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At least 145 records · Page 8Linked to original sources
PubMed1987

Influence of saturated and unsaturated fats on platelet fatty acids in cholesterol-fed rabbits.

Feeding natural fats varying in contents of palmitate (16:0), stearate (18:0), oleate (18:1), and linoleate (18:2) to rabbits resulted in modulation of platelet phospholipid fatty acyl composition. Rabbits were fed high fat semipurified diets containing 2% corn oil (CO) + 18% CO, cocoa butter (CB) or milkfat (M) for periods of up to 300 d. Platelet phospholipid linoleate contents corresponded to diet levels with 18:2 highest in CO-fed rabbits and following the sequence CO greater than CB greater than M. Stearate was highest in CB-fed rabbits, corresponding to high 18:0 levels in CB, but palmitate levels were not affected by diet. Both CB and M-fed rabbits were higher than CO-fed rabbits in oleate. Though CO is highest in 18:2, the accepted 20:4 precursor, arachidonate was highest in M-fed rabbits. Adding cholesterol (0.2%) to the diets did not affect platelet phospholipid fatty acyl composition except to elevate 20:4 in M-fed rabbits. CO-fed rabbits showed uniquely high levels of tetracosadienoate (24:2). Fatty acyl composition data were essentially constant between 200 and 300 d on diet. Phospholipid fatty acyl unsaturation was apparently homeostatically controlled as mole percent unsaturate to saturate ratios were independent of diet. The observed homeostasis resulted in minimal diet influences on platelet membrane fluidity and ADP or collagen stimulated platelet aggregation. Platelet fluidity, determined by fluorescence polarization, was a function of oleate and linoleate contents of the cells. Cholesterol feeding generally lowered platelet fluidity and altered the dependence of fluidity on fatty acyl composition.

Animals↗
PubMed1997

Coenzyme Q content depends upon oxidative stress and dietary fat unsaturation.

The presence of Coenzyme Q (CoQ) in food, its role in cellular bioenergetics and antioxidant protection and the key role played by dietary fatty acids on membrane structure support the interest for a wide research concerning the relationship between dietary fats, CoQ content and biochemical behaviour. Several models of peroxidative stress 'in vivo' have been extensively investigated in our laboratory, with particular regards to the influence of dietary fat upon mitochondrial CoQ levels. First studies showed that the unsaturation degree of dietary fat leads to different CoQ9 and CoQ10 mitochondrial contents. The highest levels were found using polyunsaturated fat. A significant CoQ9 decrease after adriamycin peroxidative induction was found when dietary fat was polyunsaturated; on the contrary, a light increase was found in the case of monounsaturated fat. Another example of oxidative stress is that produced by food frying. The results obtained were in some cases similar to those of the previous experimental design: in fact monounsaturated dietary fats increased CoQ mitochondrial contents, whereas the polyunsaturated ones decreased CoQ levels. Finally, the combined effect of physical exercise and dietary fats on tissue and plasma CoQ levels has been studied. CoQ levels did not change during aerobic performances when dietary fat was monounsaturated whereas light increases were detected in the case of polyunsaturated fats. On the contrary, in anaerobic conditions, CoQ levels clearly increased with monounsaturated fats and no alterations were found in the case of polyunsaturated ones.

Aerobiosis↗
PubMed1981

Effect of saturated and unsaturated fat diets on molecular species of phosphatidylcholine and sphingomyelin of human plasma lipoproteins.

