (PO), with an unsaturated-to-saturated fatty acid ratio close to one and rich in antioxidant vitamins, has been investigated for its beneficial effects on arterial thrombosis and atherosclerosis. In this study, the effect of PO on oxidative stress induced by inhibition of GSH synthesis (using buthionine sulfoximine [BSO]) was examined. METHODS: Sprague-Dawley rats were separated into two groups and received either natural vitamin-rich PO (Carotino, 5 g/kg daily) or water by gavage. After 4 weeks, they were further divided between receiving either BSO (30 mmol/L/day in the drinking water) or drug-free water for an additional week. Mean arterial pressure (MAP), heart rate (HR), and body weight (BW) were measured before and weekly during the experiment. The levels of plasma ISO, nitric oxide (NO), prostacyclin (PGI2), and thromboxane A2 (TXA2) were determined by enzyme immunoassay, and plasma, heart, and kidney GSH by high-performance liquid chromatography. RESULTS: The PO reduced the age-dependent increase in MAP, and the pressor response to BSO, without changing the HR or BW compared to the BSO and control groups. It also elevated PGI2, NO, and aortic cGMP, but decreased TXA2 and aortic cAMP. In addition, the BSO-induced increase in ISO and TXA2, and the reduction in kidney GSH were attenuated by PO. However, the PO effect on NO, PGI2, cGMP, and TXA2 was partly counteracted by BSO. CONCLUSIONS: Palm oil reduces BSO-induced oxidative stress and attenuates hypertension by mechanisms involving changes in endothelium-derived factors.
PMID: 12160196 [PubMed - indexed for MEDLINE]
Lecithin:cholesterol acyltransferase deficiency increases atherosclerosis in the low density lipoprotein receptor and apolipoprotein E knockout mice.
Furbee JW Jr, Sawyer JK, Parks JS.
Department of Pathology, Section on Comparative Medicine, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, North Carolina 27157-1040, USA.
The purpose of the present study was to test the hypothesis that lecithin:cholesterol acyltransferase (LCAT) deficiency would accelerate atherosclerosis development in low density lipoprotein (LDL) receptor (LDLr-/-) and apoE (apoE-/-) knockout mice. After 16 weeks of atherogenic diet (0.1% cholesterol, 10% calories from palm oil) consumption, LDLr-/- LCAT-/- double knockout mice, compared with LDLr-/- mice, had similar plasma concentrations of free (FC), esterified (EC), and apoB lipoprotein cholesterol, increased plasma concentrations of phospholipid and triglyceride, decreased HDL cholesterol, and 2-fold more aortic FC (142 +/- 28 versus 61 +/- 20 mg/g protein) and EC (102 +/- 27 versus 61+/- 27 mg/g). ApoE-/- LCAT-/- mice fed the atherogenic diet, compared with apoE-/- mice, had higher concentrations of plasma FC, EC, apoB lipoprotein cholesterol, and phospholipid, and significantly more aortic FC (149 +/- 62 versus 109 +/- 33 mg/g) and EC (101 +/- 23 versus 69 +/- 20 mg/g) than did the apoE-/- mice. LCAT deficiency resulted in a 12-fold increase in the ratio of saturated + monounsaturated to polyunsaturated cholesteryl esters in apoB lipoproteins in LDLr-/- mice and a 3-fold increase in the apoE-/- mice compared with their counterparts with active LCAT. We conclude that LCAT deficiency in LDLr-/- and apoE-/- mice fed an atherogenic diet resulted in increased aortic cholesterol deposition, likely due to a reduction in plasma HDL, an increased saturation of cholesteryl esters in apoB lipoproteins and, in the apoE-/- background, an increased plasma concentration of apoB lipoproteins.
PMID: 11719520 [PubMed - indexed for MEDLINE]
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Effects of high-fat, low-cholesterol diets on hepatic lipid peroxidation and antioxidants in apolipoprotein E-deficient mice.
Ferre N, Camps J, Paul A, Cabre M, Calleja L, Osada J, Joven J.
Centre de Recerca Biomedica, Hospital Universitari de Sant Joan, Cantalunya, Spain.
