Addition Of Dietary Cholesterol Research Articles

Alterations in Tissue Structure and Morphology in Apo E-KO Mice: The Impact of Dietary Lipids and Heart Transplantation

In this article, the impact of dietary lipids and heterotopic heart transplant procedures on the structure and morphology of several tissues in apolipoprotein E-knock out (apo E-KO) mice is reported. In particular, addition of dietary cholesterol, plant sterol or either changes in hemodynamic factors or immunological responses after heart transplant procedures are associated with histological and cytological changes in the kidneys, skin, heart and arteries in this animal model. In this report, alterations in the vessel wall structure and morphology including formation of atherosclerotic plaques, infiltration of macrophages, as well as evidence for rejection of the donor hearts and formation of non-specific vacuolation in the liver and kidney have been illustrated. In conclusion, various factors may cause changes in tissue structure and morphology which may lead to tissue dysfunction. Early detection of such changes and appropriate remedies including dietary and lifestyle modifications may help sustain tissue structure and function.

Modified Soybean Affects Cholesterol Metabolism in Rats Similarly to a Commercial Cultivar

The consumption of soy protein lowers blood cholesterol in humans and animals. Breeding may alter the physiological effects of soybeans, such as its cholesterol-lowering property. Our hypothesis is that breeding affects the hypocholesterolemic effect of soy by modulating the expression of key hepatic enzymes related to cholesterol and bile acid biosynthesis, as well as altering fecal neutral and acidic steroid excretion. Therefore the aim of this study was to evaluate the effect of a new Brazilian soybean cultivar (UFV-116), lacking lipoxygenases 2 and 3, compared with a commercial cultivar (OCEPAR-19), on 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) and cholesterol 7α-hydroxylase (CYP7A) mRNA expression and fecal steroid output in rats. Thirty-six male rats were fed UFV-116, OCEPAR-19, or casein as the protein source, with or without addition of dietary cholesterol (0.25%). Blood and liver cholesterol, HMGR and CYP7A mRNA abundance, and fecal excretion of steroids were measured. Blood and liver cholesterol levels were lowered by both soybean cultivars, with and without cholesterol, but UFV-116 was more effective when included in the cholesterol-free diet. Both soy diets promoted lower levels of HMGR mRNA, higher levels of CYP7A mRNA, and higher excretion of fecal secondary bile acids. There was higher fecal neutral steroid output when cholesterol was added to all diets. These data show that both soybean cultivars acted similarly in lowering serum and hepatic cholesterol; therefore, breeding did not affect the hypocholesterolemic effect of the new cultivar.

Effect of dietary cholesterol, trans and saturated fatty acids on serum lipoproteins in non-human primates.

Nine cynomolgus monkeys were rotated randomly through four dietary treatments with each treatment lasting 6 weeks. A wash-out period of 4 weeks was maintained between each dietary rotation. The animals were fed diets containing 32% energy fat derived from palm olein (POL), lauric-myristic-rich oil blend (LM), American Heart Association (AHA) rich oil blend and hydrogenated soybean oil blend (trans). Diets were fed with (phase 1) or without (phase 2) the addition of dietary cholesterol (0.1%). In phase 1, when animals were fed without dietary cholesterol, plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) was significantly raised and high-density lipoprotein cholesterol (HDL-C) was significantly depressed by the trans diets relative to all other dietary treatments. The resulting LDL-C/HDL-C ratio was also significantly increased. The LM diet increased TC significantly relative to the AHA diet while LDL-C was significantly increased compared to both POL and AHA. Apolipoprotein (apo) B was not affected significantly by these dietary treatments. Apo A1 was significantly increased by POL relative to all other dietary treatments. The trans diet reduced apo A1 and the resulting apo B/A1 ratio was increased significantly by trans relative to all other dietary treatments. Addition of 0.1% dietary cholesterol to these diets almost doubled the plasma TC and LDL-C in all dietary treatments. However, HDL-C was only marginally higher with the addition of dietary cholesterol. The LM + C (cholesterol added) diet resulted in the highest TC and LDL-C that was significant compared to all other dietary treatments. Trans + C increased TC compared to POL + C and AHA + C diets while increases in the LDL-C did not attain significance. The addition of dietary cholesterol did not affect HDL-C between treatments whereas plasma triglycerides were significantly increased by the trans + C diet relative to all other treatments. Both the trans + C and LM + C diets increased apo B and decreased apo A1 relative to the POL + C and AHA + C diets. The resulting apo B/A1 ratio was similarly altered. These results affirm that the lauric + myristic acid combination, along with trans fatty acids, increased lipoprotein-associated coronary heart disease risk factors compared to either POL or AHA.

Regulation of Plasma and Hepatic Lipids by Dietary Fatty Acids: Effects of Oleic, Elaidic and Palmitic Acids.

