Low-fat and high-monounsaturated fatty acid diets decrease plasma cholesterol ester transfer protein concentrations in young, healthy, normolipemic men

BACKGROUND: Cholesterol ester transfer protein (CETP) mediates the transfer of cholesteryl esters from HDL to apolipoprotein (apo) B-containing lipoproteins. The possible atherogenic role of this protein is controversial. Diet may influence plasma CETP concentrations. OBJECTIVE: The objective was to determine whether the changes in plasma lipids observed after consumption of 2 lipid-lowering diets are associated with changes in plasma CETP concentrations. DESIGN:: We studied 41 healthy, normolipidemic men over 3 consecutive 4-wk dietary periods: a saturated fatty acid-rich diet (SFA diet: 38% fat, 20% saturated fat), a National Cholesterol Education Program Step I diet (NCEP Step I diet: 28% fat, 10% saturated fat), and a monounsaturated fatty acid-rich diet (MUFA diet: 38% fat, 22% monounsaturated fat). Cholesterol content (27.5 mg/MJ) was kept constant during the 3 periods. Plasma concentrations of total, LDL, and HDL cholesterol; triacylglycerol; apo A-I and B; and CETP were measured at the end of each dietary period. RESULTS: Compared with the SFA diet, both lipid-lowering diets significantly decreased plasma total and LDL cholesterol, apo B, and CETP. Only the NCEP Step I diet lowered plasma HDL cholesterol. Positive, significant correlations were found between plasma CETP and total (r = 0.3868, P < 0.0001) and LDL (r = 0.4454, P < 0.0001) cholesterol and also between changes in CETP concentrations and those of total (r = 0.4543, P < 0.0001) and LDL (r = 0.4554, P < 0.0001) cholesterol. CONCLUSIONS: The isoenergetic substitution of a high-saturated fatty acid diet with an NCEP Step I or a high-monounsaturated fatty acid diet decreases plasma CETP concentrations.     

The natural concentration of the conjugated linoleic acid, cis-9,trans-11, in milk fat has antiatherogenic effects in hyperlipidemic hamsters

Milk fat is usually considered to be proatherogenic, although its fatty acid composition can vary, due mainly to farming conditions. No study has evaluated whether such variation can modify the atherogenic properties of dairy fat. Aortic lipid deposition and related risk factors were examined in Syrian hamsters fed diets for 12 wk containing 200 g/kg of 2 commercial milk fats [high content of saturated fatty acids (HSF) and low content of saturated fatty acids (LSF)] contrasting, respectively, in total saturated fatty acids (72 vs. 67 g/100 g), 18:1, trans (4.24 vs. 7.26 g/100g), and conjugated linoleic acid (mainly cis-9,trans-11 or rumenic acid; 0.39 vs. 2.59 g/100 g). Hamsters fed the LSF-diet had 25% less aortic cholesteryl-ester deposition than those fed the HSF-diet; this was accompanied by an improved plasma cholesterol profile (lower LDL cholesterol and LDL:HDL cholesterol ratio), a lower local inflammatory status (aortic gene expression of cyclooxygenase-2), and lower aortic gene expression of vascular cell adhesion molecule-1 (all P < 0.05). Supplementation of the LSF-diet with rumenic acid (up to 9 g/kg) amplified the antiatherogenic effect of the original LSF-diet compared with the HSF-diet, i.e., less aortic cholesterol loading, increased reverse cholesterol transport potential (higher plasma HDL cholesterol concentration and ATP-binding cassette, subfamily A, transporter 1 gene expression in aorta), and decreased LDL-peroxidability index and gene expression of proinflammatory IL-1beta in the aorta (all P < 0.05). In conclusion, our results suggest that the atherogenic potential of milk fat can be greatly reduced in products with a naturally high abundance of rumenic acid, and argue for increasing this fatty acid in milk.     

