The APOB -516C/T polymorphism has no effect on lipid and apolipoprotein response following changes in dietary fat intake in a healthy population.

Our goal was to determine whether the presence of the -516C/T polymorphism in the APOB gene promoter modifies the lipid response to changes in the amount and quality of dietary fat. We studied 97 young healthy volunteers (70 males and 27 females), 62 homozygotes for the -516C allele (C/C) (47 males and 15 females), 34 heterozygotes for the -516T allele (C/T) (22 males and 12 females) and one male homozygote for the -516T allele (T/T). Subjects consumed three different diets in successive 4-week dietary periods. During the first 28 days, all subjects consumed a saturated fatty acid (SFA)-rich diet (38% fat and 20% SFA). Then, using a randomized crossover design, subjects were assigned a carbohydrate (CHO)-rich diet (30% fat and 55% carbohydrate) or a monounsaturated fatty acid (MUFA)-rich diet (38% fat and 22% MUFA). At the end of each dietary period, plasma concentrations of triacylglycerols and of total, LDL, and HDL cholesterol were measured. No differences in plasma lipid and apolipoprotein response were found after changes in dietary fat intake in relation to the -516C/T polymorphism in our study population. In conclusion, our data suggest that the APOB -516C/T polymorphism has no effect on the lipid profile after changes in dietary fat intake in a healthy population.

The chronic intake of a Mediterranean diet enriched in virgin olive oil, decreases nuclear transcription factor kappaB activation in peripheral blood mononuclear cells from healthy men.

OBJECTIVE: Nuclear transcription factor kappaB (NF-kappaB) plays a key role in the inflammatory response and can be modulate by dietary fat. We have examined the effect of three diets, with different fat composition, on the activation of NF-kappaB on peripheral blood mononuclear cells (PBMCs). METHODS: Sixteen healthy men followed three 4-week diets, in a randomised crossover design: a Western diet, rich in saturated fat (SFA) [22% SFA, 12% monounsaturated fat (MUFA) and 0, 4 alpha-linolenic acid]; a Mediterranean diet [<10% SFA, 24% MUFA and 0.4% alpha-linolenic acid], and a low fat diet enriched in alpha-linolenic acid [<10% SFA, 12% MUFA and 2% alpha-linolenic acid]. NF-kappaB (electrophoretic mobility shift assay) in mononuclear cells and plasma concentrations (ELISA) of soluble vascular cellular adhesion molecule 1 (VCAM-1) were examined after either diets. RESULTS: Western diet increased 2.7-fold NF-kappaB compared with the Mediterranean diet (p=0.038) and 1.79-fold with the alpha-linolenic acid diet (p=0.07). No differences were found between the last two. Furthermore, an increase on plasma VCAM-1 was observed with the Western diet (p<0.05). CONCLUSIONS: The Mediterranean diet diminished NF-kappaB activation in mononuclear cells, compared with Western diet, supporting its cardioprotective properties. The effect of the n-3 enriched diet was intermediate.

The Mediterranean and CHO diets decrease VCAM-1 and E-selectin expression induced by modified low-density lipoprotein in HUVECs.

BACKGROUND AND AIM: The oxidative modifications of low-density lipoprotein (LDL) are crucial for the atherosclerosis process. The aim of this study was to determine if the minimally modified LDL, obtained after the ingestion of three different diets, produce differential effects on the vascular cell adhesion molecule-1 (VCAM-1) and E-selectin expression in human umbilical endothelial cells (HUVECs). METHODS AND RESULTS: Twenty healthy young males were exposed to three dietary periods. Each period lasted four weeks. During the first period, all subjects consumed a saturated fat (SFA) enriched diet (38% fat, 20% SFA). The second and third dietary periods were administered following a randomized crossover design: a low fat high carbohydrates diet (CHO diet) and a Mediterranean diet. LDL particles, isolated during each dietary period, were oxidized by exposure to UV light and incubated for 48 h with HUVEC. Thereafter, 100 U/mL of TNF-alpha was added and incubation continued for 6 h. Cellular ELISA determined adhesion molecules expression. Lag time, propagation rate and total amounts of formed conjugated dienes were calculated in LDL incubated with 10mumol/L Cu(2+). When compared to the SFA diet, LDL isolated from the Mediterranean and CHO diets induced a lower expression of VCAM-1 and E-selectin in HUVECS (P<0.007). There were no differences between both lipid lowering diets. However, lag time of LDL from the Mediterranean diet was higher than with the CHO diet (P<0.042). This parameter was inversely correlated with E-selectin expression (r=-0.497; P<0.04). CONCLUSION: Our results suggest that both the Mediterranean and CHO diets may decrease the pro-inflammatory environment induced by modified LDL in endothelial cells.

