ApoE distribution among lipoproteins of rhesus monkeys is modulated by dietary fat and cholesterol

The effect of dietary saturated fat and cholesterol on plasma cholesterol and apolipoprotein E (apoE) distribution among lipoproteins was studied in rhesus monkeys. Two groups of four monkeys had been fed diets containing 31% energy as either corn oil or coconut oil for 5 yr from birth. Each group was then fed short-term their respective diet with a 0.2% cholesterol supplement, the opposite fat without cholesterol, the opposite fat +0.2% cholesterol, followed by their original fat without cholesterol for 5 to 8 wk periods. Plasma was assayed for total cholesterol, total triglyclerides, and the distribution of apoE within lipoproteins (VLDL, IDL, LDL, HDL) separated by gradient-density electrophoresis. When coconut oil was fed, plasma cholesterol and triglyceride concentrations were 134% and 157%, respectively, of the levels when corn oil was fed. Cholesterol supplementation of corn oil also elevated the plasma cholesterol (141%), whereas cholesterol supplementation of coconut oil appeared to induce a synergistic increase (198%). Both groups of monkeys responded similarly to a given diet. The distribution of apoE in lipoproteins differed according to dietary treatment, with cholesterol feeding causing a major shift from HDL to IDL, whereas coconut oil caused a modest shift from HDL to VLDL. The relative amount of apoE in LDL was unchanged by diet. We conclude that dietary saturated fat or cholesterol can modulate the apoE distribution within lipoproteins in rhesus monkeys in conjunction with the previously noted expansion of the cholesteryl ester pool in VLDL and IDL.     

Dietary restriction amplifies the hypercholesterolemic effect of cholesterol feeding in the rat

Dietary restriction (half of the control ration) was performed in rats given either standard or hypercholesterolemic diets. The plasma cholesterol was measured throughout the 2 month experiment after which time the lipoproteins were analysed. Underfed rats with or without cholesterol supplementation showed a rapid rise in plasma cholesterol. Moreover, dietary restriction greatly enhanced the effect of the hypercholesterolemic diet which contained cholesterol and cholic acid. The major changes occurred in the very low density lipoprotein (VLDL) cholesterol which was increased in cholesterol-fed rats. This was amplified more than 2-fold by dietary restriction. In addition cholesterol feeding associated with dietary restriction induced a significant rise in the intermediate density lipoprotein (IDL)+low density lipoprotein (LDL) cholesterol. The findings indicate that dietary restriction could be an additional risk factor of hyperlipoproteinemia, specially when associated with high cholesterol intake.     

Plasma lipids, lipoproteins, and fecal excretion of neutral sterols and bile acids in rats fed various high fat diets or a low fat/high sucrose diet

The effect of feeding various diets on plasma lipids and lipoproteins and on fecal excretion of neutral sterols and bile acids was studied in rats fed for 7 wk diets containing 42% of energy as either coconut oil (CO), sunflower seed oil (SO), fish body oil (FBO), cod liver oil (CLO), or a low fat/high sucrose diet (SU). Triacylglycerols (TG) in whole plasma and VLDL + LDL were lower in rats fed high amounts of polyunsaturated fatty acids (PUFA) than in those fed the CO diet. Plasma HDL2 components in FBO and CLO groups were generally lower than in the other groups. Percentages of liver and heart linoleic and arachidonic acid were higher in the SO group, but lower in groups fed marine oils, than in the CO group. There was a high relative amount of eicosapentaenoic and docosahexaenoic acid in liver and heart of rats fed marine oils. Fecal excretion of bile acids was lower in the PUFA groups than in the CO group, whereas the sum of neutral sterols was similar in all groups. Plasma HDL2 (and VLDL + LDL) correlated positively, but HDL3 negatively, with fecal bile acid excretion. Accordingly, increased bile acid excretion does not seem to account for hypolipemia following intake of PUFA diets.     