Linoleic acid lowers LDL cholesterol without a proportionate displacement of saturated fatty acid

We tested the specificity of the plasma cholesterol-lowering effect of linoleic acid in a comparison of linoleate-rich and saturated fatty acid-rich foods. Twelve mildly hypercholesterolemic men and women ate the two diets for three weeks each in a random cross-over design, after a two-week baseline period. A linoleic acid-rich supplement was added to the baseline diet so that the saturated and monounsaturated fatty acid content did not change significantly. Despite the consequent increase in total fat intake, the linoleate-rich diet (23 per cent energy from polyunsaturated fatty acids) significantly lowered plasma total and low-density lipoprotein (LDL) cholesterol (-8 per cent and -14 per cent respectively), while high-density lipoprotein (HDL) cholesterol rose 8 per cent. The direction of these changes was similar in all 12 subjects. Compared with a supplement that raised dietary saturated fatty acids to 30 per cent energy, the linoleate acid-rich diet gave lower total cholesterol (-14 per cent), LDL cholesterol (-18 per cent) and HDL cholesterol (-12 per cent) concentrations. Linoleic acid lowers LDL cholesterol even when saturated fatty acids are not significantly displaced and substantially more when there is such displacement.     

Effect of dietary cholesterol in normolipidemic subjects is not modified by nature and amount of dietary fat

A double-blind, cross-over study of the effects of adding cholesterol to the diet, equal to about two egg yolks daily, was carried out in 25 men with an average plasma cholesterol of 5.3 mmol/L. There were no significant elevations in the mean plasma concentrations of cholesterol, low-density-lipoprotein cholesterol, or apolipoprotein B. The absence of an effect was seen against two background diets, one high in saturated fatty acids and the other modified in fat content and in fatty acid composition. Although the mean high-density-lipoprotein (HDL) cholesterol concentration did not change, the proportion of HDL2 particles (radius greater than 4.4 nm) increased significantly, especially in subjects who did not show a rise in plasma cholesterol; this may represent a means of clearing dietary cholesterol. The results suggest that reducing dietary cholesterol might be emphasized for hypercholesterolemic subjects rather than for the population generally.     

Low linolenate and commercial soybean oils diminish serum HDL cholesterol in young free-living adult females.

A mutant soybean line (A16) low in linolenic acid content (2% of oil by weight) was developed to increase oil oxidative stability. It was unknown whether serum lipid and lipoprotein concentrations in humans would be affected should A16 soybean oil (A16 oil) replace commercial soybean oil in diets. This study was conducted to examine the hypothesis that in free-living normolipidemic women, the consumption of A16 oil at approximately 10% of energy intake (en%) would not affect serum lipids and lipoproteins differently than would the consumption of the same amount of a commercial soybean oil with 7% of linolenic acid content.

Fifteen free-living female college students consumed the soybean oil daily with regular meals for 9 weeks in different orders, with each test oil being eaten for 3 weeks. During the study, 13 en% was provided by each test oil and a total of 35 en% was from dietary fat. Serum concentrations of total cholesterol, high-density lipoprotein cholesterol (HDL cholesterol), low-density lipoprotein cholesterol (LDL cholesterol) and triacylglycerides (TAG) were measured. Serum total fatty acid patterns were analyzed as well.

Each of the three test oils decreased serum total cholesterol, LDL cholesterol and TAG concentrations from the baseline values. The feeding of A16 and commercial soybean oils decreased serum HDL cholesterol significantly compared with coconut oil (p < 0.05). Dietary inclusion of coconut oil increased serum myristic acid significantly more than did either soybean oil (p < 0.01). Serum arachidonic acid concentrations were significantly greater with A16 consumption than with commercial soybean oil consumption (p < 0.001).

A16 and commercial soybean oils both diminished serum HDL cholesterol. Although the fatty acid composition differed between the two soybean oils, A16 oil and commercial oil had similar effects on serum concentrations of lipoproteins and lipids. With increased oxidative stability, A16 oil is a good alternative to commercial soybean oil.     

