Plasma cholesteryl ester transfer protein activity is increased when trans-elaidic acid is substituted for cis-oleic acid in the diet

Association of dyslipidemia with single nucleotide polymorphisms of the cholesteryl ester transfer protein gene and cardiovascular disease risk factors in a highly admixed population

BACKGROUND AND AIMS

Cardiovascular diseases (CVD) are major causes of mortality worldwide, leading to premature deaths, loss of quality of life, and extensive socioeconomic impacts. Alterations in normal plasma lipid concentrations comprise important risk factors associated with CVD due to mechanisms involved in the pathophysiology of atherosclerosis. Genetic markers such as single nucleotide polymorphisms (SNPs) are known to be associated with lipid metabolism, including variants in the cholesteryl ester transfer protein (CETP) gene. Thus, the study's objective was to assess the relationship among lipid profile, socioeconomic and demographic characteristics, health status, inflammatory biomarkers, and CETP genetic variants in individuals living in a highly admixed population.

METHODS

The study comprises an analysis of observational cross-sectional data representative at the population level from a highly admixed population, encompassing 901 individuals from three age groups (adolescents, adults, and older adults). Socioeconomic, demographic, health, and lifestyle characteristics were collected using semi-structured questionnaires. In addition, biochemical markers and lipid profiles were obtained from individuals' blood samples. After DNA extraction, genotyping, and quality control according to Affymetrix's guidelines, information on 15 SNPs in the CETP gene was available for 707 individuals. Lipid profile and CVD risk factors were evaluated by principal component analysis (PCA), and associations between lipid traits and those factors were assessed through multiple linear regression and logistic regression.

RESULTS

There were low linear correlations between lipid profile and other individuals' characteristics. Two principal components were responsible for 80.8 % of the total variance, and there were minor differences in lipid profiles among individuals in different age groups. Non-HDL-c, total cholesterol, and LDL-c had the highest loadings in the first PC, and triacylglycerols, VLDL-c and HDL-c were responsible for a major part of the loading in the second PC;, whilst HDL-c and LDL-c/HDL-c ratio were significant in the third PC. In addition, there were minor differences between groups of individuals with or without dyslipidemia regarding inflammatory biomarkers (IL-1β, IL- 6, IL-10, TNF-α, CRP, and MCP-1). Being overweight, insulin resistance, and lifestyle characteristics (calories from solid fat, added sugar, alcohol and sodium, leisure physical activity, and smoking) were strong predictors of lipid traits, especially HDL-c and dyslipidemia (p < 0.05). The CETP SNPs rs7499892 and rs12691052, rs291044, and rs80180245 were significantly associated with HDL-c (p < 0.05), and their inclusion in the multiple linear regression model increased its accuracy (adjusted R2 rose from 0.12 to 0.18).

CONCLUSION

This study identified correlations between lipid traits and other CVD risk factors. In addition, similar lipid and inflammatory profiles across age groups in the population suggested that adolescents might already present a significant risk for developing cardiovascular diseases in the population. The risk can be primarily attributed to decreased HDL-c concentrations, which appear to be influenced by genetic factors, as evidenced by associations between SNPs in the CETP gene and HDL-c concentrations, as well as potential gene-diet interactions. Our findings underscore the significant impact of genetic and lifestyle factors on lipid profile within admixed populations in developing countries.

A Review of Low-Density Lipoprotein-Lowering Diets in the Age of Anti-Sense Technology