Plasma lipoprotein cholesterol in rats fed a diet enriched in chitosan and cholesterol

To investigate the effect of dietary chitosan on plasma lipoprotein cholesterol metabolism, male Sprague-Dawley (SD) rats fed a cholesterol-enriched diet containing cellulose (CE) or chitosan (CS) were studied for 2 wk. Lower plasma total cholesterol, low-density lipoprotein (LDL) cholesterol and very-low-density lipoprotein (VLDL) cholesterol were observed in rats fed a diet containing chitosan. In addition, significantly higher high-density lipoprotein (HDL) cholesterol and HDL2 cholesterol were observed in rats after 2 wk of chitosan feeding. Rats fed the chitosan diet had increased triacylglycerol percentages and decreased free cholesterol, cholesteryl ester and phospholipid percentages in VLDL lipid composition. Chitosan significantly decreased the surface lipid proportions and increased the core lipid proportions in VLDL particles. In addition, the ratios of surface lipids to core lipids of the VLDL particles in rats fed a diet containing chitosan were significantly decreased. A significantly lower plasma apolipoprotein B (Apo B) concentration was observed in rats fed the chitosan diet as compared to those fed the cellulose diet. No significant difference in plasma triacylglycerols or glucose levels was observed between the two dietary groups. Results from this study suggest that chitosan may alter the VLDL particle size and also play an important role in the regulation of lipoprotein metabolism in rats.     

Studies of women eating diets with different fatty acid composition. I. Plasma lipoproteins and steroid excretion.

Moderate changes in dietary fat composition have been recommended to improve plasma cholesterol status. Such changes have not been studied extensively in women. This research evaluates plasma lipoprotein and steroid excretion changes in young women who consumed a diet similar to US average consumption in 1974 [40 en% fat, polyunsaturated (P) to saturated fatty acid (S) ratio, P/S = 0.3, US74] or a diet modified to contain 30 en% fat, P/S = 1.0 (MOD). Following a preexperimental period of self-selected diets, young women were fed the diets for 28-day periods in a crossover design with 10 women at the University of Nebraska, Lincoln, and 10 at Iowa State University, Ames. Plasma lipoproteins and steroid excretion were quantitated and the compositions determined. Data were analyzed for race (five Chinese, 14 Caucasians) and for diet carryover effects, as well as for primary diet effects. In the Chinese women, the US74 diet raised total and very-low-density lipoprotein (VLDL) cholesterol compared to prior self-selected or modified diets; in the Caucasian women the MOD diet lowered total, low-density lipoprotein (LDL), and VLDL cholesterol. The diet carryover was evident in total high-density lipoprotein (HDL) and HDL3 cholesterol. Total HDL and HDL3 cholesterol in response to the US74 diet were unchanged from the MOD diet when the US74 diet followed the MOD diet, but were lower than modified when the US74 diet followed self-selected diets. The US74 diet resulted in greater neutral sterol excretion than the MOD diet; this response was more marked in the self-selected, US74, MOD sequence than in the self-selected, MOD, US74 sequence.(ABSTRACT TRUNCATED AT 250 WORDS)     

Studies of women eating diets with different fatty acid composition. I. Plasma lipoproteins and steroid excretion

Moderate changes in dietary fat composition have been recommended to improve plasma cholesterol status. Such changes have not been studied extensively in women. This research evaluates plasma lipoprotein and steroid excretion changes in young women who consumed a diet similar to US average consumption in 1974 [40 en% fat, polyunsaturated (P) to saturated fatty acid (S) ratio, P/S = 0.3, US74] or a diet modified to contain 30 en% fat, P/S = 1.0 (MOD). Following a preexperimental period of self-selected diets, young women were fed the diets for 28-day periods in a crossover design with 10 women at the University of Nebraska, Lincoln, and 10 at Iowa State University, Ames. Plasma lipoproteins and steroid excretion were quantitated and the compositions determined. Data were analyzed for race (five Chinese, 14 Caucasians) and for diet carryover effects, as well as for primary diet effects. In the Chinese women, the US74 diet raised total and very-low-density lipoprotein (VLDL) cholesterol compared to prior self-selected or modified diets; in the Caucasian women the MOD diet lowered total, low-density lipoprotein (LDL), and VLDL cholesterol. The diet carryover was evident in total high-density lipoprotein (HDL) and HDL3 cholesterol. Total HDL and HDL3 cholesterol in response to the US74 diet were unchanged from the MOD diet when the US74 diet followed the MOD diet, but were lower than modified when the US74 diet followed self-selected diets. The US74 diet resulted in greater neutral sterol excretion than the MOD diet; this response was more marked in the self-selected, US74, MOD sequence than in the self-selected, MOD, US74 sequence.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of dietary fat saturation on plasma and hepatic lipoproteins in the rat

