| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Effect of dietary deoxycholic acid and cholesterol on fecal steroid concentration and its impact on the colonic crypt cell proliferation in azoxymethane-treated rats Hori, T., K. Matsumoto, et al. (1998), Cancer Lett 124(1): 79-84. Abstract: To elucidate the role of fecal steroids in the malignant tumor formation of colonic epithelial cells, we examined the effects of dietary deoxycholic acid (DCA) and cholesterol (CHL) on fecal steroid concentrations and their impact on colonic crypt cell proliferation. Twenty 5-week-old male Fischer 344 rats were provided with either a control semisynthetic diet or the same diet supplemented with 0.15% DCA and 1% CHL (steroid diet) over a 5-week period. The effects of these two diets were compared among rats that were either injected with azoxymethane (AOM), a known gastrointestinal carcinogen, or saline. In a 2 x 2 factorial design, rats fed each of these diets were given two weekly subcutaneous injections of either AOM (15 mg/kg b.w.) or saline at 6 and 7 weeks of age. At 9 weeks of age, fecal samples were obtained for analysis of bile acids, CHL and its bacterial metabolites of intestinal microflora. At 10 weeks of age, animals were sacrificed and colonic proliferation was assessed as vincristine-accumulated mitotic figures per crypt. Rats fed the steroid diet had significantly elevated fecal bile acid (5x, P < 0.001) and neutral steroid (10x, P < 0.01) levels when compared to those fed the control diet. AOM treatment did not appear to influence these levels. However, rats injected with AOM had a significant increase (P < 0.001) in their rate of colonic cell proliferation as compared to saline-injected control animals on both diets. Furthermore, rats fed the steroid diet had a significantly higher (P < 0.001) cell proliferation rate than animals fed the control diet. The effects of AOM treatment and the steroid diet on cell proliferation were additive. Our results demonstrate that high concentrations of neutral and acid steroids in the colonic lumen can enhance carcinogen-induced elevated cell proliferation and thus may play a key role in the etiology of colon cancer. |
| Effect of dietary ethanol on gallbladder absorption and cholesterol gallstone formation in the prairie dog Kurtin, W. E., W. H. Schwesinger, et al. (1991), Am J Surg 161(4): 470-4. Abstract: Dietary ethanol has been reported to protect against cholesterol gallstone formation. Because enhanced gallbladder absorption of water is important in cholesterol cholelithiasis, we examined the hypothesis that ethanol acts by inhibiting the absorptive function of the gallbladder. Eighteen adult male prairie dogs were fed a lithogenic liquid diet containing 0.4% cholesterol. Half of the animals received 30% of total calories as ethanol, whereas their pair-fed controls received equicaloric amounts of maltose-dextrin. After 3 months, the gallbladders were inspected for gallstones and crystals, and gallbladder and hepatic bile were analyzed. Cholesterol stones and crystals were present in all nine controls. None of the alcohol-fed animals had stones, but four had cholesterol crystals. Gallbladder cholesterol, phospholipids, and total calcium were significantly decreased in alcohol-fed animals. In both gallbladder and hepatic bile, the cholesterol saturation index was significantly lower in alcohol-fed animals, as was the ratio of trihydroxy to dihydroxy bile salts. The ethanol-supplemented diet produced a significant decrease in the absorption of water by the gallbladder as indicated by changes in the gallbladder bile to hepatic bile ratios of the total bile salt concentration (7.29 +/- 1.25 versus 3.84 +/- 0.56; p less than 0.05) and the total calcium (3.37 +/- 0.24 versus 2.43 +/- 0.29; p less than 0.05). These findings indicate that the protective effect of ethanol may be related to its ability both to inhibit gallbladder absorption of water and to alter the composition of biliary lipids. |