Four healthy 21-23-year-old males with normal lipoprotein patterns and plasma lipid concentrations were subjected voluntarily to two diets of 5 weeks duration each: I, highly saturated fat diet; II, highly polyunsaturated fat diet. The VLDL, LDL and HDL3 fractions were isolated by conventional ultracentrifugation from each subject on the high fat diets and the molecular species of the component phosphatidylcholines and sphingomyelins were identified and quantitated by GC-MS of the t-butyldimethylsilyl ethers of the corresponding diacylglycerols and ceramides. It was shown that the diet markedly and rather evenly affected the molecular species of the phosphatidylcholines of all lipoprotein classes. However, the changes in the corresponding major molecular species were reciprocal in nature and were consistent with a demonstrated relative resistance to alterations in surface fluidity. In contrast, the dietary fat had only a minor effect on the composition of the sphingomyelins, and did not alter the characteristic differential distribution of the molecular species among the low and high density lipoprotein classes. These results, which were free of the uncertainties introduced by analyses of derived fatty acid and which were obtained on samples isolated from the same subjects, clearly demonstrate that a complete equilibration of the molecular species of the phospholipids is not attained amont the plasma lipoprotein classes even in the fasting state. The possible physico-chemical and metabolic basis of these observations is briefly discussed.

Adult↗
PubMed1984

Effect of trans-unsaturated fats on experimental atherosclerosis in vervet monkeys.

Vervet monkeys ( Ceropithecus aethiops pygerethrus ) were placed on semipurified diets containing 14% fat of which 3.2 or 6.0% was present as trans-unsaturated fatty acid (t-FA). Two groups were fed the high and low levels of t-FA for a year and two others were fed t-FA for 6 months and then returned to the control diet for 6 months more. One other group was fed the control diet for a year. The control diet contained 14% fat which was a mixture of 72% olive oil and 28% corn oil. There were no significant differences in weight gain. Monkeys fed 6% t-FA or control diets for one year had lowest liver weights. Serum cholesterol and triglycerides in monkeys fed 3.2% t-FA for one year were 134 and 55 mg/dl, respectively; in monkeys returned to control diet after 6 months on 6% t-FA the values were 146 and 50 g/dl. Serum and triglyceride levels for the other 3 groups were 166 +/- 2 and 70 +/- 2 mg/dl. Liver cholesterol levels ranged from 4.0 mg/g (3.2% t-FA) to 4.7 mg/g (control) and 4.8 mg/g (6% t-FA). Lecithin:cholesterol acyltransferase (LCAT) activity was 59.0 microM/h for controls and ranged from 52.4 microM/h (3.2% t-FA) to 73.4 microM/h (6% t-FA). Cholesterol synthesis by liver slices was not affected by diet when the substrate was acetate. When mevalonate was used, the monkeys fed either level of t-FA for 12 months exhibited greatly reduced (about 80%) cholesterogenesis. The levels of t-FA in serum and liver reflected the amount in the diet. After being returned to control diet levels of t-FA in serum and liver of monkeys (fed 3.2% t-FA) fell by 97 and 94%, respectively, and those in serum and liver of monkeys fed 6% t-FA fell by 65 and 91%. There were no significant differences in aortic atherosclerosis or arteriosclerosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Effect of dietary cholesterol and degree of fat unsaturation on plasma lipid levels, lipoprotein composition, and fecal steroid excretion in normal young adult men.

Effect of four test diets differing in the ratio of polyunsaturated to saturated fats (P/S, 1.8 vs 0.28) and two cholesterol levels (1,000 vs 300 mg/day) for each level of the P/S ratio was determined on plasma lipid levels, lipoprotein compositions and concentrations, and fecal steroid excretion in a controlled diet study with 11 normal young men using a crossover design. Plasma cholesterol levels were significantly decreased by the diets high in P/S ratio regardless of the dietary cholesterol levels (14% decrease by high cholesterol and 20% in low cholesterol) while the diets low in P/S ratio increased cholesterol by an average of 24 and 22% in presence of high and low cholesterol, respectively. Lipids and apoproteins of lower-density lipoproteins were changed in accordance with those of plasma cholesterol but changes in high-density lipoprotein (HDL) appear to depend on both cholesterol content and P/S ratio. Dietary cholesterol level profoundly influenced the excretion of neutral sterols and diets high in P/S ratio significantly (p less than 0.05) increased fecal bile acid extraction. The present study demonstrated that dietary polyunsaturated fats, when a moderate amount was consumed, were effective and beneficial hypocholesterolemic nutrients without reducing HDL-cholesterol.