The present study describes the effects of several high-fat low-cholesterol antiatherogenic diets on the hepatic lipid peroxidation and hepatic antioxidant systems in apolipoprotein E-deficient mice. Eighty mice were distributed into five groups and fed with regular mouse chow or chow supplemented with coconut, palm, olive and sunflower seed oils. After ten weeks, they were sacrificed and the livers were removed so that lipid peroxidation and alpha-tocopherol concentrations, and superoxide dismutase, glutathione peroxidase and glutathione reductase activities could be measured. The size of the atherosclerotic lesions in the aortas was also measured. Results showed that the diets supplemented with olive oil, palm oil or sunflower seed oil significantly decreased the size of the lesion. However, there was an association between those mice that were on diets supplemented with palm or coconut oils and a significant increase in hepatic lipid peroxidation. This association was not found in animals fed with olive or sunflower seed oils, the diets with the highest content of vitamin E. The dietary content of vitamin E was significantly correlated (r = 0.98; p < 0.05) with the hepatic concentration of this compound. Our study suggests that the high content of vitamin E in olive oil or sunflower seed oil may protect from the undesirable hepatotoxic effects of high-fat diets in apo E-deficient mice and that this should be taken into account when these diets are used to prevent atherosclerosis.
PMID: 11330832 [PubMed - indexed for MEDLINE]
Vitamin E and factors affecting atherosclerosis in rabbits fed a cholesterol-rich diet.
Ismail NM, Abdul Ghafar N, Jaarin K, Khine JH, Top GM.
Department of Pharmacology, Faculty of Medicine, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
The present study aims to examine the effects of a palm-oil-derived vitamin E mixture containing tocotrienol (approximately 70%) and tocopherol (approximately 30%) on plasma lipids and on the formation of atherosclerotic plaques in rabbits given a 2% cholesterol diet. Eighteen New Zealand White rabbits (2.2-2.8 kg) were divided into three groups; group 1 (control) was fed a normal diet, group 2 (AT) was fed a 2% cholesterol diet and group 3 (PV) was fed a 2% cholesterol diet with oral palm vitamin E (60 mg/kg body weight) given daily for 10 weeks. There were no differences in the total cholesterol and triacylglycerol levels between the AT and PV groups. The PV group had a significantly higher concentrations of HDL-c and a lower TC/HDL-c ratio compared to the AT group (P < 0.003). The aortic tissue content of cholesterol and atherosclerotic lesions were comparable in both the AT and PV groups. However, the PV group had a lower content of plasma and aortic tissue malondialdehyde (P < 0.005). Our findings suggest that despite a highly atherogenic diet, palm vitamin E improved some important plasma lipid parameters, reduced lipid peroxidation but did not have an effect on the atherosclerotic plaque formation.
PMID: 11271860 [PubMed - indexed for MEDLINE]
Cholesterol vehicle in experimental atherosclerosis. 23. Effects of specific synthetic triglycerides.
Kritchevsky D, Tepper SA, Chen SC, Meijer GW, Krauss RM.
The Wistar Institute, Philadelphia, Pennsylvania 19104, USA. kritchevsky@wistar.upenn.edu
Earlier work has shown that increasing concentration of palmitic acid at the sn-2 position of a fat enhances the atherogenic properties of that fat. This effect has been observed with lard, tallow, cottonseed oil, and palm oil. In the experiment reported here, we have studied the atherogenic effects of four synthetic fats fed to rabbits as 58% (w/w) of the total fat (15%) (w/w) of a semipurified diet containing 0.05% cholesterol. The fats being tested were: 1,3-stearoyl-2-oleoylglycerol (SOS); 1,2-stearoyl-3-oleoylglycerol (SSO); 1,3-palmitoyl-2-oleoylglycerol (POP); and 1,2-palmitoyl-3-oleoylglycerol (PPO). After 20 wk on diet there were no differences among the groups in weight gain, liver weight, serum, or liver lipids. These data are consistent with our previous findings. There were significant differences in atherosclerosis. The most severe atherosclerosis was observed in group PPO and the least in groups SSO and POP. Severity of atherosclerosis was graded visually on a 0-4 scale. The average atherosclerosis [(aortic arch and thoracic aorta) divided by 2] was: SOS--1.35; SSO--0.97; POP--0.83; and PPO--1.80. Fecal fat excretion (an indicator of fat absorption) was higher in the two groups fed the stearic acid-rich fats and lower in groups fed the palmitic acid-rich fats. There were no differences in low density lipoprotein particle size. The results confirm previous findings concerning the increased atherogenicity of fats bearing palmitic acid at the sn-2 position. The mechanism underlying these observations is moot but may, in part, reflect greater absorption of the atherogenic fat.