| Effect of dietary fat and cholesterol level on growing pigs selected for three generations for high or low serum cholesterol at age 56 days Pond, W. G., W. Insull, et al. (1992), J Anim Sci 70(8): 2462-70. Abstract: Thirty-six female pigs selected for three generations for high (HS, n = 18) and low (LS, n = 18) serum cholesterol at 56 d of age were used to test the hypothesis that the two populations would respond differently to a high-fat, high-cholesterol diet (HD) and a low-fat, low-cholesterol diet (LD). The animals were four-way crosses (Chester White x Landrace x Large White x Yorkshire). All pigs were fed a standard corn-soybean meal starter diet from weaning (at 4 wk) to 8 wk of age and a grower diet from 8 to 12 wk of age. Initial serum total cholesterol concentration at 12 wk of age was higher (P less than.05) in HS than in LS pigs (94.6 vs 76.9 mg/dL, respectively). The effect of genetic background persisted throughout the 13-wk experiment (25 wk of age); there was no interaction between diet and genetic background in serum total cholesterol (final concentrations were 114.3 mg/dL in HS-HD; 107.0 mg/dL in HS-LD; 105.9 mg/dL in LS-HD; and 89.7 mg/dL LS-LD). Trends over time revealed significant effects of diet (P less than.01) and genetic background (P less than.01) on serum total cholesterol. There was no effect of genetic background on high-density lipoprotein-cholesterol concentration; high-density lipoprotein-cholesterol as a percentage of serum total cholesterol was similar for all groups: 43% for HS-HD, 48% for HS-LD, 42% for LS-HD, and 45% for LS-LD.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Effect of dietary fat and cholesterol level on tissue cholesterol concentrations of growing pigs selected for high or low serum cholesterol Harris, K. B., H. R. Cross, et al. (1993), J Anim Sci 71(4): 807-10. Abstract: Thirty-six female pigs selected for three generations for high or low serum cholesterol were chosen to evaluate the effects of a high-fat, high-cholesterol diet and a low-fat, low-cholesterol diet provided on an ad libitum basis for 92 d beginning at 12 wk of age on the cholesterol content and percentage of fat in muscle and organ tissues. The pigs were four-way crosses (Chester White x Landrace x Large White x Yorkshire). Samples of cerebrum, heart, ileum, kidney, liver, longissimus muscle, semitendinosus muscle, and subcutaneous fat were collected from each animal for determination of cholesterol concentration. The liver was the only tissue that had a significant difference in cholesterol content and in fat percentage between the genetic groups (high serum cholesterol and low serum cholesterol) and between the two diets (high-fat, high-cholesterol diet and low-fat, low-cholesterol diet). There were no interactions between diet and genetic background on cholesterol accretion or on the percentage of fat in the tissues. |
| Effect of dietary fat and cholesterol on dimethylbenza-anthracene-induced mammary tumorigenesis in Sprague-Dawley rats Nakayama, M., H. R. Ju, et al. (1993), Anticancer Res 13(3): 691-8. Abstract: The effect of dietary fats and cholesterol on dimethylbenza-anthracene-induced mammary tumorigenesis was studied in female Sprague-Dawley rats. When the dietary fat source (at the 5% level) was palm oil (saturated fat) or corn oil (unsaturated fat), dietary cholesterol at the 0.2% level increased the tumor number of rats fed corn oil, but not those fed palm oil. Perilla oil (rich in alpha-linolenic acid) reduced tumor development as compared with safflower oil (rich in linoleic acid), but again dietary cholesterol at the 0.5% level diminished the favorable effect of n-3 polyunsaturated fatty acid (PUFA). The adverse effect of cholesterol was also observed in the n-6 PUFA fat. The promotive effect of dietary cholesterol was not necessarily associated with the change in the production of prostaglandin E2 by the tumor tissue or in the immunopotentiation. These results at least stress that the contrasting effects of dietary fats should be carefully evaluated whether cholesterol is present simultaneously or not. |