This narrative review discusses an important issue, the primary role of diet in reducing low-density lipoprotein cholesterol (LDLc) concentrations in polygenic hypercholesterolemia. Two effective drugs, statins, and ezetimibe, that lower LDLc > 20% are relatively inexpensive and potential competitors to strict dieting. Biochemical and genomic studies have shown that proprotein convertase subtilisin kexin type 9 (PCSK9) plays an important role in low-density lipoprotein (LDL) and lipid metabolism. Clinical trials have demonstrated that inhibitory monoclonal antibodies of PCSK9 dose-dependently lower LDLc up to 60%, with evidence of both regression and stabilization of coronary atherosclerosis and a reduction in cardiovascular risk. Recent approaches using RNA interference to achieve PCSK9 inhibition are currently undergoing clinical evaluation. The latter presents an attractive option of twice-yearly injections. They are, however, currently expensive and unsuitable for moderate hypercholesterolemia, which is largely due to inappropriate patterns of eating. The best dietary approach, the substitution of saturated fatty acids by polyunsaturated fatty acids at 5% energy, yields > 10% lowering of LDLc. Foods such as nuts and brans, especially within a prudent, plant-based diet low in saturates complemented by supplements such as phytosterols, have the potential to reduce LDLc further. A combination of such foods has been shown to lower LDLc by 20%. A nutritional approach requires backing from industry to develop and market LDLc-lowering products before pharmacology replaces the diet option. Energetic support from health professionals is vital.

Modification of High-Density Lipoprotein Functions by Diet and Other Lifestyle Changes: A Systematic Review of Randomized Controlled Trials

High-density lipoprotein (HDL) functional traits have emerged as relevant elements that may explain HDL antiatherogenic capacity better than HDL cholesterol levels. These properties have been improved in several lifestyle intervention trials. The aim of this systematic review is to summarize the results of such trials of the most commonly used dietary modifications (fatty acids, cholesterol, antioxidants, alcohol, and calorie restriction) and physical activity. Articles were screened from the Medline database until March 2021, and 118 randomized controlled trials were selected. Results from HDL functions and associated functional components were extracted, including cholesterol efflux capacity, cholesteryl ester transfer protein, lecithin-cholesterol acyltransferase, HDL antioxidant capacity, HDL oxidation status, paraoxonase-1 activity, HDL anti-inflammatory and endothelial protection capacity, HDL-associated phospholipase A2, HDL-associated serum amyloid A, and HDL-alpha-1-antitrypsin. In mainly short-term clinical trials, the consumption of monounsaturated and polyunsaturated fatty acids (particularly omega-3 in fish), and dietary antioxidants showed benefits to HDL functionality, especially in subjects with cardiovascular risk factors. In this regard, antioxidant-rich dietary patterns were able to improve HDL function in both healthy individuals and subjects at high cardiovascular risk. In addition, in randomized trial assays performed mainly in healthy individuals, reverse cholesterol transport with ethanol in moderate quantities enhanced HDL function. Nevertheless, the evidence summarized was of unclear quality and short-term nature and presented heterogeneity in lifestyle modifications, trial designs, and biochemical techniques for the assessment of HDL functions. Such findings should therefore be interpreted with caution. Large-scale, long-term, randomized, controlled trials in different populations and individuals with diverse pathologies are warranted.

Antiproliferative Properties of Papaver rhoeas Ovule Extracts and Derived Fractions Tested on HL60 Leukemia Human Cells

Papaver rhoeas plant is common in many regions worldwide and contributes to the landscape with its red flower. In the present study we first carried out morphological investigation by optical and scanning electron microscopy of the ovules within the ovary. After ovules' isolation we prepared extracts to test possible cytotoxic activities on HL60 leukemia human cells and investigated the extracts using thin-layer chromatography (TLC) and gas-chromatography/mass spectrometry (GC-MS). P. rhoeas ovules showed an elongated, round shape and the presence of ordered sculptures on the ovule surface. The ovule extracts showed cytotoxic activity on HL60 human cells mainly found in some TLC-isolated spots. Compounds consisting of active spots were identified by GC-MS investigations. Our findings on the P. rhoeas ovule compounds open perspectives for further investigations of TLC-isolated spots on other human cancer cell lines.

Characterisation of Formaggella della Valle di Scalve Cheese Produced From Cows Reared in Valley Floor Stall or in Mountain Pasture: Fatty Acids Profile and Sensory Properties