This study compares the effects of dietary oleic acid (OA), palmitic acid (PA), and trans fatty acids (TFA) on lipid metabolism in rabbits. Animals were fed semipurified diets in which a fifth of the fat intake (6% total energy) was either OA, PA, or TFA in the presence and absence of dietary cholesterol (0.2% w/w). After 10-12 weeks of feeding the cholesterol-free diets, there were no significant differences in plasma total cholesterol or triacylglycerol concentrations between groups. However, there was an increase in the cholesterol concentration of the lower density lipoproteins in rabbits fed the TFA diet compared with their OA- and PA-fed counterparts. The addition of dietary cholesterol had no effect on plasma lipids, however hepatic cholesterol concentrations were lower in animals fed the PA diet compared with those fed the OA diet (p<0.05), mainly due to a reduction in cholesteryl ester concentration (p<0.05). Despite these changes, hepatic low density lipoprotein (LDL)- receptor activity was not affected by diet. Palmitic and linoleic acids comprised similar proportions in the OA and TFA diets, however the proportion of hepatic phospholipid fatty acids as palmitic acid was lower (p<0.0001) while linoleic acid was higher (p<0.01) in animals fed TFA compared with those fed OA. These findings indicate that in rabbits fed dietary cholesterol (0.2%) TFA do not negatively impact on plasma lipids compared with either OA or PA. Also, increased esterification of TFA and linoleic acid to phospholipids at the expense of palmitic acid in animals fed TFA suggests that feeding TFA may result in cellular membranes with altered physical characteristics.

735 LIPOPROTEIN-CHOLESTEROL LEVELS IN YOUNG RATS FED DIETS EITHER SUPPLEMENTED OR DEFICIENT IN SELENIUM AND/OR VITAMIN

Dietary deficiences of antioxidant nutrients (vitamin E and selenium) were found to have major effects on rat plasma lipoprotein-cholesterol levels. Keanling Fischer-344 rats were fed a cholesterol free basal diet deficient in both vitamin E and selenium (B diet) or supplemented with either vitamin E (B+E diet) or selenium (B+Se diet) or both these micronutrients (B+E+Se diet), After 13 weeks, the rats fed diets deficient in selenium (B+E or B diets) developed elevated LDL-cholesterol (13±1 mg/dl plasma) compared with values for age-matched rats (7±1 mg/dl plasma) fed the selenium supplemented diets (B+Se or B+E+Se), VLDL-cholesterol levels (3.3+0.4 mg/dl) in rats fed the B diet deficient in both vitaiin E and selenium were significantly higher than values (0.6+0.2 mg/dl) for any of the other dietary groups. HDL-cholesterol levels were not significantly different in the various dietary groups. In a second experiment, diets identical to those in the first eiperiment Here used but were supplemented with 1% cholesterol. The addition of dietary cholesterol caused a marked increase in serum lipoprotein-cholesterol levels in all dietary groups. LDL-cholesterol was again selectively increased (37±6) in rats fed the selenium deficient diets (B+cho+E or B+cho) compared to values for age matched rats (22±7) fed the selenium supplemented diets (B+cho+Se or B+cho+E+Se). As in the first experiment, VLDL-cholesterol was increase only in rat fed the diet deficient in both vitamin E and selenium (B+cho diet). Dietary selenium deficiency in young rats, independent of vitamin E status, appears to increase LDL-cholesterol levels. In humans and many animal, models, LDL-cholesterol levels are a positive risk factor for atherosclerosis. (Supported by Grant RR-OB037-13 from DRR and NHLBI and by an Investigatorship from the Tennessee Affiliate of the AHA).

Relation between dietary cholesterol and bile acid excretion in the rat.

The influence of dietary cholesterol on fecal excretion of bile acids has been studied in rats fed isocaloric quantities of purified diets that varied only in cholesterol content. Addition of dietary cholesterol clearly resulted in an increase in excretion of total bile acids, as well as in conversion of cholesterol-4-C14 to bile acid-C14. An acceleration in bile acid excretion as a result of cholesterol feeding was demonstrated to be independent of dietary cholic acid and to occur despite suppression of the bowel flora. These results suggest that not only does absorbed dietary cholesterol play a role in determining the rate of bile acid formation but that the adaptation of bile acid synthesis to cholesterol feeding may in part be a determining factor in the varying response of different species to cholesterol feeding.

Influence of dietary cholesterol on excretion of cholesterol-4-C14 by the rat.

The influence of dietry cholesterol on the excretion of cholesterol-4-C14 has been studied in rats pair fed isocaloric quantities of purified diets supplemented with varying amounts of cholesterol and either oleic or linoleic acid. Of the C14 excreted over an 8-day period, slightly more than half was present in the neutral sterol fraction of feces from rats fed sterol-free diets. The addition of dietary cholesterol, however, under circumstances where significant cholesterol absorption was promoted by the addition of fatty acids to the diets, resulted in a reversal of this ratio so that the bile acid fraction accounted for the major portion of excreted cholesterol-C14. Cholesterol balance data revealed that the degradation rate of cholesterol in these animals rose to about 17–20 mg/day. These data are interpreted as demonstrating that the amount of absorbed dietary cholesterol plays a crucial role in determining both the relative and absolute importance of the two major routes of cholesterol excretion.