| Effect of dietary fat composition on biliary cholesterol saturation index in dogs Ballesta, M. C., E. Martinez-Victoria, et al. (1993), Arch Int Physiol Biochim Biophys 101(1): 3-7. Abstract: In dogs, the effect of dietary fat on bile cholesterol saturation index and the evolution of molar percentages of biliary lipids have been studied in both fasting and postprandial periods after a long-term adaptation period to diets which only differ in their lipidic source (olive oil and sunflower oil). It has been observed that for similar bile cholesterol saturation indexes in both groups, dietary fat altered differently biliary lipid composition through a double mechanism which involved bile acids and phospholipids. Dietary fat is postulated to affect differently the lipidic composition of bile as well as the biliary tree motility both during interdigestive and postprandial periods. |
| Effect of dietary fat on rat liver microsomal and mitochondrial/lysosomal dolichol, phospholipid and cholesterol Jakobsson-Borin, A., O. Tollbom, et al. (1991), Lipids 26(11): 915-21. Abstract: The influence of different fat diets on liver phospholipid, cholesterol and dolichol was studied. Rats were separated into four groups and fed standard laboratory chow (control), a diet containing linolenic acid, a coconut oil diet, or a corn oil-containing diet. After five weeks, microsomes and mitochondrial/lysosomal fractions were prepared from the liver, and lipid compositions were analyzed. No changes in phospholipid content were observed. In control animals, the fatty acid compositions of phosphatidylcholine and phosphatidylethanolamine in the two subfractions were similar. However, these two phospholipids showed different fatty acid patterns, which were altered independently upon dietary treatment. The dietary treatments resulted, in most cases, in decreased cholesterol and dolichol contents and, especially in microsomes, in a decreased level of esterification of both lipids. The fatty acid compositions of cholesteryl esters in the two subfractions showed significant differences and cholesterol was esterified to a large extent with linolenic acid when this fatty acid was supplied in the diet. The same dietary treatment exerted different effects on the cholesterol localized in the two different intracellular compartments. This difference was most pronounced in rats fed the corn oil-containing diet; microsomal cholesteryl esters exhibited increased saturation, whereas cholesteryl esters exhibited increased saturation, whereas cholesteryl esters in the mitochondrial/lysosomal fraction displayed decreased saturation. Dolichyl esters in the two cellular compartments had different fatty acyl compositions, with a considerably higher degree of saturation in microsomes. The various diets influenced the nature of the fatty acid moieties present in the isolated fractions and the effects on the two subfractions were opposite.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Effect of dietary fat saturation and cholesterol on LDL composition and metabolism. In vivo studies of receptor and nonreceptor-mediated catabolism of LDL in cebus monkeys Nicolosi, R. J., A. F. Stucchi, et al. (1990), Arteriosclerosis 10(1): 119-28. Abstract: The mechanism(s) by which polyunsaturated fats reduce low density lipoprotein (LDL) cholesterol and apolipoprotein (apo) B were investigated in 20 cebus monkeys (Cebus albifrons) fed diets containing corn oil or coconut oil as fat (31% of calories) with or without dietary cholesterol (0.1% by weight) for 3 to 10 years. Coconut-oil feeding compared to corn-oil feeding resulted in significant increases in levels of plasma total cholesterol (176%), very low density lipoprotein (VLDL)-LDL cholesterol (236%), high density lipoprotein (HDL) cholesterol (148%), apo B (78%), and apo A-I (112%). The addition of dietary cholesterol to corn oil compared to corn oil alone resulted in smaller, but significant, increases in levels of total cholesterol (44%), HDL cholesterol (40%), and apo A-I (33%). Although the increases in VLDL-LDL cholesterol were of similar magnitude (52%), they barely failed to reach statistical significance (p less than 0.08), while the changes in apo B levels were negligible. The addition of dietary cholesterol to coconut