Adult↗
PubMed2003

The serum LDL/HDL cholesterol ratio is influenced more favorably by exchanging saturated with unsaturated fat than by reducing saturated fat in the diet of women.

We compared the effects of a high fat diet [38.4% of energy (E%) from fat; HSAFA diet, polyunsaturated/saturated fatty acid (P/S) ratio = 0.14], a low fat diet (19.7 E% from fat; LSAFA diet, P/S = 0.17), both based on coconut oil, and a diet with a high content of mono- and polyunsaturated fatty acids (PUFA; 38.2 E% from fat; HUFA diet, P/S = 1.9) on serum lipoproteins. The 25 women studied consumed each diet for 3-wk periods in a crossover design. The two high fat diets were identical except for the quality of the test fat. The LSAFA diet was identical to the HSAFA diet except that half the fat was replaced by carbohydrates. Serum total cholesterol, LDL cholesterol and apoB concentrations did not differ between the HSAFA and the LSAFA diet periods. Total cholesterol, LDL cholesterol and apoB were lower when women consumed the HUFA diet than when they consumed the other two diets. HDL cholesterol and apoA-I were 15 and 11%, respectively, higher when women consumed the HSAFA diet than when they consumed the LSAFA diet; HDL cholesterol and apoA-I were lower when women consumed the HUFA diet than when they consumed the HSAFA diet, but not the LSAFA diet. The LDL cholesterol/HDL cholesterol and apoB/apoA-I ratios were higher when women consumed the LSAFA diet than when they consumed the HSAFA diet. The LDL/HDL cholesterol ratio was higher when women consumed either the LSAFA or the HSAFA diet than when they consumed the HUFA diet, whereas apoB/apoA-I was higher when women consumed the LSAFA diet than when they consumed the HUFA diet. Triacylglycerol and VLDL cholesterol were higher when women consumed the LSAFA diet than when they consumed either the HSAFA or the HUFA diet. We conclude that, to influence the LDL/HDL cholesterol ratio, changing the proportions of dietary fatty acids may be more important than restricting the percentage of total or saturated fat energy, at least when derived mainly from lauric and myristic acids, both of which increase HDL cholesterol.

Adult↗
PubMed1987

Effect of dietary lipids on inotropic responses of isolated rat left atrium: attenuation of maximal responses by an unsaturated fat diet.

The effect of varying the dietary fatty acid composition on inotropic responses to various pharmacological agents was investigated in isolated rat left atrium. Pregnant rats were fed either semisynthetic diets supplemented with coconut oil (saturated fatty acids), sunflower oil (unsaturated) or Purina Rodent Chow. Newborns were exposed through the maternal milk and later fed the same diets throughout adulthood. Sunflower oil caused a significant decrease in the maximal response of adult atria to norepinephrine, epinephrine and isoproterenol compared with the other diets. However, no differences in contractile response to norepinephrine were detected at ages 11 and 30 days, indicating a delayed onset of the response changes. We had previously demonstrated defects in the beta adrenoceptor-adenylate cyclase system in homogenates of atria from adult rats fed sunflower oil that may partly explain the attenuated adrenergic response. Additional inotropic studies were performed to further examine the role of this system. There was no change in the maximal contractile response to agents acting through cyclic AMP [cAMP (adenosine 3',5'-cyclic monophosphate)]-independent mechanisms, calcium and phenylephrine. In contrast, maximal responses to forskolin, 3-isobutyl-1-methylxanthine, and N6,2'-O-dibutyryl cAMP, which act via cAMP-dependent mechanisms, were significantly depressed by dietary sunflower oil. No differences were detected in cAMP hydrolysis by phosphodiesterase. These data are consistent with the hypothesis that alterations in adrenergic responsiveness of rat atria after dietary lipid treatment involve functional changes in the adenylate cyclase pathway distal to the enzyme.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Should mono- or poly-unsaturated fats replace saturated fat in the diet?