PMID: 10901423 [PubMed - indexed for MEDLINE]
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Postprandial lipoprotein, glucose and insulin responses after two consecutive meals containing rapeseed oil, sunflower oil or palm oil with or without glucose at the first meal.
Pedersen A, Marckmann P, Sandstrom B.
Research Department of Human Nutrition, Royal Veterinary and Agricultural University, Frederiksberg, Denmark. anp@kvl.dk
There is increasing evidence that the degree of postprandial lipaemia may be of importance in the development of atherosclerosis and IHD. Postprandial lipid, lipoprotein, glucose, insulin and non-esterified fatty acid (NEFA) concentrations were investigated in eleven healthy young males after randomized ingestion of meals containing rapeseed oil, sunflower oil or palm oil with or without a glucose drink. On six occasions each subject consumed consecutive meals (separated by 1.75 h) containing 70 g (15 g and 55 g respectively) of each oil. On one occasion with each oil 50 g glucose was taken with the first meal. One fasting and fifteen postprandial blood samples were taken over 9 h. There were no statistically significant differences in lipoprotein and apolipoprotein responses after rapeseed, sunflower and palm oils, whereas insulin responses were lower after sunflower oil than after rapeseed oil (ANOVA, P = 0.04). The NEFA and triacylglycerol concentrations at 1.5 h were reduced when 50 g glucose was taken with the first meal (ANOVA, P < 0.0001 and P < 0.05 respectively), regardless of meal fatty acid composition. In conclusion, the consumption of glucose with a mixed meal containing either rapeseed, sunflower or palm oil influenced the immediate triacylglycerol and NEFA responses compared with the same meal without glucose, whereas no significant effect on postprandial lipaemia after a subsequent meal was observed. The fatty acid composition of the meal did not significantly affect the lipid and lipoprotein responses, whereas an effect on insulin responses was observed.
Publication Types:
PMID: 10743481 [PubMed - indexed for MEDLINE]
Low-cholesterol and high-fat diets reduce atherosclerotic lesion development in ApoE-knockout mice.
Calleja L, Paris MA, Paul A, Vilella E, Joven J, Jimenez A, Beltran G, Uceda M, Maeda N, Osada J.
Departamento de Bioquimica y Biologia Molecular y Celular, Facultad de Veterinaria, Universidad de Zaragoza, Spain.
We have investigated the effect of most common oils used in human nutrition on the development of atherosclerosis in apoE-knockout mice. Seven groups of animals, separated according to sex, were fed for 10 weeks either chow diet or the chow diet 10% (wt/wt) enriched with different oils (palm, coconut, 2 types of olive oil, and 2 types of sunflower oil) without addition of cholesterol. At the end of this period, plasma lipid parameters were measured and vascular lesions scored. None of the diets induced changes in plasma cholesterol concentrations, whereas plasma triglycerides were uniformly reduced in all diet groups. Some diets caused significant reductions in the size of atherosclerotic lesions in males and others in females; males responded most to sunflower oils and females to palm oil and one olive oil (II). The lesion reduction in males consuming sunflower oils was associated with the decrease of triglycerides in triglyceride-rich lipoproteins, whereas the decrease in females consuming olive oil II or palm oil was accompanied by an increase in plasma apoA-I. The increase in plasma apoA-I in the latter condition, is mainly due to overexpression of hepatic message elicited by a mechanism independent of apoE ligand. The data suggest that the different diets modulate lesion development in a gender specific manner and by different mechanisms and that the development of atherosclerosis, due to genetic deficiencies, may be modulated by nutritional maneuvers that may be implemented in human nutrition.
PMID: 10521366 [PubMed - indexed for MEDLINE]
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Influence of palm oil (Elaesis guineensis) on health.
Ebong PE, Owu DU, Isong EU.
Department of Biochemistry, University of Calabar, Nigeria.