oil, compared to coconut oil alone, resulted in no significant changes in lipoprotein cholesterol or apoproteins, although levels of VLDL-LDL cholesterol and apo B values increased 22% and 16%, respectively. Although hepatic free cholesterol content was not altered by diet, coconut-oil compared to corn-oil feeding resulted in significant increases in hepatic cholesteryl esters (236%) and triglycerides (325%), the latter increasing still further when dietary cholesterol was added to coconut oil (563%). To further assess the effects of these dietary changes on LDL metabolism, radioiodinated normal and glucosylated LDL kinetics were performed. The production rate of LDL apo B was not altered by diet. With corn-oil feeding, 63% of LDL catabolism was via the receptor-mediated pathway. Coconut-oil compared to corn-oil feeding resulted in a 50% decrease in receptor-mediated LDL apo B fractional catabolic rate (FCR) and a 27% reduction in nonreceptor-mediated LDL apo B FCR. The addition of dietary cholesterol to corn oil, compared to corn oil alone, resulted in no significant effect on LDL apo B catabolism. The addition of dietary cholesterol to coconut oil, compared to coconut oil alone, was associated with no significant change in nonreceptor catabolism of LDL apo B but with a 58% decrease in receptor-mediated catabolism of LDL (p less than 0.059). The diet-induced alterations of LDL catabolism were significantly correlated with hepatic lipids, which were enriched in saturated fatty acids.(ABSTRACT TRUNCATED AT 400 WORDS) |
| Effect of dietary fat selection on plasma cholesterol synthesis in older, moderately hypercholesterolemic humans Jones, P. J., A. H. Lichtenstein, et al. (1994), Arterioscler Thromb 14(4): 542-8. Abstract: To study factors controlling plasma cholesterol levels, the effect of dietary fat type on cholesterol synthesis was examined in 15 hypercholesterolemic subjects (low-density lipoprotein LDL cholesterol > 130 mg.dL-1) consuming over a period of 32 days (1) a baseline diet (36% kcal as fat: 15% saturated, 15% monounsaturated, and 6% polyunsaturated fat; 180 mg cholesterol.1000 kcal-1) and diets meeting National Cholesterol Education Program step 2 criteria (30% kcal as fat, < or = 7% saturated fat, 80 to 85 mg cholesterol/Mcal), where two thirds of the fat was either (2) olive, (3) corn, or (4) canola oil. Plasma total, LDL, and high-density lipoprotein (HDL) cholesterol and triglyceride levels were determined at the end of each period. Cholesterol fractional synthesis rate (FSR) was also measured as the deuterium (D) incorporation into plasma total cholesterol relative to body D2O level (1.2 g D2O.kg-1 estimated body water) over 24 hours. Absolute synthesis rates (ASRs) were determined as the product of FSR and rapid turnover cholesterol pool size. Plasma total and LDL cholesterol levels declined significantly (P <.005) on all plant-oil diets compared with the baseline diet; however, triglyceride levels were not different. FSRs were higher (P <.05) for the corn oil (0.0665 +/- 0.0097 pool.d-1) compared with baseline (0.0412 +/- 0.0060 pool.d-1) and olive oil (0.0409 +/- 0.0052 pool.d-1) but not canola oil (0.0492 +/- 0.0072 pool.d-1) diets.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Effect of dietary fats on cholesterol metabolism and eicosanoid production in hamsters fed undigested fraction of soybean protein Gatchalian-Yee, M., M. Imamura, et al. (1994), J Nutr Sci Vitaminol (Tokyo) 40(5): 499-504. Abstract: The undigested fraction of soybean protein (UDF) exerts a markedly greater hypocholesterolemic effect than soybean protein itself in rats. The present study was undertaken to confirm the effect in hamsters, a more appropriate animal model for human cholesterol metabolism. Hamsters were given diets containing UDF at a nitrogen level equivalent to the 20% casein diet. Dietary fats, at the 10% level, were perilla oil and safflower oil. There was apparently no increase in the serum and liver cholesterol levels in both groups of animals cholesterol-enriched diets that had been fed for 38 days. Fecal excretion of neutral and acidic steroid