An important problem in mountain areas is the abandonment of pasture. This trend can be combated by the valorisation of typical dairy products, such as “Formaggella della Valle di Scalve”, a semi-cooked traditional cheese made from whole milk in a mountain area in Italy. The aim of the present research was to compare the fatty acid (FA) profile and the sensory properties of this cheese as manufactured under different conditions: i) from the milk of cows grazing on mountain or valley pasture or fed indoors; ii) from the milk of cows fed hay or fed silage. In the first case, five cheesemaking trials were conducted during two years for each of the following situations: mountain pasture (A); pasture at the bottom of the valley (P) (about 1000m asl); stall (S). In the second case, three cheesemaking trials were conducted for each of the following situations: cows fed silage (I); cows fed hay (F). S cheese was richer in medium-chain FAs, while long-chain FAs were higher in P and A cheeses. On the other hand, long chain fatty acids (LCFA) were more abundant in P and A cheeses than in S. In general, MUFA, PUFA and, consequently, total unsaturated FA (UFA), were significantly higher in the P and A cheeses than S (UFA: 36.55 and 38.34, respectively, vs. 31.13; p < 0.001), while SFA showed higher values in S (68.85 vs. 63.41 and 61.68 in P and A, respectively; p < 0.001). Conjugated linoleic acid isomers (CLA) were more represented in the P and A samples (1.86 in P and 1.52 in A, vs. 0.80 in S; p < 0.001); Omega 3 fatty acids, and in particular α-linolenic acid, were more abundant in P than in S cheese. In winter, the I sample (silage) presented higher percentages of myristic (C14), myristoleic (C14:1) and omega 6 acids, whereas F cheese (hay) contained higher concentrations of CLA. The triangular test of sensory analysis showed that, in general, F cheeses were judged as “sweeter” than I, with aromatic profiles characterized by higher content of 2- butanol and ethyl capronate.

Buddleja saligna Willd (Loganiaceae) inhibits angiotensin-converting enzyme activity in oxidative cardiopathy with concomitant modulation of nucleotide hydrolyzing enzymatic activities and dysregulated lipid metabolic pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Buddleja saligna Willd (Loganiaceae), mostly indigenous to South Africa is traditionally used in the treatment cardio-dysfunctional related ailments amongst other diseases.

AIMS

The cardio-protective effect of B. saligna was investigated in ferric-induced oxidative cardiopathy.

METHODS

Hearts harvested from healthy male SD rats were incubated with 0.1 mM FeSO₄ to induce oxidative damage and co-incubated with B. saligna extract. Reaction mixtures without the extract served as negative control, while tissues without the extract or standard antioxidant (gallic acid) and pro-oxidant served as the normal control. The tissues were analyzed for levels of glutathione, malondialdehyde, and nitric oxide as well as cholinergic, angiotensin-converting enzyme (ACE), lipase, and purinergic enzymes activities, lipid profiles, fatty acid metabolic pathways and metabolites.

RESULTS

Induction of oxidative damage significantly (p < 0.05) depleted the levels of GSH, SOD, catalase, and ENTPDase activities, while concomitantly elevating the levels of MDA, NO, ACE, acetylcholinesterase, lipase and ATPase activities. These levels and activities were significantly reversed on treatment with B. saligna. Treatment with B. saligna also led to depletion of cardiac cholesterol and LDL-c levels, while elevating triglyceride and HDL-c level. It also depleted oxidative-induced lipid metabolites with concomitant generation of thirteen other metabolites. B. saligna also inactivated oxidative-induced pathways for beta oxidation of very long chain fatty acids, glycerolipid metabolism, and fatty acid elongation in mitochondria.

CONCLUSION

These results suggest that B. saligna protects against ferric-induced oxidative cardiopathy by mitigating oxidative stress, while concomitantly inhibiting ACE, acetylcholinesterase and lipase activities, and modulating lipid spectrum and dysregulated metabolic pathways.

Intermittent Hypoxia and Hypercapnia, a Hallmark of Obstructive Sleep Apnea, Alters the Gut Microbiome and Metabolome

Intestinal dysbiosis mediates various cardiovascular diseases comorbid with OSA. To understand the role of dysbiosis in cardiovascular and metabolic disease caused by OSA, we systematically study the effect of intermittent hypoxic/hypercapnic stress (IHH, mimicking OSA) on gut microbes in an animal model. We take advantage of a longitudinal study design and paired omics to investigate the microbial and molecular dynamics in the gut to ascertain the contribution of microbes on intestinal metabolism in IHH. We observe microbe-dependent changes in the gut metabolome that will guide future research on unrecognized mechanistic links between gut microbes and comorbidities of OSA. Additionally, we highlight novel and noninvasive biomarkers for OSA-linked cardiovascular and metabolic disorders.