Difference in effect of myristic and stearic acid on plasma HDL cholesterol within 24 h in young men

BACKGROUND: There is increasing evidence that postprandial triacylglycerol (TAG)-rich lipoproteins (TRL) may be related to atherogenic risk. Little is known about the acute effect of individual dietary saturated fatty acids on plasma lipids and lipoproteins. OBJECTIVE: To investigate the effect of two prevalent dietary saturated fatty acids, stearic and myristic acid on postprandial and 24 h fasting plasma lipoprotein TAG and cholesterol concentrations. DESIGN: Ten young healthy men were served two meals (1.2 g fat/kg body weight) containing fat enriched in either stearic acid (S) (shea butter) or myristic acid (M) (produced by inter-esterification) in a randomised, cross-over study. The meals were given in the morning after 12 h of fasting and again after 8 h (in the afternoon). The S and M containing meals were given at different days separated by a washout period. Blood samples were taken before the meal and 2,4,6,8, and 24 h after the first meal. RESULTS: The M meal resulted in a higher postprandial HDL TAG response than S (P=0.03 I), (diet x time interaction), while no differences were observed in other lipid fractions. Twenty-four hours after the M meal fasting, HDL cholesterol was higher (P=0.05) and HDL TAG lower (P<0.001) than at baseline. CONCLUSIONS: Intake of individual dietary SFA may affect fasting HDL cholesterol within 24 h. Thus after this short period HDL cholesterol concentration was higher after myristic acid than stearic acid. Myristic acid resulted in a higher increase in postprandial HDL TAG than stearic acid.     

A diet containing rapeseed oil-based fats does not increase lipid peroxidation in humans when compared to a diet rich in saturated fatty acids

OBJECTIVE: To compare the effects of a rapeseed oil-based diet containing an increased proportion of easily oxidised polyunsaturated fatty acids such as alpha-linolenic acid with a diet rich in saturated fatty acids on the degree of lipid peroxidation in the human body. DESIGN: A randomised cross-over study. SUBJECTS AND INTERVENTIONS: Nineteen healthy moderately hyperlipidemic subjects (six women and 13 men, age 50+/-8 y and body mass index (BMI) 24.5+/-2.6 kg/m(2)) were given a rapeseed oil-based diet (RO) and a control diet (SAT) rich in saturated fatty acids during two consecutive 4 week periods separated by a 4 week wash-out period. Biomarkers of lipid peroxidation and antioxidants were analysed in plasma and urine. RESULTS: No significant differences in plasma or urinary levels of free 8-iso-prostaglandin F(2alpha), plasma total 8-iso-prostaglandin F(2alpha) plasma hydroperoxides or plasma malondialdehyde were observed between the RO and SAT diets (P=0.14-0.95). A higher concentration of serum gamma-tocopherol was detected after the RO diet compared to the SAT diet (P<0.001), whereas the serum alpha-tocopherol concentration and plasma antioxidative capacity did not differ between the two test diets. The total cholesterol, LDL cholesterol and LDL/HDL ratio were lower after the RO diet compared to the SAT diet (P<0.001), while HDL cholesterol and total triglyceride levels were similar after the two diets. CONCLUSION: These results suggest that a rapeseed oil-based diet rich in alpha-linolenic acid does not seem to increase the degree of lipid peroxidation in plasma and urine compared to a diet rich in saturated fats. This is possibly due to a sufficient content of antioxidants in the rapeseed oil diet to increase circulating concentrations of antioxidants that may protect unsaturated fatty acids from oxidation. SPONSORSHIP: Swedish Council for Forestry and Agricultural Research and Foundation for Geriatric Research.     

Contribution of postprandial lipemia to the dietary fat-mediated changes in endogenous lipoprotein-cholesterol concentrations in humans