tended to be higher in the perilla oil group than in the safflower oil group. The perilla oil group significantly increased 20:5n-3 in liver phosphatidylcholine and phosphatidylethanolamine accompanying a decrease in 20: 4n-6. Such changes were not so evident in liver phosphatidylinositol. The production of leukotriene B4 and the concentration of prostaglandin E2 in the spleen were higher in the safflower oil group than in the perilla oil group. Thus, the hypocholesterolemic effect of the undigested fraction of soybean protein was apparently reproduced even in hamsters. Dietary fat-induced changes in lipid parameters in hamsters resembled those observed in rats. |
| Effect of dietary fats rich in lauric, myristic, palmitic, oleic or linoleic acid on plasma, hepatic and biliary lipids in cholesterol-fed hamsters Trautwein, E. A., A. Kunath-Rau, et al. (1997), Br J Nutr 77(4): 605-20. Abstract: Effects of different dietary fats on plasma, hepatic and biliary lipids were determined in male golden Syrian hamsters (Mesocricetus auratus) fed on purified diets for 7 weeks. Diets were made by blending different fats containing characteristic fatty acids: butter (14:0 + 16:0), palm stearin (16:0), coconut oil (12:0 + 14:0), rapeseed oil (18:1), olive oil (18:1) and sunflowerseed oil (18:2). In all diets except the sunflowerseed oil diet dietary 18:2 was held constant at 2% energy. Total fat supplied 12% of energy and cholesterol was added at 4 g/kg diet. Plasma cholesterol and triacyglycerol concentrations were increased by dietary cholesterol. After 7 weeks, plasma cholesterol concentrations were highest with the palm stearin, coconut oil and olive oil diets (8.9, 8.9 and 9.2 mmol/l) and lowest with the rapeseed oil and sunflowerseed oil diets (6.7 and 5.5 mmol/l) while the butter diet was intermediate (8.5 mmol/l). Hepatic cholesterol concentration was highest in hamsters fed on the olive oil diet and lowest with the palm stearin diet (228 v. 144 mumol/g liver). Biliary lipids, lithogenic index and bile acid profile of the gall-bladder bile did not differ significantly among the six diets. Although the gallstone incidence was generally low in this study, three out of 10 hamsters fed on the palm stearin diet developed cholesterol gallstones. In contrast, no cholesterol gallstones were found with the other diets. Rapeseed and sunflowerseed oils caused the lowest plasma cholesterol and triacyglycerol concentrations whereas olive oil failed to demonstrate a cholesterol-lowering effect compared with diets rich in saturated fatty acids. Since 18:2 was kept constant at 2% of energy in all diets, the different responses to rapeseed and olive oils could possibly be attributed to their different contents of 16:0 (5.6% v. 12.8% respectively). Other possible explanations are discussed. |
| Effect of dietary fish oil on plasma lipoprotein cholesterol in rats fed a diet enriched in cholesterol and sucrose Chiang, M. T. and M. L. Tsai (1997), Int J Vitam Nutr Res 67(3): 196-200. Abstract: The aim of this study was to examine the effect of dietary fish oil on plasma lipoprotein cholesterol levels in rats fed different carbohydrate sources. Male Wistar rats fed a soy bean oil diet or a fish oil diet containing 0.5% cholesterol were studied for 7 weeks. Corn starch or sucrose were used as carbohydrate sources in the experimental diet. Fish oil supplementation significantly (p < 0.05) decreased plasma VLDL (very low density lipoprotein) cholesterol in rats fed a diet containing corn starch. However, there was no significant difference in plasma total cholesterol and LDL (low density lipoprotein) cholesterol in rats fed a corn starch diet with fish oil treatment. In the experiment with sucrose, significantly (p < 0.05) decreased plasma total cholesterol, LDL cholesterol and VLDL cholesterol were observed in rats fed a fish oil diet. Although higher plasma total and VLDL cholesterol levels were found in rats fed the sucrose diet when compared with those fed the corn starch diet, no significant difference between the corn starch group and the sucrose group was observed in rats after fish oil treatment. Results from the present study suggest that the carbohydrate source might play an important role in the regulation of plasma lipoprotein metabolism in rats fed fish oil. |