A single nucleotide polymorphism of the apolipoprotein A-V gene -1131T>C modulates postprandial lipoprotein metabolism.

The Apolipoprotein A-V (apoA-V) gene promoter polymorphism -1131T>C modulates triacylglycerol (TG) concentrations. We evaluate whether this polymorphism could be involved in the interindividual variability observed during postprandial lipemia. Fifty-one healthy apo E3E3 male volunteers [12 with -1131CC/CT genotype, and 39 with -1131TT genotype] underwent a Vitamin A fat-load test consisting of 1g of fat/kg body weight and 60,000IU of Vitamin A. Blood samples were taken at time 0 and every hour until the 6th and every 2h and 30 min until the 11th. Cholesterol (Chol) and TG were determined in plasma and Chol, TG, ApoB-100, ApoB-48, and retinyl palmitate (RP) were determined in lipoprotein fractions. Data of postprandial lipemia revealed that subjects with the -1131CT/CC genotype had a higher postprandial response of total plasma TG (p=0.043), large triacylglycerol-rich lipoproteins-TG (TRL-TG) (p=0.002), large TRL-Chol (p=0.004), small TRL-Chol (p=0.004) and small TRL-RP (p=0.001) than subjects with the -1131TT genotype. The modifications observed in postprandial lipoprotein metabolism in subjects with the apoA-V -1131T>C polymorphism could be involved in the increased fasting plasma TG concentrations previously described in carriers of the C allele.

Phenolic content of virgin olive oil improves ischemic reactive hyperemia in hypercholesterolemic patients.

OBJECTIVES: The goal of this study was to evaluate the effects of the phenolic content of virgin olive oil on endothelial reactivity. BACKGROUND: Endothelial-dependent vasodilatation is impaired during the postprandial state, and oxidative stress could play a key role in its development. METHODS: Twenty-one hypercholesterolemic volunteers received two breakfasts, using a randomized sequential crossover design. Both arms received the same olive oil, but one had its phenolic acid content reduced from 400 to 80 ppm. Ischemic reactive hyperemia (IRH) was measured with a laser-Doppler procedure at baseline and 2 h and 4 h after oil intake. Postprandial plasma concentrations of lipid fractions, lipoperoxides (LPO), 8-epi prostaglandin-F(2alpha), and nitrates/nitrites (NO(x)) were obtained at baseline and after 2 h of the fat meal. RESULTS: The intake of the polyphenol-rich breakfast was associated with an improvement in endothelial function, as well as a greater increase in concentrations of NO(x) (p < 0.001) and a lower increase in LPO (p < 0.005) and 8-epi prostaglandin-F2alpha (p < 0.001) than the ones induced by the low polyphenol fat meal. A positive correlation was found to exist between NO(x) and enhanced endothelial function at the second hour (r = 0.669; p < 0.01). Furthermore, a negative correlation was found between IRH and LPO (r = -0.203; p < 0.05) and 8-epi prostaglandin-F2alpha levels (r = -0.440; p < 0.05). CONCLUSIONS: A meal containing high-phenolic virgin olive oil improves ischemic reactive hyperemia during the postprandial state. This phenomenon might be mediated via reduction in oxidative stress and the increase of nitric oxide metabolites.

The -514 C/T polymorphism in the hepatic lipase gene promoter is associated with insulin sensitivity in a healthy young population.

Impaired insulin action has been associated with diabetes, dyslipidemia and atherosclerotic vascular disease. The expression of insulin resistance results from the interaction of environmental and genetic factors. Human hepatic lipase (HL) is a lipolytic enzyme that plays a role in the metabolism of several lipoproteins, while insulin up-regulates the activity of HL via insulin-responsive elements in the HL promoter. We have examined the influence of -514 C/T polymorphism in the hepatic lipase gene promoter on insulin sensitivity in 59 healthy young subjects (30 males and 29 females). The volunteers were subjected to three dietary periods, each lasting four weeks. During the first period all subjects consumed a saturated fat (SFA)-enriched diet with 38% as fat (20% SFA, 12% monounsaturated fatty acids (MUFA) and 6% polyunsaturated fatty acids (PUFA)). In the second and third dietary periods, a randomized crossover design was used, consisting of a low fat, high carbohydrate diet (CHO diet) (< 10% SFA, 12% MUFA and 6% PUFA) and a high-MUFA, or Mediterranean diet, with < 10% SFA, 22% MUFA and 6% PUFA. We determined the in vivo insulin resistance using the insulin suppression test with somatostatin. Steady-state plasma glucose (SSPG) concentrations (a measure of insulin sensitivity) were significantly higher in men carriers of the -514T allele after the consumption of the SFA diet than after the CHO diet and the Mediterranean diet. This effect was not observed in women. Moreover, there were no significant differences in insulin sensitivity after the three diets in men and women with the CC genotype. In summary, our results show an improvement in insulin sensitivity in men with the -514T allele of the HL promoter polymorphism, when MUFA and carbohydrates are consumed instead of SFA fat.