Obstructive sleep apnea (OSA) is a common disorder characterized by episodic obstruction to breathing due to upper airway collapse during sleep. Because of the episodic airway obstruction, intermittently low O₂ (hypoxia) and high CO₂ (hypercapnia) ensue. OSA has been associated with adverse cardiovascular and metabolic outcomes, although data regarding potential causal pathways are still evolving. As changes in inspired O₂ and CO₂ can affect the ecology of the gut microbiota and the microbiota has been shown to contribute to various cardiometabolic disorders, we hypothesized that OSA alters the gut ecosystem, which, in turn, exacerbates the downstream physiological consequences. Here, we model human OSA and its cardiovascular consequence using Ldlr^−/− mice fed a high-fat diet and exposed to intermittent hypoxia and hypercapnia (IHH). The gut microbiome and metabolome were characterized longitudinally (using 16S rRNA amplicon sequencing and untargeted liquid chromatography-tandem mass spectrometry [LC-MS/MS]) and seen to covary during IHH. Joint analysis of microbiome and metabolome data revealed marked compositional changes in both microbial (>10%, most remarkably in Clostridia) and molecular (>22%) species in the gut. Moreover, molecules that altered in abundance included microbe-dependent bile acids, enterolignans, and fatty acids, highlighting the impact of IHH on host-commensal organism cometabolism in the gut. Thus, we present the first evidence that IHH perturbs the gut microbiome functionally, setting the stage for understanding its involvement in cardiometabolic disorders.

IMPORTANCE Intestinal dysbiosis mediates various cardiovascular diseases comorbid with OSA. To understand the role of dysbiosis in cardiovascular and metabolic disease caused by OSA, we systematically study the effect of intermittent hypoxic/hypercapnic stress (IHH, mimicking OSA) on gut microbes in an animal model. We take advantage of a longitudinal study design and paired omics to investigate the microbial and molecular dynamics in the gut to ascertain the contribution of microbes on intestinal metabolism in IHH. We observe microbe-dependent changes in the gut metabolome that will guide future research on unrecognized mechanistic links between gut microbes and comorbidities of OSA. Additionally, we highlight novel and noninvasive biomarkers for OSA-linked cardiovascular and metabolic disorders.

Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies

OBJECTIVE

To systematically review associations between intake of saturated fat and trans unsaturated fat and all cause mortality, cardiovascular disease (CVD) and associated mortality, coronary heart disease (CHD) and associated mortality, ischemic stroke, and type 2 diabetes.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline, Embase, Cochrane Central Registry of Controlled Trials, Evidence-Based Medicine Reviews, and CINAHL from inception to 1 May 2015, supplemented by bibliographies of retrieved articles and previous reviews.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Observational studies reporting associations of saturated fat and/or trans unsaturated fat (total, industrially manufactured, or from ruminant animals) with all cause mortality, CHD/CVD mortality, total CHD, ischemic stroke, or type 2 diabetes.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted data and assessed study risks of bias. Multivariable relative risks were pooled. Heterogeneity was assessed and quantified. Potential publication bias was assessed and subgroup analyses were undertaken. The GRADE approach was used to evaluate quality of evidence and certainty of conclusions.