| Effect of dietary fish oil on serum lipids and lipoproteins of rats fed diets differing in cholesterol and fat Stangl, G. I., K. Eder, et al. (1994), Arch Tierernahr 46(2): 155-64. Abstract: The investigation was attempted to clarify the effects of fish oil on the concentration of lipids in serum and lipoproteins in rats fed diets differing in cholesterol and fat. Male Sprague-Dawley rats were maintained on low-fat/high-fat diets without and with 1.5% cholesterol (base diets) for 28 days. Half of each group was then switched to a fish oil diet for 20 days with 5.6% fish oil for exchange of coconut oil and beef tallow. Total cholesterol in rat serum was increased following feeding high amounts of dietary cholesterol. This increase was due to raised VLDL and LDL cholesterol. Rats fed the high-cholesterol/high-fat diet had lower HDL cholesterol concentration than groups fed the other base diets. Dietary fish oil lowered serum and lipoprotein cholesterol, even in the presence of dietary cholesterol. In rats fed the high-fat/cholesterol-free diet triglyceride levels in total serum and VLDL were higher than in rats fed the other base diets. The hypertriglyceridemia in rats was diminished fed dietary cholesterol. Serum triglyceride concentration was markedly lowered by fish oil, whereas, this effect reached significance only using cholesterol-free diets. This was mainly associated with a reduction in VLDL triglycerides. Fish oil lowered HDL triglycerides only in rats fed the low-fat diet without cholesterol. Lipid components in the base diets did not influence serum and LDL phospholipids. Rats fed the high-fat/cholesterol-free diet had a higher VLDL phospholipid level than the other base groups. Irrespective of the base diet, phospholipid levels in serum and lipoproteins were markedly reduced by dietary fish oil. In conclusion, this study suggests that other dietary lipids should be considered when examining the hypolipemic effect of fish oil. |
| Effect of dietary fish on antioxidant parameters of normal and cholesterol stressed rats Nandini, M., M. A. Rahiman, et al. (1999), Indian J Exp Biol 37(12): 1187-91. Abstract: Feeding fish (Sardinella longiceps) to normal rats increased lipid peroxidation and total and Se-dependent glutathione peroxidase (GSH-px) activity in erythrocytes and manganese dependent superoxide dismutase (Mn-SOD) activity in liver. Feeding fish to cholesterol stressed rats showed a significant increase in the activity of GSH-px and cholesterol feeding alone, resulted in a significant increase in the lipid peroxidation and liver Mn-SOD activity. The results suggest that the high polyunsaturated fatty acid content of S. longiceps, the fish abundantly available in the west coast of India, does not have any deleterious effect by way of free radical generation. The observed lipid peroxidation is not critical as is evident from the results of glutathione level and other scavenging enzymes. |
| Effect of dietary hydrogenated corn oil (trans-octadecenoate rich oil) on plasma and hepatic cholesterol metabolism in the hamster Hayashi, K., Y. Hirata, et al. (1993), Atherosclerosis 99(1): 97-106. Abstract: The effect of dietary hydrogenated corn oil (trans-octadecenoate-rich oil) on plasma cholesterol and triglyceride concentrations was compared with dietary palmitic acid in hamsters given a cholesterol-rich diet. The addition of dietary palmitic acid and hydrogenated corn oil accelerated the increase in plasma VLDL- and LDL-cholesterol levels and plasma triglyceride level induced by dietary cholesterol loading. Dietary cholesterol, palmitic acid and hydrogenated corn oil showed no effect on plasma HDL-cholesterol concentration. A decrease in hepatic LDL receptor activity was seen in animals fed a diet supplemented with cholesterol in combination with palmitic acid or hydrogenated corn oil in comparison with animals fed a diet supplemented with cholesterol alone. Hydrogenated corn oil (trans-octadecenoate-rich oil) appears to potentiate the effect of dietary cholesterol in elevating the plasma VLDL- and LDL-cholesterol levels through the suppression of hepatic LDL receptor activity. trans-Octadecenoate in dietary hydrogenated corn oil may be as atherogenic as dietary palmitic acid due to a suppression of hepatic LDL receptors in the presence of dietary cholesterol loading. |