A polymorphism exon 1 variant at the locus of the scavenger receptor class B type I (SCARB1) gene is associated with differences in insulin sensitivity in healthy people during the consumption of an olive oil-rich diet.

UNLABELLED: Scavenger receptor class B type I (SCARB1) was described as the first high-density lipoprotein receptor. Increasing evidence indicates that SCARB1 plays additional roles particularly in type 2 diabetes mellitus. Our aim was to determine whether the presence of an exon 1 (G-->A) polymorphism at the SCARB1 gene modifies the insulin sensitivity to dietary fat. METHODS: We studied 59 healthy volunteers (30 men and 29 women, 42 G/G homozygous and 17 G/A heterozygous). Subjects consumed three diets for 4 wk each: a saturated fatty acid (SFA)-rich diet (38% fat, 20% SFA), followed by a carbohydrate (CHO)-rich diet (30% fat, 55% CHO) or a monounsaturated fatty acid (MUFA)-rich diet (38% fat, 22% MUFA) after a randomized crossover design. For each diet, we investigated peripheral insulin sensitivity with the insulin suppression test. RESULTS: Steady-state plasma glucose after the MUFA diet was lower in G/A compared with G/G subjects (P = 0.030). This effect was not observed after CHO and SFA diets (P = 0.177 and 0.957, respectively). Plasma nonesterified free fatty acid values were lower in subjects carrying the A allele for all the diet periods. CONCLUSIONS: Our findings show that carriers of the G/A genotype have significant increases in insulin sensitivity after a MUFA-rich diet compared with G/G individuals.

Butter and walnuts, but not olive oil, elicit postprandial activation of nuclear transcription factor kappaB in peripheral blood mononuclear cells from healthy men.

BACKGROUND: Nuclear transcription factor kappaB (NF-kappaB) plays an important role in atherosclerosis by modulating gene expression. Postprandial lipemia has been correlated with an increase in NF-kappaB activation in vascular cells and it is associated with an increase in postprandial triacylglycerol-rich lipoproteins, which are involved in the development of atherosclerotic plaque. OBJECTIVE: The objective of this study was to determine the effect of the intakes of 3 different foods with different fat compositions on the postprandial activation of monocyte NF-kappaB. DESIGN: Eight healthy men followed a 4-wk baseline diet and then consumed 3 fat-load meals consisting of 1 g fat/kg body wt (65% fat) according to a randomized crossover design. Each meal had a different fatty acid composition, and the consumption of each meal was separated by 1 wk. The compositions of the 3 test meals were as follows: olive oil meal [22% saturated fatty acids (SFAs), 38% monounsaturated fatty acids (MUFAs), 4% polyunsaturated fatty acids (PUFAs), and 0.7% alpha-linolenic acid], butter meal (38% SFAs, 22% MUFAs, 4% PUFAs, and 0.7% alpha-linolenic acid), and walnut meal (20% SFAs, 24% MUFAs, 16% PUFAs, and 4% alpha-linolenic acid). RESULTS: Ingestion of the olive oil meal did not elicit NF-kappaB activation compared with ingestion of either the butter meal at 3 h (P <0.05) or the walnut meal at 9 h (P <0.05). There was no significant difference in the postprandial triacylglycerol response between the 3 meals. CONCLUSIONS: Consumption of an olive oil-enriched meal does not activate NF-kappaB in monocytes as do butter and walnut-enriched meals. This effect could enhance the cardioprotective effect of olive oil-enriched diets.

Apolipoprotein E gene promoter -219G->T polymorphism increases LDL-cholesterol concentrations and susceptibility to oxidation in response to a diet rich in saturated fat.