BACKGROUND: Dietary fats alter LDL and HDL cholesterol while serving as precursors of postprandial triacylglycerol-rich lipoproteins (TRLs). OBJECTIVE: We hypothesized that the saturated fatty acid (SFA)-mediated increase and the polyunsaturated fatty acid (PUFA)-mediated decrease in endogenous lipoprotein cholesterol are promoted by postprandial TRLs. DESIGN: We performed a 16-d crossover diet study to examine the effect of PUFA-rich [ratio of PUFAs to SFAs (P:S) = 2.0] and SFA-rich (P:S = 0.25) diets on fasting and postprandial plasma lipid and lipoprotein-cholesterol concentrations in 16 normolipidemic subjects. RESULTS: Fasting plasma cholesterol decreased significantly after a PUFA-rich diet because of a decrease in LDL (-12.3%; P < 0.05) and HDL (-3.8%; NS), but did not change after an SFA-rich diet. The appearance of postprandial TRLs in plasma at 4 h was linked to a significant lowering of both LDL (-7.4%) and HDL (-4.8%) after a PUFA-rich diet; no such effect was observed after the SFA-rich diet. At 7 h, LDL and HDL cholesterol returned to near fasting concentrations without postprandial TRL accumulation after a PUFA-rich diet but with a significant postprandial TRL accumulation after an SFA-rich diet. Thus, the in vivo postprandial clearance of cholesterol in LDL+HDL was greater after a PUFA-rich diet than after an SFA-rich diet. The appearance of postprandial TRLs in plasma increased the cholesteryl ester transfer protein-mediated transfer of cholesteryl ester from LDL+HDL to TRLs in vitro without a significant influence from dietary fat. CONCLUSION: Dietary fat-mediated alterations in the rate of hepatic removal of postprandial TRLs, which carry cholesterol accepted from LDL+HDL via cholesteryl ester transfer protein in vivo, may contribute to the dietary fat-mediated change in endogenous lipoprotein cholesterol.     

Macadamia nut consumption lowers plasma total and LDL cholesterol levels in hypercholesterolemic men

This study was conducted to assess the cholesterol-lowering potential of macadamia nuts. Seventeen hypercholesterolemic men (mean age 54 y) were given macadamia nuts (40-90 g/d), equivalent to 15% energy intake, for 4 wk. Plasma total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and homocysteine concentrations and the fatty acid composition of plasma lipids were determined before and after treatment. Plasma MUFA 16:1(n-7), 18:1(n-7) and 20:1(n-9) were elevated after intervention with macadamia nuts. Plasma (n-6) and (n-3) PUFA concentrations were unaffected by macadamia nut consumption. Plasma total cholesterol and LDL cholesterol concentrations decreased by 3.0 and 5.3%, respectively, and HDL cholesterol levels increased by 7.9% in hypercholesterolemic men after macadamia nut consumption. Plasma triglyceride and homocysteine concentrations were not affected by treatment. Macadamia nut consumption was associated with a significant increase in the relative intake of MUFA and a reduced relative intake of saturated fatty acids and PUFA. This study demonstrates that macadamia nut consumption as part of a healthy diet favorably modifies the plasma lipid profile in hypercholesterolemic men despite their diet being high in fat.     

Palmitic and stearic acids similarly affect plasma lipoprotein metabolism in cynomolgus monkeys fed diets with adequate levels of linoleic acid

This study was designed to evaluate whether the exchange of specific saturated fatty acids [SFA; palmitic acid (16:0) for stearic acid (18:0)] would differentially affect plasma lipids and lipoproteins, when diets contained the currently recommended levels of total SFA, monounsaturated fatty acids and polyunsaturated fatty acids (PUFA). Ten male cynomolgus monkeys were fed one of two purified diets (using a cross-over design) enriched either in 16:0 (palmitic acid diet) or 18:0 (stearic acid diet). Both diets provided 30% of energy as fat (SFA/monounsaturated fatty acid/PUFA: 1/1/1). The palmitic acid and stearic acid diets were based on palm oil or cocoa butter (59% and 50% of the total fat, respectively). By adding different amounts of sunflower, safflower and olive oils, an effective exchange of 16:0 for 18:0 of approximately 5% of energy was achieved with all other fatty acids being held constant. Monkeys were rotated through two 10-wk feeding periods, during which time plasma lipids and in vivo lipoprotein metabolism (following the simultaneous injection of (131)I-LDL and (125)I- HDL were evaluated). Plasma triacyglycerol (0.40 +/- 0.03 vs. 0.37 +/- 0.03 mmol/L), plasma total cholesterol (3.59 +/- 0.18 vs. 3.39 +/- 0.23 mmol/L), HDL cholesterol (1.60 +/- 0.16 vs 1.53 +/- 0.16 mmol/L) and non-HDL cholesterol (2.02 +/- 0.26 vs. 1.86 +/- 0.23 mmol/L) concentrations did not differ when monkeys consumed the palmitic acid and stearic acid diets, respectively. Plasma lipoprotein compositional analyses revealed a higher cholesteryl ester content in the VLDL fraction isolated after consumption of the stearic acid diet (P < 0.10), as well as a larger VLDL particle diameter (16.3 +/- 1.7 nm vs. 13.8 +/- 3.6 nm; P < 0.05). Kinetic analyses revealed no significant differences in LDL or HDL transport parameters. These data suggest that when incorporated into diets following current guidelines, containing adequate PUFA, an exchange of 16:0 for 18:0, representing approximately 11 g/(d.10.46 mJ) [ approximately 11 g/(d.2500 kcal)] does not affect the plasma lipid profile and has minor effects on lipoprotein composition. Whether a similar effect would occur in humans under comparable dietary conditions remains to be established.     