| Effect of dietary lipid-lowering drugs upon plasma lipids and egg yolk cholesterol levels of laying hens Mori, A. V., C. X. Mendonca, Jr., et al. (1999), J Agric Food Chem 47(11): 4731-5. Abstract: To evaluate the effect of lipid-lowering agents upon egg quality, reproductive performance, plasma lipids, and egg yolk cholesterol levels, 30-week-old Shaver laying hens were fed a basal diet (commercial ration) supplemented with 0.1% probucol (PROB), 0.025% gemfibrozil (GEMF), or lovastatin at 0.0005% (LOV1), 0.001% (LOV2), or 0.0015% (LOV3) for a 12-week experimental period. It was observed that the supplementation of the drugs did not impair albumen and shell quality. Hen performance was not adversely affected. The depression in triglyceride concentrations approached statistical significance only in LOV2 (38.5%), and total cholesterol was significantly depressed in LOV2 (36.0%), LOV3 (36.8%), PROB (29.6%), and GEMF (30.4%) treatments. Egg cholesterol content, expressed per gram of yolk, was significant lowered in LOV1 (7.5%) and LOV3 (12. 7%). |
| Effect of dietary magnesium deficiency with/without cholesterol supplementation on phospholipid content in liver, plasma and erythrocytes of rabbits Zhou, Q., M. M. Mahfouz, et al. (1994), Magnes Res 7(1): 23-30. Abstract: The effect of magnesium deficiency with/without supplementary cholesterol on phospholipid content in liver, plasma and erythrocytes was investigated in New Zealand White male rabbits. After the rabbits had been fed a low magnesium and/or high cholesterol diet for seven weeks, the phospholipid content in liver, plasma and erythrocytes was measured. Dietary magnesium deficiency produced a marked elevation of total phospholipid and certain individual phospholipids in the rabbit liver. The elevation was accentuated by cholesterol supplementation. In the plasma, a low magnesium intake enhanced plasma phosphatidylcholine, phosphatidic acid, phosphatidylinositol, and sphingomyelin, but an activated conversion from phosphatidylethanolamine to phosphatidylcholine made the increase in phospholipid insignificant. On the other hand, a low magnesium intake restricted the increase in magnitude of phospholipid caused by cholesterol supplementation. In the erythrocytes, total phospholipid, phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine were decreased by a low magnesium and/or a high cholesterol intake. We suggest that the increased contents of total phospholipid and/or certain individual phospholipids in the livers and plasma resulted from the enhanced synthesis of phospholipid in the liver by low magnesium intake. A decreased utilization of food by low magnesium diet limited the magnitude of plasma phospholipid increase produced by cholesterol supplementation. |
| Effect of dietary magnesium on development of atherosclerosis in cholesterol-fed rabbits Ouchi, Y., R. E. Tabata, et al. (1990), Arteriosclerosis 10(5): 732-7. Abstract: The effect of dietary magnesium (Mg) on the development of atherosclerosis in cholesterol-fed rabbits was investigated. Male New Zealand White rabbits (n = 31) were placed on five kinds of diets: regular, 1% cholesterol, and 1% cholesterol diets supplemented with either 300, 600, or 900 mg (as Mg) of Mg sulfate. The regular and 1% cholesterol diets contained 400 mg of Mg per 100 g. Each rabbit received 100 g daily of the appropriate diet. Additional Mg was well tolerated and did not affect blood pressure or body weight. The rabbits were sacrificed after 10 weeks, and the oil red O-positive atherosclerotic area that covered the aortic intima and the cholesterol content of the aorta was measured. Additional Mg decreased both the area of the aortic lesions and the cholesterol content of the aortas in a dose-dependent manner. The 1% cholesterol diet significantly increased plasma cholesterol and triglyceride concentrations and decreased high density lipoprotein (HDL) cholesterol concentration. Additional Mg had no further effect on cholesterol and HDL cholesterol concentrations, but it slightly decreased the rise in triglyceride concentration. These results indicate that dietary Mg prevents the development of atherosclerosis in cholesterol-fed rabbits by inhibiting lipid accumulation in the aortic wall. |