Semipurified diets containing 10% kilocalories from either safflower oil (SO), corn oil (CO), olive oil (OO) or palm oil (PO) were fed to weanling male rats for 2 weeks. The effects of dietary fat saturation on plasma lipids and lipoproteins were: 1) Nonfasted plasma cholesterol concentration was higher in rats fed OO (mean +/- SEM = 81.0 +/- 2.9 mg/dl) vs. CO (67.5 +/- 2.9); 2) plasma chylomicron cholesterol concentration was higher in rats fed OO vs. SO and CO, with PO values in between; and 3) the cholesterol concentration of plasma very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) did not differ among groups. The effects of dietary fat saturation on hepatic lipoproteins (determined by liver perfusion techniques) were: 1) hepatic higher density lipoprotein (d = 1.006-1.21 g/ml) cholesterol production was greater in rats fed SO and CO vs. PO [19.1 +/- 1.2, 17.2 +/- 0.8 and 13.7 +/- 1.6 micrograms/(g liver X 1.5 hour), respectively]; 2) there was no difference in hepatic VLDL cholesterol production among groups; and 3) the ratio of cholesterol to protein of hepatic VLDL and the higher density lipoprotein fraction was higher in rats fed diets rich in polyunsaturated fatty acids versus saturated fatty acids. Dietary fat saturation had no effect on carcass and liver cholesterol concentrations. Since differences in hepatic lipoprotein production were not reflected in plasma lipoprotein patterns, these results suggest that extrahepatic lipoprotein metabolism differs in rats fed diets containing fatty acids of varying saturation.     

Soluble oat fiber tends to normalize lipoprotein composition in cholesterol-fed rats

The effect of oat fiber on VLDL, LDL and HDL composition was investigated by feeding male Sprague-Dawley rats diets containing 1.0% cholesterol and 0.2% cholic acid, and 6% dietary fiber from oat bran, high-fiber oat flour or a processed oat product for 20 d. Compared to cholesterol-fed cellulose controls, all oat fibers altered the response to cholesterol feeding as indicated by 25-45% lower total lipoprotein cholesterol, 40-60% lower VLDL + LDL cholesterol, and 25-40% higher HDL cholesterol contents, P less than 0.01. The effect of the oat fibers on VLDL composition was especially pronounced as demonstrated by 30-65% lower VLDL protein, VLDL apo E and plasma apo B concentrations. The processed oat product which contained 40% more soluble fiber than oat bran or oat flour normalized the lipoprotein profile associated with ingestion of the atherogenic diet significantly more than oat bran or oat flour. Concentration of total lipoprotein cholesterol and distribution of apo E among the VLDL and LDL fractions in the processed oat product group were similar to controls not fed cholesterol. These data indicate that ingestion of oat fiber tends to normalize the lipoprotein profile induced by feeding an atherogenic diet in the rat, and that the hypocholesterolemic effect of oat fiber is associated with its soluble fiber content.     

Butter naturally enriched in conjugated linoleic acid and vaccenic acid alters tissue fatty acids and improves the plasma lipoprotein profile in cholesterol-fed hamsters

Butter, which is naturally enriched in cis-9, trans-11 conjugated linoleic acid (rumenic acid; RA) and vaccenic acid (VA), has been shown to be an effective anticarcinogen in studies with animal models; however, there has been no examination of the effects of a naturally derived source of VA and RA on atherosclerosis-related biomarkers. The current study was designed to determine the effect of a diet containing VA/RA-enriched butter on plasma lipoproteins and tissue fatty acid profiles in cholesterol-fed hamsters. Male Golden Syrian hamsters were fed diets containing 0.2% cholesterol and 20% added fat as: 1) Control, 20% standard butter (CT); 2) 5% standard butter + 15% VA/RA-enriched butter (EB); 3) 15% standard butter + 5% partially-hydrogenated vegetable oil (VO). After 4 wk, plasma lipoproteins were isolated, cholesterol quantified, and tissue fatty acid profiles determined. Tissue concentrations of VA and RA were increased by consumption of the EB diet compared with both the CT and VO diets, whereas the VO diet increased their concentration compared with the CT diet only. Total and LDL cholesterol concentrations were significantly reduced in hamsters fed EB and VO compared with CT, whereas VLDL cholesterol concentrations were reduced in hamsters fed EB compared with those fed CT and VO. HDL cholesterol concentrations did not differ among treatments. The ratio of potentially atherogenic lipoproteins [VLDL + intermediate density lipoproteins (IDL) + LDL] to antiatherogenic HDL was significantly lower in hamsters fed VA/RA-enriched butter (0.60) than in those fed either control diet (1.70) or the diet containing partially hydrogenated vegetable oil (1.04). Thus, increasing the VA/RA concentration of butter results in a plasma lipoprotein cholesterol profile that is associated with a reduced risk of atherosclerosis.     