Comparison between the effects of dietary saturated (16:0), monounsaturated (18:1), and polyunsaturated (18:2) fatty acids on plasma lipoprotein metabolism in cebus and rhesus monkeys fed cholesterol-free diets.

Cebus and rhesus monkeys were fed cholesterol-free diets providing 40% of energy as fat for 6-wk periods. The fats were high-linoleic acid safflower oil (HLSO), high-oleic acid safflower oil (HOSO), or palm oil (PO), rich in polyunsaturated (18:2), monounsaturated (18:1), or saturated (16:0) fatty acids, respectively. In cebus monkeys, plasma cholesterol concentrations during HLSO intake were 17-19% lower than those during HOSO or PO intake, attributed to a decrease in high-density lipoprotein (HDL). Plasma triglyceride (TG) and low-density-lipoprotein (LDL) cholesterol concentrations were comparable during all dietary treatments. Sixty-eight percent of total LDL catabolism was receptor mediated in all dietary groups and this was associated with similar apolipoprotein B pool sizes and fractional catabolic rates. Rhesus monkeys revealed similar cholesterol concentrations (total, LDL, and HDL) during all dietary treatments. TG concentrations during PO intake were 34% and 63% higher than those during HOSO and HLSO intakes, respectively. Hence, dietary 16:0 and 18:1 produce similar effects on LDL and HDL metabolism in normocholesterolemic primates.     

Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials

BACKGROUND: The effects of dietary fats on the risk of coronary artery disease (CAD) have traditionally been estimated from their effects on LDL cholesterol. Fats, however, also affect HDL cholesterol, and the ratio of total to HDL cholesterol is a more specific marker of CAD than is LDL cholesterol. OBJECTIVE: The objective was to evaluate the effects of individual fatty acids on the ratis of total to HDL cholesterol and on serum lipoproteins. DESIGN: We performed a meta-analysis of 60 selected trials and calculated the effects of the amount and type of fat on total:HDL cholesterol and on other lipids. RESULTS: The ratio did not change if carbohydrates replaced saturated fatty acids, but it decreased if cis unsaturated fatty acids replaced saturated fatty acids. The effect on total:HDL cholesterol of replacing trans fatty acids with a mix of carbohydrates and cis unsaturated fatty acids was almost twice as large as that of replacing saturated fatty acids. Lauric acid greatly increased total cholesterol, but much of its effect was on HDL cholesterol. Consequently, oils rich in lauric acid decreased the ratio of total to HDL cholesterol. Myristic and palmitic acids had little effect on the ratio, and stearic acid reduced the ratio slightly. Replacing fats with carbohydrates increased fasting triacylglycerol concentrations. CONCLUSIONS: The effects of dietary fats on total:HDL cholesterol may differ markedly from their effects on LDL. The effects of fats on these risk markers should not in themselves be considered to reflect changes in risk but should be confirmed by prospective observational studies or clinical trials. By that standard, risk is reduced most effectively when trans fatty acids and saturated fatty acids are replaced with cis unsaturated fatty acids. The effects of carbohydrates and of lauric acid-rich fats on CAD risk remain uncertain.     