RESULTS

For saturated fat, three to 12 prospective cohort studies for each association were pooled (five to 17 comparisons with 90,501-339,090 participants). Saturated fat intake was not associated with all cause mortality (relative risk 0.99, 95% confidence interval 0.91 to 1.09), CVD mortality (0.97, 0.84 to 1.12), total CHD (1.06, 0.95 to 1.17), ischemic stroke (1.02, 0.90 to 1.15), or type 2 diabetes (0.95, 0.88 to 1.03). There was no convincing lack of association between saturated fat and CHD mortality (1.15, 0.97 to 1.36; P=0.10). For trans fats, one to six prospective cohort studies for each association were pooled (two to seven comparisons with 12,942-230,135 participants). Total trans fat intake was associated with all cause mortality (1.34, 1.16 to 1.56), CHD mortality (1.28, 1.09 to 1.50), and total CHD (1.21, 1.10 to 1.33) but not ischemic stroke (1.07, 0.88 to 1.28) or type 2 diabetes (1.10, 0.95 to 1.27). Industrial, but not ruminant, trans fats were associated with CHD mortality (1.18 (1.04 to 1.33) v 1.01 (0.71 to 1.43)) and CHD (1.42 (1.05 to 1.92) v 0.93 (0.73 to 1.18)). Ruminant trans-palmitoleic acid was inversely associated with type 2 diabetes (0.58, 0.46 to 0.74). The certainty of associations between saturated fat and all outcomes was "very low." The certainty of associations of trans fat with CHD outcomes was "moderate" and "very low" to "low" for other associations.

CONCLUSIONS

Saturated fats are not associated with all cause mortality, CVD, CHD, ischemic stroke, or type 2 diabetes, but the evidence is heterogeneous with methodological limitations. Trans fats are associated with all cause mortality, total CHD, and CHD mortality, probably because of higher levels of intake of industrial trans fats than ruminant trans fats. Dietary guidelines must carefully consider the health effects of recommendations for alternative macronutrients to replace trans fats and saturated fats.

Effects of elaidic acid on lipid metabolism in HepG2 cells, investigated by an integrated approach of lipidomics, transcriptomics and proteomics

Trans fatty acid consumption in the human diet can cause adverse health effects, such as cardiovascular disease, which is associated with higher total cholesterol, a higher low density lipoprotein-cholesterol level and a decreased high density lipoprotein-cholesterol level. The aim of the study was to elucidate the hepatic response to the most abundant trans fatty acid in the human diet, elaidic acid, to help explain clinical findings on the relationship between trans fatty acids and cardiovascular disease. The human HepG2 cell line was used as a model to investigate the hepatic response to elaidic acid in a combined proteomic, transcriptomic and lipidomic approach. We found many of the proteins responsible for cholesterol synthesis up-regulated together with several proteins involved in the esterification and hepatic import/export of cholesterol. Furthermore, a profound remodeling of the cellular membrane occurred at the phospholipid level. Our findings contribute to the explanation on how trans fatty acids from the diet can cause modifications in plasma cholesterol levels by inducing abundance changes in several hepatic proteins and the hepatic membrane composition.

Intake of trans fat and all-cause mortality in the Reasons for Geographical and Racial Differences in Stroke (REGARDS) cohort

BACKGROUND

A high intake of trans fatty acids decreases HDL cholesterol and is associated with increased LDL cholesterol, inflammation, diabetes, cancer, and mortality from cardiovascular disease. The relation between trans fat intake and all-cause mortality has not been established.

OBJECTIVE

The aim of this study was to determine the relation between trans fat intake and all-cause mortality.

DESIGN

We used data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study-a prospective cohort study of white and black men and women residing in the continental United States. Energy-adjusted trans fat intake was categorized into quintiles, and Cox-regression was used to evaluate the association between trans fat intake and all-cause mortality.

RESULTS

During 7 y of follow-up, there were 1572 deaths in 18,513 participants included in REGARDS. From the first to the fifth quintile of trans fat intake, the mortality rates per 1000 person-years of follow-up (95% CIs) were 12.8 (11.3, 14.5), 14.3 (12.7, 16.2), 14.6 (13.0, 16.5), 19.0 (17.1, 21.1), and 23.6 (21.5, 25.9), respectively. After adjustment for demographic factors, education, and risk factors for mortality, the HRs (95% CIs) for all-cause mortality were 1.00, 1.03 (0.86, 1.23), 0.98 (0.82, 1.17), 1.25 (1.05, 1.48), and 1.24 (1.05, 1.48), respectively (P-trend = 0.004). The population attributable risk due to trans fat intake was 7% (95% CI: 5%, 8%).

CONCLUSION

Higher trans fat intake is associated with an increased risk of all-cause mortality.