Dietary grape seed tannins affect lipoproteins, lipoprotein lipases and tissue lipids in rats fed hypercholesterolemic diets

The effects of monomeric and polymeric grape seed tannins on rat plasma lipoproteins, lipoprotein lipase, hepatic lipase and aortic and hepatic lipid concentration were studied. Male Sprague-Dawley rats received either a normal diet (with no added cholesterol and no tannins), a control diet (hypercholesterolemic diet) or hypercholesterolemic diets supplemented with 2% tannin monomers or 2% polymers 3 or 9 wk. Plasma total cholesterol, triacylglycerol, LDL cholesterol and VLDL concentrations were significantly higher and the HDL cholesterol concentration lower in controls and in rats fed the diet supplemented with monomers compared with rats fed polymeric tannins at both time points. Lipoprotein lipase and hepatic lipase activities were significantly higher in control and in monomer-fed groups than in the polymer-fed group. Hepatic and aortic cholesterol and triacylglycerol concentrations were significantly higher in control rats and those fed monomers than in the polymer-fed group. Moreover, plasma HDL cholesterol and hepatic lipase activity were closely associated with low aortic cholesterol and triacylglycerol in rats fed polymeric tannins. These rats also exhibited greater fecal excretion of cholesterol and especially bile acids than the control or monomer-fed groups. Thus dietary grape seed tannins have a pronounced anti-hypercholesterolemic effect by enhancing reverse cholesterol transport and also by reducing intestinal cholesterol absorption and increasing bile acid excretion.     

Interrelationship of plasma triglycerides and HDL size and composition in rats fed different dietary saturated fats

We investigated the relative effects of different dietary saturated fats on the size distribution, apolipoprotein (apo) and chemical composition of HDL in fasted rats. Male Sprague-Dawley rats (174 +/- 2 g) were fed diets containing 0.035% cholesterol and 16% fat (wt/wt) from corn oil (CO diet) or from 2% CO plus 14% butterfat (BF diet), beef tallow (BT diet), palm oil (PO diet) or coconut oil (CN diet) for 6 wk. Apparent lipid digestibility was significantly lower with the PO and BT diets vs. the CO, BF and CN diets. Plasma total cholesterol levels were significantly higher in rats fed the PO and BT diets than in rats fed the BF and CN diets but were not different among the PO-, BT- and CO-fed groups. Nondenaturing gradient gel electrophoresis immunoblot analysis indicated that HDL apo A-I and E resided on particles with significantly smaller modal diameters in rats fed all saturated fats compared with those fed the CO diet. Chemical analyses indicated that HDL generally contained proportionately less protein and more triglyceride, free cholesterol and apo E with saturated fat feeding than with CO diet feeding. Significantly higher plasma and VLDL triglyceride levels were noted with ingestion of the BT, PO or CN diet than with the CO diet. Butterfat feeding resulted in lower plasma triglycerides and HDL-esterified cholesterol than did feeding the other saturated fats. Very low density lipoprotein triglyceride concentrations were inversely correlated with HDL modal diameter of apo E containing lipoproteins (P less than 0.005). These data provide further evidence of the interrelationship of triglyceride and HDL metabolism and suggest that mechanisms independent of cholesterol ester transfer protein may mediate this response in rats.     