In recent times there has been a growing research interest in palm oil, one of the major edible plant oils in the tropical countries, because of the link between dietary fats and coronary heart disease. Obtained from a tropical plant, Elaesis guineensis, it has a polyunsaturated fatty acid/saturated fatty acid ratio close to unity and a high amount of antioxidant vitamin A precursors and vitamin E. Palm oil is consumed in the fresh state and/or at various levels of oxidation. Feeding experiments in various animal species and humans have highlighted the beneficial role of fresh palm oil to health. These benefits include reduction in the risk of arterial thrombosis and atherosclerosis, inhibition of cholesterol biosynthesis and platelet aggregation, and reduction in blood pressure. However, a considerable amount of the commonly used palm oil is in the oxidized state which possesses potential dangers to the physiological and biochemical functions of the body. Oxidation is as a result of processing the oil for various culinary purposes. Studies have revealed that relative to fresh palm oil, oxidized palm oil induces an adverse plasma lipid profile, free fatty acids, phospholipids and cerebrosides. Additionally, oxidized palm oil induces reproductive toxicity and organotoxicity particularly of the kidneys, lungs, liver and heart. Available evidence suggests that at least part of the oxidized oil impact on health reflects generation of toxicants due to oxidation. The reduction of the dietary level of oxidized oil and/or the level of oxidation may reduce the health risk associated with consumption of oxidized fats.
Publication Types:
PMID: 10517280 [PubMed - indexed for MEDLINE]
The effect of intermittent heating on some chemical parameters of refined oils used in Egypt. A public health nutrition concern.
Tewfik IH, Ismail HM, Sumar S.
Department of Nutrition, University of Alexandria, Egypt.
As part of a public health campaign in Egypt, various chemical parameters of oil which are considered good indices in assessing the degree of thermal abuse, oxidation and overall quality (acid values, iodine values, peroxide values, etc.) were studied with respect to different frying oils. Ingestion of decomposition products formed as a results of thermal abuse and oxidation of frying oils are known to lead to a variety of symptoms and diseases (allergies, atherosclerosis, coronary heart disease). Results show that the oil most commonly used by street vendors in Egypt (blend of cotton seed and sunflower oil) is the least suitable for frying, while palm oil on the basis of the various chemical parameters studied, is the ideal choice. However, from the nutritional and public health stand point, the use of saturated oils is to be discouraged. Corn oil is therefore the next best choice from both the chemical and nutritional stand point, and is recommended for public use in a country in which deep-fried vegetable patties ('fallafel') forms the staple food item in the diet.
PMID: 10367003 [PubMed - indexed for MEDLINE]
Plasma clearance of chylomicrons from butterfat is not dependent on saturation: studies with butterfat fractions and other fats containing triacylglycerols with low or high melting points.
Phan CT, Mortimer BC, Martins IJ, Redgrave TG.
University of Western Australia, Department of Physiology, Nedlands, Perth, Australia. ctphan@cyllene.uwa.edu.au
BACKGROUND: Dietary fats influence plasma lipids, and changes in the clearance and metabolism of postprandial lipoproteins can affect atherosclerosis. Butterfat is considered hypercholesterolemic but contains a multitude of constituent fatty acids. OBJECTIVES: We determined triacylglycerol and cholesteryl ester clearances of lymph chylomicrons derived from butterfat, fractions of butterfat, and other dietary fats. METHODS: Radiolabeled lymph chylomicrons resulting from the intestinal absorption of different fats were reinjected into recipient rats to measure plasma clearance. Plasma clearance of [14C]triacylglycerol was used as an indicator of chylomicron lipolysis whereas clearance of [3H]cholesteryl ester was used as an indicator of chylomicron remnant removal. RESULTS: [3H]Cholesteryl ester clearance was slower from chylomicrons derived from a solid, high-saturated-butterfat fraction than from whole butterfat, but clearance of chylomicrons from other fractions did not correlate with the fractions' saturated fatty acid contents. Clearance of cholesteryl esters in chylomicrons derived from cocoa butter, palm oil, and butterfat was slower than clearance of cholesteryl esters in chylomicrons derived from safflower oil. Hepatic uptakes of cholesteryl esters were generally lower for chylomicrons from all butterfat fractions, cocoa butter, and palm oil. CONCLUSIONS: In contrast with minor effects on the lipolysis of chylomicron triacylglycerols, chylomicron remnant removal was strongly influenced by the type of dietary fat, with slower cholesteryl ester clearances for saturated fats with higher melting points. However, remnant removal and hepatic uptake of chylomicrons from whole butterfat and fractions of butterfat were not correlated with fat saturation. The mechanisms of this apparent paradox remain unknown but may be attributable to acyl arrangements in the lipid classes of chylomicrons that influence the association with apolipoproteins and receptors and hence remnant removal.