Effects of butter high in ruminant trans and monounsaturated fatty acids on lipoproteins, incorporation of fatty acids into lipid classes, plasma C-reactive protein, oxidative stress, hemostatic variables, and insulin in healthy young men

BACKGROUND: Evidence suggests that ruminant trans fatty acids (FAs), such as vaccenic acid, do not increase the risk of ischemic heart disease (IHD). However, the effects of ruminant trans FAs on risk markers of IHD have been poorly investigated. OBJECTIVE: The objective was to investigate the effect of butter with a naturally high content of vaccenic acid and a concomitantly higher content of monounsaturated FAs on classic and novel risk markers of IHD. DESIGN: In a double-blind, randomized, 5-wk, parallel intervention study, 42 healthy young men were given 115 g fat/d from test butter that was high in vaccenic acid (3.6 g vaccenic acid/d) or a control butter with a low content of vaccenic acid. Blood and urine samples were collected before and after the intervention. RESULTS: The intake of the vaccenic acid-rich diet resulted in 6% and 9% lower total cholesterol and plasma HDL-cholesterol concentrations, respectively, than did the intake of the control diet (P = 0.05 and 0.002, respectively), whereas the ratio of total to HDL cholesterol did not differ significantly between the groups. The FA composition of lipid classes reflected the FAs' proportion of the test butter. No other differences were observed. CONCLUSIONS: Butter high in ruminant trans and monounsaturated FAs resulted in significantly lower total and HDL cholesterol than did the control butter with higher amounts of saturated FAs. It may be that the differences were due to the greater content of monounsaturated FAs and the lesser content of saturated FAs in the butter rich in ruminant trans FAs, rather than to the content of vaccenic acid per se.     

Polymorphism exon 1 variant at the locus of the scavenger receptor class B type I gene: influence on plasma LDL cholesterol in healthy subjects during the consumption of diets with different fat contents

BACKGROUND: The association between polymorphisms in the scavenger receptor class B type I (SRB-I) gene and variations in basal plasma concentrations of cholesterol in humans has recently been described. OBJECTIVE: The objective of the study was to determine whether the exon 1 variant (G-->A) at the SRB-I gene is associated with the lipid response to the content and quality of dietary fat in healthy subjects. DESIGN: We studied 97 healthy volunteers with exon 1 polymorphism [65 homozygous for allele 1 (1/1) and 32 heterozygous for allele 2 (1/2)]. Both groups consumed 3 diets lasting 4 wk each. The first was a saturated fatty acid (SFA)-rich diet (38% fat, 20% SFA), which was followed by a carbohydrate (Cho)-rich diet (30% fat, < 10% SFA, 55% carbohydrate) or a monounsaturated fatty acid (MUFA), olive oil-rich diet (38% fat, 22% MUFA) according to a randomized crossover design. At the end of each dietary period, plasma concentrations of triacylglycerol and of total, LDL, and HDL cholesterol were measured. RESULTS: Carriers of the 1/2 genotype had a trend toward higher concentrations of LDL cholesterol (P < 0.11) after the SFA-rich diet than did those who were homozygous for 1/1. Carriers of the mutation showed a significantly greater (P = 0.007) decrease in LDL-cholesterol concentrations (-23%) in changing from an SFA-rich diet to a Cho-rich diet than did noncarriers of the mutation (-16%). CONCLUSION: Carriers of the minority allele, 1/2, are more susceptible to the presence of SFA in the diet because of a greater increase in LDL cholesterol.     

Dietary polyunsaturated fatty acids enhance the uptake of high-density lipoprotein cholesterol ester by rat adipocytes

Compared with diets high in saturated and monounsaturated fatty acids (20% lard by weight), diets high in polyunsaturated fatty acids (20% sunflower oil) alter the fatty acid composition of rat adipocyte plasma membranes and enhance HDL2 binding. We examined the effect of these two diets on HDL1 and HDL2 apolipoprotein and cholesterol uptake by adipocytes isolated from perirenal and epididymal adipose tissue of male Wistar rats. Consistent with selective cellular uptake. HDL esterified cholesterol uptake was 3-10-fold higher than predicted from HDL apolipoproteins associated with adipocytes. Dietary polyunsaturated fatty acids significantly enhanced apolipoprotein and esterified-cholesterol uptakes from HDL2 by perirenal adipocytes. This effect of dietary fat composition was adipose-region (perirenal greater than epididymal) and HDL-subfraction (HDL2 greater than HDL1) specific. Thus, diet-induced changes known to alter membrane phospholipid composition and increase HDL2 binding are also associated with enhanced HDL2-esterified-cholesterol uptake by adipocytes.     