Erythrocyte membranetrans-fatty acid index is positively associated with a 10-year CHD risk probability

Industry-generatedtrans-fatty acids (TFA) are detrimental to risk of CHD, but ruminant-originated TFA have been reported as neutral or equivocal. Therefore, the total TFA amount should not be the only factor considered when measuring the effects of TFA. In the present study, we addressed whether a version of the TFA index that unifies the effects of different TFA isomers into one equation could be used to reflect CHD risk probability (RP). The present cross-sectional study involved 2713 individuals divided into four groups that represented different pathological severities and potential risks of CHD: acute coronary syndrome (ACS,n581); chronic coronary artery disease (CCAD,n631); high-risk population (HRP,n659); healthy volunteers (HV,n842). A 10-year CHD RP was calculated. Meanwhile, the equation of the TFA index was derived using five TFA isomers (trans-16 : 1n-7,trans-16 : 1n-9,trans-18 : 1n-7,trans-18 : 1n-9 andtrans-18 : 2n-6n-9), which were detected in the whole blood, serum and erythrocyte membranes of each subject. The TFA index and the 10-year CHD RP were compared by linear models. It was shown that only in the erythrocyte membrane, the TFA isomers were significantly different between the groups. In the ACS group, industry-generated TFA (trans-16 : 1n-9,trans-18 : 1n-9 andtrans-18 : 2n-6n-9) were the highest, whereas ruminant-originated TFA (trans-16 : 1n-7 andtrans-18 : 1n-7), which manifested an inverse relationship with CHD, were the lowest, and vice versa in the HV group. The TFA index decreased progressively from 7·12 to 5·06, 3·11 and 1·92 in the ACS, CCAD, HRP and HV groups, respectively. The erythrocyte membrane TFA index was positively associated with the 10-year CHD RP (R20·9981) and manifested a strong linear correlation, which might reflect the true pathological severity of CHD.

Adding MUFA to a dietary portfolio of cholesterol-lowering foods reduces apoAI fractional catabolic rate in subjects with dyslipidaemia

The present randomised parallel study assessed the impact of adding MUFA to a dietary portfolio of cholesterol-lowering foods on the intravascular kinetics of apoAI- and apoB-containing lipoproteins in subjects with dyslipidaemia. A sample of sixteen men and postmenopausal women consumed a run-in stabilisation diet for 4 weeks. Subjects were then randomly assigned to an experimental dietary portfolio either high or low in MUFA for another 4 weeks. MUFA substituted 13·0 % of total energy from carbohydrate (CHO) in the high-MUFA dietary portfolio. Lipoprotein kinetics were assessed after the run-in and portfolio diets using a primed, constant infusion of [2H3]leucine and multicompartmental modelling. The high-MUFA dietary portfolio resulted in higher apoAI pool size (PS) compared with the low-MUFA dietary portfolio (15·9 % between-diet difference, P= 0·03). This difference appeared to be mainly attributable to a reduction in apoAI fractional catabolic rate (FCR) after the high-MUFA diet ( − 5·6 %, P= 0·02 v. pre-diet values), with no significant change in production rate. The high-MUFA dietary portfolio tended to reduce LDL apoB100 PS compared with the low-MUFA dietary portfolio ( − 28·5 % between-diet difference, P= 0·09), predominantly through an increase in LDL apoB100 FCR (23·2 % between-diet difference, P= 0·04). These data suggest that adding MUFA to a dietary portfolio of cholesterol-lowering foods provides the added advantage of raising HDL primarily through a reduction in HDL clearance rate. Replacing CHO with MUFA in a dietary portfolio may also lead to reductions in LDL apoB100 concentrations primarily by increasing LDL clearance rate, thus potentiating further the well-known cholesterol-lowering effect of this diet.

Trans-fatty acids, dangerous bonds for health? A background review paper of their use, consumption, health implications and regulation in France

INTRODUCTION

Trans-fatty acids (TFAs) can be produced either from bio-hydrogenation in the rumen of ruminants or by industrial hydrogenation. While most of TFAs' effects from ruminants are poorly established, there is increasing evidence that high content of industrial TFAs may cause deleterious effects on human health and life span.

MATERIAL AND METHODS

Indeed, several epidemiological and experimental studies strongly suggest that high content of most TFA isomers could represent a higher risk of developing cardiovascular diseases by a mechanism that lowers the "good HDL cholesterol" and raises the "bad LDL cholesterol."