| Effect of dietary n-3 versus n-6 polyunsaturated fatty acids on hepatic excretion of cholesterol in the hamster Berr, F., A. Goetz, et al. (1993), J Lipid Res 34(8): 1275-84. Abstract: Dietary polyunsaturated fatty acids of the n-6 and the n-3 class show differing effects on serum lipids and hepatic lipoprotein metabolism, which could be induced by alterations in hepatocellular cholesterol balance. As both fatty acid classes exert parallel effects on lipoprotein uptake and synthesis of cholesterol in the liver, we studied whether they have differing effects on the excretory pathways for cholesterol. Male Syrian hamsters were fed for 3 weeks low-cholesterol diets supplemented (9% w/w) with either saturated (coconut fat), n-6 unsaturated (safflower oil) or n-3 unsaturated fatty acids (fish oil), which shifted the serum lipid levels. N-6 unsaturated fatty acids increased both the synthesis of cholic acid (+57%; P = 0.05) and, in fistula bile, the secretion of cholesterol (+37%; P < 0.05 vs. saturated fatty acids). By contrast, n-3 unsaturated fatty acids did not enhance synthesis of cholic acid or biliary secretion of cholesterol (-30%, NS). The fatty acid pattern of biliary phospholipids was modified according to the major unsaturated fatty acids in the diet. The alterations both in phospholipid fatty acid composition and in secretory ratio of cholesterol to phospholipids and bile acids persisted during controlled secretion of taurocholic acid at increasing rates. In conclusion, hepatic excretion of cholesterol is increased on dietary n-6 unsaturated fatty acids, and low on n-3 unsaturated fatty acids. These two dietary fatty acid classes change differently the fatty acid composition of biliary phospholipids and the secretory ratio of cholesterol to phospholipids and bile acids in bile. |
| Effect of dietary oils and alpha-tocopheryl acetate supplementation on lipid (TBARS) and cholesterol oxidation in cooked pork Rey, A. I., J. P. Kerry, et al. (2001), J Anim Sci 79(5): 1201-8. Abstract: The effect of n-3 fatty acid-enriched diets (in the form of 0.5% linseed oil with either 1.5% sunflower oil or 1.5% olive oil) and alpha-tocopheryl acetate supplementation (200 mg/kg feed) on lipid oxidation (thiobarbituric acid-reactive substances, TBARS) and cholesterol oxide products (COPS) in cooked pork was investigated. Longissimus muscle was studied. Meat from pigs fed 0.5% linseed oil-enriched diets had a higher proportion of n-3 fatty acid than meat from pigs in other dietary groups in neutral (P < 0.0001) and polar lipids (P < 0.0001), and a 20% reduction in the n-6:n-3 ratio was observed. Alpha-tocopheryl acetate supplementation increased (P < 0.05) monounsaturated fatty acids in polar lipids and increased (P = 0.0001) alpha-tocopherol levels in muscle. Alpha-tocopherol concentration in muscle was affected by dietary fat (P < 0.05). Groups receiving diets enriched with sunflower oil had significantly higher alpha-tocopherol levels (P < 0.05) in muscle than those groups receiving olive oil-enriched diets. Numbers of TBARS were significantly (P < 0.05) lower in the group fed supplemental olive oil than in those fed sunflower oil. Dietary linseed oil increased (P < 0.05) lipid oxidation principally at the initial period of storage in cooked pork. Overall, dietary alpha-tocopheryl acetate supplementation significantly increased (P < 0.001) lipid stability and decreased (P < 0.05) total COP production across the dietary groups. Alpha-tocopherol was a more effective antioxidant for decreasing TBARS values in cooked meat when adding sunflower oil to the diets instead of olive oil. |