PMID: 10357733 [PubMed - indexed for MEDLINE]
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Marked inhibition of hepatic cytochrome P450 activity in cholesterol-induced atherosclerosis in rabbits.
Irizar A, Ioannides C.
Molecular Toxicology Group, School of Biological Sciences, University of Surrey, Guildford, UK.
The objective of the present study was to investigate the expression of major xenobiotic-metabolising cytochrome P450 proteins, and of other enzyme systems, in hepatic and extrahepatic tissues of rabbits rendered atherosclerotic by the dietary administration of 1% cholesterol diets for 8 weeks. Individual cytochrome P450 proteins were monitored using diagnostic substrates and immunologically in Western blot analysis. The activity of all hepatic isoforms studied was depressed in the atherosclerotic animals; when, however, apoprotein levels were determined immunologically, no major differences were evident between the control and the atherosclerotic rabbits. In vitro studies indicated that neither cholesterol nor palm oil inhibited cytochrome P450 activity. The effects of cholesterol treatment leading to atherosclerosis on kidney, heart and lung cytochrome P450 activities were isoform- and tissue-specific; no change was evident in the heart activities, but in the lung and kidney cytochrome P450 activities were clearly modulated by the treatment with cholesterol. Apoprotein levels did not always parallel the changes in activities. Western blot analysis of aortic cytochromes P450 revealed that administration of cholesterol-rich diets enhanced CYP2B and CYP3A apoprotein levels. Cholesterol feeding to rabbits gave rise to a marked decrease in hepatic glutathione S-transferase activity but did not influence glutathione reductase or total glutathione levels. The same treatment had no effect on catalase, glutathione peroxidase and superoxide dismutase. It is concluded that treatment of rabbits with cholesterol-rich diets leading to atherosclerosis gives rise to profound changes in the expression of cytochrome P450 proteins in the liver and other tissues; possible mechanisms are discussed.
PMID: 9674966 [PubMed - indexed for MEDLINE]
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Monounsaturated and polyunsaturated n-6 fatty acid-enriched diets modify LDL oxidation and decrease human coronary smooth muscle cell DNA synthesis.
Mata P, Varela O, Alonso R, Lahoz C, de Oya M, Badimon L.
Department of Medicine, Fundacion Jimenez Diaz, Universidad Autonoma Madrid, Spain.
Proliferation of smooth muscle cells (SMCs) plays an important role in atherosclerotic lesion progression. The purpose of this investigation was to examine the effect of diets differing in fatty acid composition on human coronary SMC entry in the cell proliferation cycle. Twenty-four healthy men and women were placed on four consecutive diets lasting 5 weeks each: (1) saturated fatty acid (SFA)-rich diet with palm oil; (2) monounsaturated fatty acid (MUFA)-rich diet with olive oil; (3) polyunsaturated fatty acid (PUFA) n-6-rich diet with sunflower oil; and (4) PUFA n-3-rich diet (3.8 g/d). All diets supplied 35% of calories as fat. Compared with the SFA diet, all unsaturated diets reduced LDL cholesterol. Resistance of LDL to oxidative modification was significantly increased during the MUFA period (P < .05). Human coronary SMCs were cultured and induced by sera derived from the different groups. 3H-Thymidine incorporation into doubling DNA was significantly (P < .01) reduced during the MUFA and PUFA n-6 periods but not during the PUFA n-3 diet with respect to the SFA diet. This effect was more pronounced in women than in men. In conclusion, the MUFA-enriched diet reduced SMC DNA synthesis and LDL levels and protected LDL from oxidation. Therefore, these combined effects suggest that an oleic acid-rich Mediterranean diet could be better than PUFA (n-6)- or PUFA (n-3)-rich diets in the prevention of atherosclerosis.
PMID: 9351376 [PubMed - indexed for MEDLINE]
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