Effect of 6 dietary fatty acids on the postprandial lipid profile, plasma fatty acids, lipoprotein lipase, and cholesterol ester transfer activities in healthy young men

BACKGROUND: There is increasing evidence that postprandial triacylglycerol-rich lipoproteins may be related to atherogenic risk. OBJECTIVE: The objective was to investigate the effect of individual fatty acid intakes on postprandial plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acids, and preheparin lipoprotein lipase and cholesterol ester transfer protein (CETP) activities. DESIGN: Six test fats high (approximately 43% by wt) in stearic acid, palmitic acid, palmitic + myristic acid, oleic acid, elaidic acid (trans 18:1), and linoleic acid were produced by interesterification. After having fasted for 12 h, 16 healthy young men were served the individual test fats incorporated into meals (1 g fat/kg body wt) in random order on different days separated by washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after the meals. RESULTS: Different responses to the test-fat meals were observed for plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acid concentrations, and lipoprotein lipase and CETP activities (diet x time interaction: 0.001 < P < 0.05). Intake of the long-chain saturated fatty acids stearic and palmitic acids resulted in a relatively lower lipemic response than did intake of the unsaturated fatty acids, probably because the saturated fatty acids were absorbed less and at a lower rate; therefore, the lipemic response took longer to return to postabsorptive values. CONCLUSIONS: Fatty acid chain length and degree of saturation appear to affect the extent and duration of lipemia and affect hepatic output indirectly. These effects may not be mediated via effects on lipoprotein lipase and CETP activities.     

Relations between n-3 fatty acid status and cardiovascular disease risk factors among Quebecers.

BACKGROUND: Epidemiologic evidence shows an inverse relation between fish consumption and death from ischemic heart disease. This beneficial effect is attributed to n-3 fatty acids. OBJECTIVES: The purpose of this study was to examine the association between plasma phospholipid concentrations of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and various cardiovascular disease risk factors among Quebecers. DESIGN: The study population consisted of 1460 subjects aged 18-74 y who participated in the 1990 Quebec Heart Health and Nutrition Survey. Data were obtained through home interviews and clinic visits. RESULTS: Expressed as the percentage of total fatty acids in plasma phospholipids, the geometric means of EPA, DHA, and their combination were 0.47%, 1.19%, and 1.70%, respectively. Concentrations of n-3 fatty acids were positively associated with fish intake. We found positive associations between EPA and total cholesterol, LDL cholesterol, HDL cholesterol, plasma glucose, and systolic and diastolic blood pressure. We found positive associations between DHA and total cholesterol, the ratio of total to HDL cholesterol, triacylglycerols, systolic blood pressure, and plasma glucose and insulin. We also found positive associations between the ratio of EPA to arachidonic acid and total cholesterol, HDL cholesterol, and systolic blood pressure and a negative association with the ratio of total to HDL cholesterol. CONCLUSIONS: Our results indicate that concentrations of EPA and DHA in plasma phospholipids reflected Quebecer fish consumption. Results also show that EPA and the ratio of EPA to arachidonic acid can positively influence HDL-cholesterol concentrations.     

Pork with a high content of polyunsaturated fatty acids lowers LDL cholesterol in women

BACKGROUND: Animal products contribute significantly to the saturated fat and cholesterol content of the American diet. Contrary to dietary advice, consumers have not limited their consumption of animal products. Thus, an alternative approach might be to modify the fatty acid composition of animal products. OBJECTIVE: We tested the hypothesis that modified pork with a high content of polyunsaturated fatty acids (PUFAs) and a low content of saturated fatty acids (SFAs) would lower plasma LDL-cholesterol concentrations in women. DESIGN: Twenty women aged 19-24 y completed a crossover study with 2 diets. Nutritionally complete diets containing 42% of energy from fat differed only in the inclusion of either standard or modified pork. Venous blood samples were collected at weeks 0, 4, and 8. RESULTS: The diet containing modified pork significantly lowered total plasma (P < 0.0076) and LDL (P < 0.0382) cholesterol. The modified diet also resulted in an increase in the PUFA and a decrease in the SFA and monounsaturated fatty acid contents of the cholesteryl ester, free fatty acid, phospholipid, and triacylglycerol lipid classes in both plasma and erythrocytes. Plasma concentrations of glucose, insulin, triacylglycerol, and free fatty acids did not change significantly. CONCLUSIONS: Consumption of pork with a high PUFA content resulted in a decrease in the subjects' total plasma and LDL cholesterol and shifted the fatty acid composition from SFAs to PUFAs in the plasma and erythrocytes. Modification of the fatty acid composition of animal foods will be a useful approach to lowering the saturated fat consumption of Americans.     