The effects of diets differing in saturated, monounsaturated and polyunsaturated fatty acid composition (SAFA, MUFA and PUFA, respectively) on plasma lipoproteins and factor VIIc were investigated in 28 middle-aged men and women with mild to moderate hyperlipidaemia. The subjects were stabilized on a diet with a total fat content fairly typical of New Zealand, containing approximately 40% energy as fat, before entering a randomized cross-over trial of diets high in PUFA (20% energy; SAFA and MUFA 10% each) or a high MUFA diet (20% energy; SAFA and PUFA 10% each). After 6-week periods on each diet the subjects returned to a high SAFA diet. Body weight and blood pressure remained unchanged during the study. Total and LDL cholesterol, HDL cholesterol and the HDL2 subfraction were significantly lower on both the MUFA and the PUFA diet than on SAFA. However, there were no statistically significant differences in lipoprotein concentrations on the MUFA and PUFA diet. Factor VIIc concentrations were similar on the three diets. The proportion of PUFA in a MUFA diet appears to be a major determinant of the relative lipoprotein response to such a diet. In order to avoid a reduction in HDL-C when replacing SAFA with MUFA it may be necessary to ensure that PUFA does not provide more than about 8% total energy. Thus careful planning is needed to identify the most appropriate foods to replace those rich in SAFA in diets designed to reduce the lipoprotein-mediated risk of coronary heart disease.

Aged↗
PubMed1977

Lecithin: cholesterol acyl transferase activity in the serum of rats fed saturated and unsaturated fats.

Groups of rats were fed diets containing either butter, beef, fat or safflower oil. After 20 or 70 days of feeding, blood was taken from the animals in a postabsorptive state. Serum lipid levels and lecithin: cholesterol acyl transferase activity were measured. Feeding the different fats did not alter serum total cholesterol levels but free cholesterol and triglycerides were significantly lower in the safflower oil-fed group. Net cholesterol esterification in vitro was also significantly depressed in the safflower oil-fed group and this was shown to be due to the inability of the lipoprotein substrate to support the reaction rather than because of low LCAT enzyme activity.

Acyltransferases↗
PubMed2002

Dietary fat, fat subtypes, and breast cancer risk: lack of an association among postmenopausal women with no history of benign breast disease.

A recent study among 13,707 postmenopausal women without benign breast disease (BBD) from the Breast Cancer Detection Demonstration Project (BCDDP) cohort found breast cancer risk associated with greater total fat, unsaturated fat, and oleic acid intake. We assessed the associations between cumulative averaged dietary intake from 1980, 1984, 1986, and 1990 with breast cancer risk through 1994 among 44,697 postmenopausal participants without BBD in the Nurses' Health Study (NHS). Multivariate Cox proportional hazard models, with age as the time variable, provided the estimated rate ratios (RRs) with 95% confidence intervals (CIs) from the 14 years of follow-up and the 1,071 breast cancer cases. In the Nurses' Health Study, breast cancer rates over the time period from 1980 to 1994 did not increase significantly with greater total fat [quintile (Q) 5 versus Q1 RR, 0.94; 95% CI, 0.77-1.15], saturated fat (RR(Q5 to Q1), 0.88; 95% CI, 0.70-1.12), unsaturated fat (RR(Q5 to Q1), 1.16; 95% CI, 0.92-1.46), oleic acid (RR(Q5 to Q1), 1.13; 95% CI, 0.81-1.57), linoleic acid (RR(Q5 to Q1), 0.93; 95% CI, 0.74-1.16), trans fatty acid (RR(Q5 to Q1), 0.9184; 95% CI, 0.73-1.13), or energy intake (RR(Q5 to Q1), 0.81; 95% CI, 0.67-0.99). A parallel analysis restricted to the same time period as the BCDDP study did not differ substantially. We found no increase in the rate of breast cancer with greater intake of dietary fat and fat subtypes among postmenopausal women without a history of BBD.

Adult↗