Cholesterol concentration and lipoprotein pattern in the serum of veal calves fed milk replacers with various levels of cholesterol

Veal calves, aged about 1 week, were fed for 146 days milk replacement diets supplemented with various levels of cholesterol. Four groups consisting of 11 or 12 animals received diets to which 0, 0.19, 0.56 or 0.93% (on the basis of air-dry matter) cholesterol was added at the expense of fat. Cholesterol feeding significantly increased the level of serum cholesterol. This increase was either linear or S-shaped over the entire range of cholesterol feeding, depending on the time during which the calves were fed the diets. In the calves fed cholesterol, the ratio of free to esterified cholesterol in the serum was significantly increased. The ingestion of cholesterol markedly increased the cholesterol content of the VLDL, IDL and LDL fractions in the serum. When compared to the 0.56%-cholesterol diet, the inclusion of 0.93% cholesterol in the diet did not further increase the cholesterol concentrations in the IDL and LDL fractions. Upon density gradient ultracentrifugation of serum prestained for lipid with Sudan Black, it was observed that dietary cholesterol caused the HDL1 particles (1.063 less than d less than 1.092) to to shift towards a lower density range. Cholesterol feeding effected an increase in the level of serum triglycerides, the increase being already maximal with 0.19% cholesterol in the diet. Dietary cholesterol induced elevated concentrations of serum phospholipids, the elevation being proportional to the amount of cholesterol in the diet.     

Relative effects of dietary oleic- and linoleic-rich oils on plasma lipoprotein composition in rats

Plasma lipoprotein composition and hepatic lipid content were investigated in male Sprague-Dawley rats (104 +/- 2 g) fed diets containing 12% olive oil [OO, 70% 18:1(n-9)], 12% high oleic safflower oil [SO, 70% 18:(ln-9)] or 12% high linoleic safflower oil [SL, 73% 18:2(n-6)] for periods of up to 10 wk. Fasting plasma triglycerides were significantly higher after feeding oleic-rich diets than after feeding SL for 3, 5 and 6 wk. At 6 wk VLDL triglycerides were two- to threefold higher in rats fed OO or SO than in those fed SL, but by 10 wk both plasma and VLDL triglycerides were similar. A greater proportion of HDL2 (diameter 8.0-12.1 nm), a lower proportion of HDL1 (diameter 12.2-17.0 nm) and lower HDL apo E content occurred in rats fed OO and SO than in those fed SL at both 6 and 10 wk. LDL and HDL protein and cholesterol concentrations were not different with feeding SO or SL. After 10 wk of feeding the experimental diets, rats fed OO had significantly lower HDL protein, cholesterol and apo E concentrations and significantly higher hepatic triglyceride content compared to rats fed SO or SL, P less than 0.05. These data suggest that HDL and hepatic lipid content are determined by some property of the dietary oil other than its oleic acid content.     

Molasses increases HDL cholesterol in rats research note

Two experiments were conducted to determine whether molasses might exert effects on serum lipoproteins. In experiment 1, 24 rats were divided into two groups and fed diets containing liquid molasses from sugar beet or sucrose (7.71 g of molasses dry matter or sucrose per kg of diet). The second experiment included four groups of rats (n = l2/group) and was conducted in a bifactorial design, with the factors being molasses (non-supplementation vs. supplementation of 77.1 g of molasses dry matter per kg of diet at the expense of sucrose) and dietary cholesterol (0 vs. 5 g/kg diet). In experiment 1, the ratio of low-density lipoprotein (LDL) to high-density lipoprotein (HDL) cholesterol concentration tended to be lower in rats fed the molasses diet than in rats fed the control diet (p < 0.15). In experiment 2, rats fed the molasses diet had higher concentrations of HDL cholesterol (+ 26%) than control rats fed diets without molasses (p < 0.05). This effect was independent of the dietary cholesterol concentration. Concentrations of cholesterol in LDL, very low-density lipoprotein (VLDL), and liver as well as concentrations of triacylglycerols in plasma and liver remained unaffected by molasses in both experiments. In conclusion, the results of this study suggest that supplementation of molasses is effective at raising HDL cholesterol levels in rats.     