RESULTS

With respect to the general precautionary principle and considering the existence of an international policy consensus regarding the need for public health action, some industrialized countries, such as France, are still not sufficiently involved in preventive strategies that aim to efficiently reduce TFAs content and TFAs consumption and produce alternative healthier fat sources.

CONCLUSION

In this manuscript, we provide an overview about TFAs origins, their use and consumption among French population. We also discuss their potential human health implications as well as the preventive and regulatory measures undertaken in France.

Analysis of trans fatty acids production and squalene variation during amaranth oil extraction

The purpose of this study was to evaluate the decay of squalene and the formation of trans fatty acids (TFAs) in the amaranth oil extracted with hexane with and without heat. Oils were analyzed by determining their chemical values, and the fatty acids were identified and quantified by using Fourier-transform infrared (FTIR) spectroscopy, in the mid-region of 400–4000 cm−1, and gas chromatography. The FTIR analysis shows that two oil extracts (with and without heat) present a well-defined peak at 968 cm−1, which represents the trans double bonds. The quantified TFAs are

The relation between erythrocyte trans fat and triglyceride, VLDL- and HDL-cholesterol concentrations depends on polyunsaturated fat

Background

Trans fatty acids (TFA) lower HDL and increase triglyceride concentrations while polyunsaturated fatty acids (PUFA) lower triglycerides and may decrease HDL concentrations. The effect of the interaction between trans fat and PUFA on lipids is uncertain.

Methods

Men and women (n = 1032) in the Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN) study were included. Fatty acids in erythrocyte membranes were measured with gas chromatography while data on potential confounders were obtained from questionnaires. To test the interaction between total erythrocyte PUFA (ePUFA) and TFA (eTFA) on lipid concentrations we distributed eTFA into tertiles and dichotomized ePUFA at the median concentration.

Results

For the 1^st, 2^nd and 3^rd tertiles of eTFA, multivariate-adjusted means±s.e.m for HDL were 46.2±1.1, 46.3±1.1 and 45.5±1.0 mg/dL among those with low ePUFA, respectively, while they were 50.0±1.1, 46.9±1.1 and 44.7±1.1 mg/dL among those with high ePUFA, respectively (P for interaction = 0.01). For the 1^st, 2^nd and 3^rd tertiles of eTFA, multivariate-adjusted means±s.e.m for triglycerides were 178.6±11.3, 144.7±10.9 and 140.8±10.6, respectively, among those with low ePUFA, while they were 133.8±11.3, 145.7±10.9 and 149.3±11.5, respectively, among those with high ePUFA (P for interaction = 0.005). Results for VLDL were similar to those for triglycerides. No significant interactions were observed for LDL or total cholesterol.

Conclusions

The relation between trans fat and HDL, VLDL and triglycerides may depend on PUFA. The benefit of avoiding trans fat may be greater among individuals with higher PUFA intake. Supplementation with PUFA among individuals with relatively high trans fat intake may have limited benefits on lipid profiles.

Effect of short-term low- and high-fat diets on low-density lipoprotein particle size in normolipidemic subjects

High-fat, low-carbohydrate diets have been shown to raise plasma cholesterol levels, an effect associated with the formation of large low-density lipoprotein (LDL) particles. However, the impact of dietary intervention on time-course changes in LDL particle size has not been investigated. To test whether a short-term dietary intervention affects LDL particle size, we conducted a randomized, double-blind, crossover study using an intensive dietary modification in 12 nonobese healthy men with normal plasma lipid profile. Participants were subjected to 2 isocaloric 3-day diets: high-fat diet (37% energy from fat and 50% from carbohydrates) and low-fat diet (25% energy from fat and 62% from carbohydrates). Plasma lipid levels and LDL particle size were assessed on fasting blood samples after 3 days of feeding on each diet. The LDL particles were characterized by polyacrylamide gradient gel electrophoresis. Compared with the low-fat diet, plasma cholesterol, LDL cholesterol, and high-density lipoprotein cholesterol were significantly increased (4.45 vs 4.78 mmol/L, P = .04; 2.48 vs 2.90 mmol/L, P = .005; and 1.29 vs 1.41 mmol/L, P = .005, respectively) following the 3-day high-fat diet. Plasma triglycerides and fasting apolipoprotein B-48 levels were significantly decreased after the high-fat diet compared with the low-fat diet (1.48 vs 1.01 mmol/L, P = .0003 and 9.6 vs 5.5 mg/L, P = .008, respectively). The high-fat diet was also associated with a significant increase in LDL particle size (255.0 vs 255.9 Å;P = .01) and a significant decrease in the proportion of small LDL particle (<255.0 Å) (50.7% vs 44.6%, P = .01). As compared with a low-fat diet, the cholesterol-raising effect of a high-fat diet is associated with the formation of large LDL particles after only 3 days of feeding.