Growth and lipid metabolism responses in rats fed different dietary fat sources

An experiment with male albino rats was conducted to examine the effect of dietary fat sources on growth performance and apparent digestibility of total fat and fatty acids. The effect on plasma and organ cholesterol concentrations as well as lipoproteins cholesterol and fatty acid profile of hepatic phospholipids was also examined. Forty 3 week old rats were fed purified diets containing 0.041% cholesterol and 7% fat (wt/wt) from soy oil (SO), or cow ghee (GH), or 25% fish oil (FO) plus soy oil (SF) or 25% fish oil plus 75% ghee (GF), or 50% soy oil plus 50% ghee (SG) for a period of 35 days. Final body weight, weight gain, organ weights and feed efficiency ratio showed no significant differences (P < 0.05) among the dietary treatments. The apparent digestibility of total dietary fat and saturated fatty acids in the animals fed diet containing cow ghee only or in combination with fish oil or soy oil was significantly lower than the other dietary groups. Consumption of ghee with combination of fish oil or soy oil lead to significant improvement in the fat apparent digestibility of dietary fat. Total cholesterol and triglyceride concentrations of plasma and organs as well as lipoprotein cholesterol levels were higher in animals fed diets containing ghee. For rats fed diet containing cow ghee in combination with fish oil or soy oil, the cholesterol content of total plasma, lipoprotein fractions (VLDL, LDL and HDL) and organs was decreased significantly. Furthermore, dietary fats altered the fatty acids composition of hepatic phosphlipid fatty acids composition. Feeding dietary fish oil reduced arachidonic acid (20:4) and increased linoleic acid (18:2) and eicosapentaenoic acid (20:5) contents. The reduction in the arachidonic acid was being more pronounced in animals fed dietary ghee with combination of fish oil.     

Growth and lipid metabolism responses in rats fed different dietary fat sources

An experiment with male albino rats was conducted to examine the effect of dietary fat sources on growth performance and apparent digestibility of total fat and fatty acids. The effect on plasma and organ cholesterol concentrations as well as lipoproteins cholesterol and fatty acid profile of hepatic phospholipids was also examined. Forty 3 week old rats were fed purified diets containing 0.041% cholesterol and 7% fat (wt/wt) from soy oil (SO), or cow ghee (GH), or 25% fish oil (FO) plus soy oil (SF) or 25% fish oil plus 75% ghee (GF), or 50% soy oil plus 50% ghee (SG) for a period of 35 days. Final body weight, weight gain, organ weights and feed efficiency ratio showed no significant differences (P < 0.05) among the dietary treatments. The apparent digestibility of total dietary fat and saturated fatty acids in the animals fed diet containing cow ghee only or in combination with fish oil or soy oil was significantly lower than the other dietary groups. Consumption of ghee with combination of fish oil or soy oil lead to significant improvement in the fat apparent digestibility of dietary fat. Total cholesterol and triglyceride concentrations of plasma and organs as well as lipoprotein cholesterol levels were higher in animals fed diets containing ghee. For rats fed diet containing cow ghee in combination with fish oil or soy oil, the cholesterol content of total plasma, lipoprotein fractions (VLDL, LDL and HDL) and organs was decreased significantly. Furthermore, dietary fats altered the fatty acids composition of hepatic phospholipid fatty acids composition. Feeding dietary fish oil reduced arachidonic acid (20:4) and increased linoleic acid (18:2) and eicosapentaenoic acid (20:5) contents. The reduction in the arachidonic acid was being more pronounced in animals fed dietary ghee with combination of fish oil.