Beneficial effects of coconut water feeding on lipid metabolism in cholesterol-fed rats

The purpose of this study was to determine the effect of coconut water feeding in cholesterol-fed rats. Male albino rats were fed tender coconut water and mature coconut water at a dose level of 4 mL/100 g of body weight. Cholesterol feeding caused a marked increase in total cholesterol, very low-density lipoprotein (VLDL) + low-density lipoprotein (LDL) cholesterol, and triglycerides in serum. Administration of coconut water counteracts the increase in total cholesterol, VLDL + LDL cholesterol, and triglycerides, while high-density lipoprotein cholesterol was higher. Lipid levels in the tissues viz. liver, heart, kidney, and aorta were markedly decreased in cholesterol-fed rats supplemented with coconut water. Feeding coconut water resulted in increased activities of 3-hydroxy-3-methylglutaryl-CoA reductase in liver, lipoprotein lipase in heart and adipose tissue, and plasma lecithin:cholesterol acyl transferase, while lipogenic enzymes showed decreased activities. An increased rate of cholesterol conversion to bile acid and an increased excretion of bile acids and neutral sterols were observed in rats fed coconut water. Histopathological studies of liver and aorta revealed much less fatty accumulation in these tissues in cholesterol-fed rats supplemented with coconut water. Feeding coconut water resulted in increased plasma L-arginine content, urinary nitrite level, and nitric oxide synthase activity. These results indicate that both tender and mature coconut water has beneficial effects on serum and tissue lipid parameters in rats fed cholesterol-containing diet.     

Effects of dietary animal and plant proteins on the cholesterol metabolism in immature and mature rats

Three- and 9-mo-old rats were fed purified diets that contained either casein, cottonseed or soybean protein for 28 d, and plasma total and high density lipoprotein (HDL) cholesterol, lecithin cholesterol acyltransferase (LCAT) activity and excretion of fecal neutral sterols were measured. These analyses were performed in order to examine how various dietary proteins from animal and plant sources fed in a purified diet influence the changes in the cholesterol metabolism of the young and old rats. Both immature (3-mo-old) and mature (9-mo-old) rats fed purified diet containing casein maintained significantly higher plasma total and HDL cholesterol levels than their counterparts fed the same diets but containing plant proteins (soybean and cottonseed). The fractional rate of esterification (FR) of plasma free cholesterol in mature casein-fed rats was lower than that in immature rats. The FR was also lower in immature rats fed casein than in those fed plant protein. The net turnover rate (NR) of plasma cholesteryl esters (CE) tended to be higher in mature rats and in general was not affected by the dietary protein source. The rate of fecal excretion of neutral sterols was significantly higher in immature rats than in mature rats and in animals fed plant proteins at both ages than in those fed casein.     

Effects of addition of arginine, cystine, and glycine to the bovine milk-simulated amino acid mixture on the level of plasma and liver cholesterol in rats

The effects of the addition of varying levels of arginine (Arg), cystine (Cys), and glycine (Gly) to the bovine milk-simulated amino acid mixture on the levels of plasma and liver cholesterol were investigated in rats. The diets containing a high amount of Cys lowered significantly the level of plasma cholesterol as the amount of Cys in diets increased. The serum high density lipoprotein (HDL)-cholesterol level and fecal excretion of acidic steroids were higher in rats fed the Cys diets than in those fed the Arg and Gly diets. No differences, however, was observed in the content of liver cholesterol. Liver triglyceride contents elevated significantly on feeding the Arg and Cys diets. Furthermore, liver phospholipid contents elevated significantly on feeding the Arg diet but lowered on feeding the Cys diet. Therefore, these results indicated that the feeding of a high amount of Cys lowers the plasma cholesterol levels as the result of the enhanced conversion of cholesterol to bile acids.     

The effects of low cholesterol, high polyunsaturated fat, and low fat diets on plasma lipid and lipoprotein cholesterol levels in normal and hypercholesterolemic subjects