BACKGROUND: The apolipoprotein E (APOE) gene promoter polymorphism (-219G-->T) has been associated with increased risk of myocardial infarction, premature coronary artery disease, and decreased plasma apolipoprotein E concentrations. OBJECTIVE: We aimed to determine in healthy subjects whether this polymorphism modifies the susceptibility of LDL to oxidation and the lipid response to the content and quality of dietary fat. DESIGN: Fifty-five healthy men with the APOE3/E3 genotype (7 GG, 38 GT, and 10 TT) completed 3 dietary periods, each lasting 4 wk. The first was a saturated fatty acid (SFA)-rich diet [38% fat-20% SFA and 12% monounsaturated fatty acid (MUFA)-and 47% carbohydrates (CHO)], which was followed by a CHO-rich diet (30% fat-<10% SFA and 12% MUFA-and 55% CHO) or a MUFA-rich diet (38% fat-<10% SFA and 22% MUFA-and 47% CHO) in a randomized crossover design. At the end of each dietary period, LDL oxidation susceptibility, lipids, and lipoproteins were measured. RESULTS: Compared with carriers of the G allele, TT subjects had a significantly (P < 0.05) shorter lag time after the SFA diet. The replacement of the SFA diet by the CHO or MUFA diet induced a greater increase (P < 0.05) in lag time in the TT subjects than in the GG or GT subjects. Carriers of the T allele had higher LDL-cholesterol (P < 0.05) and apolipoprotein B (P < 0.05) plasma concentrations after the SFA diet than did GG subjects. Compared with GG subjects, carriers of the T allele had a significantly (P < 0.05) greater decrease in LDL cholesterol and apolipoprotein B when they changed from the SFA to the CHO diet. CONCLUSION: The -219G-->T polymorphism may partially explain differences in individual responses to diet.

The effect of dietary fat on LDL size is influenced by apolipoprotein E genotype in healthy subjects.

LDL particle size is dependent on both genetic factors and environmental factors such as dietary fat composition. The apolipoprotein E (apoE) genotype is a major genetic determinant of LDL size. Thus, the aim of this work was to study whether the apoE genotype interacts with the quantity and quality of dietary fat, modifying LDL size in young healthy subjects. Healthy subjects (n = 84; 66 apoE 3/3, 8 apoE 4/3, 10 apoE 3/2) were subjected to 3 dietary periods, each lasting 4 wk. The first was an SFA-enriched 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) following a randomized crossover design. At the end of each diet period, LDL particle size and plasma levels of total cholesterol, LDL cholesterol (LDL-C), HDL-C, apoB, apoA-I, and triacylglycerols were determined. LDL particle size was significantly higher (P < 0.04) in subjects with the apoE 4/3 genotype compared with those with apoE 3/3 and apoE 3/2 in the basal state. LDL size was smaller (P < 0.02) after the CHO diet than after the MUFA or SFA diets. After the CHO diet, a significant increase in LDL particle size (P < 0.035) was noted with respect to the MUFA diet in apoE 4/3 subjects, whereas a significant decrease was observed in the apoE 3/3 individuals (P < 0.043). In conclusion, a Mediterranean diet, high in MUFA-fat increases LDL particle size compared with a CHO diet, and this effect is dependent of apoE genotypes.

Influence of the -514C/T polymorphism in the promoter of the hepatic lipase gene on postprandial lipoprotein metabolism.

The -514C/T polymorphism located in the promoter region of the hepatic lipase gene mediates changes in the plasma levels of the enzyme. The aim of this study was to determine whether the presence of this polymorphism modifies the postprandial clearance of lipoproteins of intestinal origin. 51 normolipemic volunteers, homozygotes for the allele E3 of the apo E were selected (26 homozygotes for the C allele and 25 carriers of the T allele in both homozygote and heterozygote form). The subjects underwent a Vitamin A fat-loading test. Blood was drawn every hour until the 6th hour and every 2 h and 30 min until the 11th hour to determine cholesterol and plasma triglycerides as well as cholesterol, triglycerides (TG) and retinyl palmitate in triacylglycerol-rich lipoproteins (chylomicrons and chylomicron remnants). Carriers of the T allele showed significantly lower postprandial levels of apolipoprotein B (P < 0.01), total TG in plasma (P < 0.05), small TRL-TG (P < 0.04), large TRL-TG (P < 0.04) and small TRL-cholesterol (P < 0.04) when compared to subjects homozygous for the C allele. Our data suggest that the T allele of the -514C/T polymorphism in the promoter region of the hepatic lipase gene is associated with a lower postprandial lipemic response.