The effects of various cholesterol-lowering diets on plasma lipid and lipoprotein cholesterol levels were assessed in normal and hypercholesterolemic subjects. The base-line diet was an ad libitum hospital diet of normal composition. Diet A was a 20% protein, 40% carbohydrate, 40% fat, polyunsaturated:saturated fat ratio 0.1 to 0.3, 250 to 300 mg cholesterol diet, diet B was identical to diet A except that the polyunsaturated/saturated fat ratio was 1.8 to 2.2, and diet C was a 20% protein, 80% carbohydrate, very low fat (5 to 10 g), polyunsaturated/saturated fat ratio 0.1 to 0.3, 150 to 200 mg cholesterol diet. Diet A (low cholesterol) caused mean reductions in plasma, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol of 5.9, 5.6, and 6.3%, respectively, in 11 normal subjects. Diet B (low cholesterol, high polyunsaturated fat) caused significant decreases in plasma cholesterol, LDL cholesterol and HDL cholesterol of 17.0, 16.2, and 17.4%, respectively, in 12 normal subjects; and reductions of 11.0, 10.8, and 17.1%, respectively, in 19 hypercholesterolemic subjects. Diet C (low cholesterol, very low fat) produced significant mean decreases in plasma, LDL, and HDL cholesterol of 26.7, 29.9, and 27.9%, respectively, in 11 normal subjects, and in nine hypercholesterolemic patients of 22.6, 27.2, and 28.6%, respectively. The reductions in plasma cholesterol caused by these diets were therefore due to decreases in both LDL and HDL cholesterol with no significant changes in the LDL cholesterol:HDL cholesterol ratio.     

Effects of dietary methionine and glycine on serum lipoprotein profiles and fecal sterol excretion in normal and hepatoma-bearing rats

The effects of concurrent addition of methionine (Met) and glycine (Gly) to a 20% casein diet on serum lipoprotein profiles and fecal sterol excretion were studied in male Donryu rats with or without subcutaneous implantation of an ascites hepatoma line of AH109A cells. The hepatoma-bearing rats fed on the 20% casein diet had a notable elevation in the very-low-density lipoprotein + low-density lipoprotein (VLDL + LDL)-cholesterol (Ch) level with a slight but significant decrease in high-density lipoprotein (HDL)-Ch level when compared to the hepatoma-free (normal) rats fed on the same diet. The dietary addition of 1.2% Met and 2.5% Gly in combination suppressed the hepatoma-induced elevation in the (VLDL + LDL)-Ch level with a prevention of the hepatoma-induced decrease in the HDL-Ch level. The addition of the two amino acids also lowered significantly the (VLDL + LDL)-Ch level without affecting the HDL-Ch level in tumor-free rats. Fecal excretion of both neutral and acidic sterols were reduced with growth of the hepatoma. The dietary addition of Met and Gly exerted no or little influence on neutral sterol excretion in both the tumor-free and -bearing states, but it enhanced acidic sterol excretion into feces in both states, especially in the hepatoma-bearing state at the last stage of feeding. These results suggest that the excretion and catabolism of Ch might be impaired in hepatoma-bearing rats with growth of the tumor, and that the supplemental Met and Gly in combination might enhance Ch catabolism by stimulating either synthesis or conjugation of bile acids, leading to a reduction of the (VLDL + LDL)-Ch level in the normal and hepatoma-bearing states.     

The effect of dietary safflower phospholipid and soybean phospholipid on plasma and liver lipids in rats fed a hypercholesterolemic diet.

The effect of dietary safflower phospholipid (Saf-PL) and soybean phospholipid (Soy-PL) on plasma, liver, and fecal lipids in rats fed a hypercholesterolemic diet was compared with that of triglyceride mixture (controls). Triglyceride mixture (SP-Oil) of safflower oil and palm oil (8:2) contained almost comparable amounts of linoleic acid to safflower phospholipid or soybean phospholipid. Concentration of total cholesterol in plasma of rats fed the Saf-PL and Soy-PL diets were significantly decreased in comparison with that of the SP-Oil diet. Similarly, both Saf-PL and Soy-PL induced a reduction in the concentration of liver cholesterol compared with SP-Oil; Saf-PL indicated the lowest value. Saf-PL only significantly increased the level of high density lipoprotein (HDL) cholesterol. The level of chylomicron plus very low density lipoprotein (VLDL) cholesterol was lower in rats fed the Saf-PL and Soy-PL diets than that of the SP-Oil diet. The activity of plasma lecithin-cholesterol acyltransferase (LCAT) was increased in rats fed Saf-PL and Soy-PL. Saf-PL and Soy-PL caused an enhanced excretion of fecal neutral steroids, but not acidic steroids compared with SP-Oil. These results suggest that, in addition to soybean phospholipid, safflower phospholipid suppresses the elevation of plasma and liver cholesterol and that this effect may be brought about by inhibiting the absorption of cholesterol in the small intestine.