Lipid markers of "geometrical" radical stress: synthesis of monotrans cholesteryl ester isomers and detection in human plasma

Heteroatom-centered free radicals are able to transform cis unsaturated fatty acids to the thermodynamically more stable, but unnatural, trans configuration. The "geometrical" radical stress can be estimated in biological samples using trans fatty acid isomers as lipid markers. Regioselectivity is an important feature of the "geometrical" radical stress, because the supramolecular organization of the polyunsaturated fatty acid moieties of phospholipids can lead to preferential monotrans isomer formation. The regioisomer recognition is a crucial step, which is helped by appropriate molecular libraries available through radical-based synthetic methodologies. Cholesteryl linoleate and arachidonate esters are interesting targets for their biochemical connection with membrane phospholipid turnover and their well-known roles in cardiovascular health. The synthesis of monotrans isomers of PUFA cholesteryl esters was achieved by a thiyl radical-catalyzed cis-trans isomerization. Valuable NMR, IR, and Raman spectroscopic data have been collected for promising application in metabolomics and lipidomics. The identification of monotrans cholesteryl ester isomers was carried out in human plasma by GC, Raman, and IR analyses, demonstrating for the first time the presence of specific regiosiomers connected to free radical stress. This work helps to highlight the chemical biology approach for the access to molecular libraries applicable to biomarker development, and the cis-trans isomerization as a relevant process to be integrated in the puzzling scenario of free radical-mediated lipid modifications.

Trans fatty acids: effects on metabolic syndrome, heart disease and diabetes

The major dietary sources of trans fatty acids (TFAs) in most countries are partially hydrogenated vegetable oils. TFA consumption is a modifiable dietary risk factor for metabolic syndrome, diabetes mellitus, and coronary heart disease. Here, we review the available data on various effects of TFAs, including metabolic and signaling pathways that mediate these effects, affected tissues, and relationships with clinical end points. TFA consumption causes metabolic dysfunction: it adversely affects circulating lipid levels, triggers systemic inflammation, induces endothelial dysfunction, and, according to some studies, increases visceral adiposity, body weight, and insulin resistance. Dietary TFAs influence the function of multiple cell types, including hepatocytes, adipocytes, macrophages and endothelial cells. Among dietary fats and nutrients, TFAs seem to have a unique cardiometabolic imprint that is linked to insulin-resistance and metabolic-syndrome pathways. Consistent with these adverse physiological effects, consumption of even small amounts of TFAs (2% of total energy intake) is consistently associated with a markedly increased incidence of coronary heart disease. Relationships between TFA consumption and diabetes mellitus have been less consistent, possibly owing to differences in study designs. Nevertheless, the documented adverse effects of TFAs underscore their potential to cause harm and the importance of policy measures to minimize consumption of industrially produced TFAs.

Substitution of vegetable oil for a partially-hydrogenated fat favorably alters cardiovascular disease risk factors in moderately hypercholesterolemic postmenopausal women

OBJECTIVE

Compared to vegetable oils in their unmodified state, partially-hydrogenated fat is associated with less favorable effects on cardiovascular disease (CVD) risk factors. Acceptable alternatives must be adjudicated. Our objective was to assess the effect of a recent commercial fat substitution, corn oil for partially-hydrogenated soybean oil.

METHODS

Using a double-blind cross-over design, 30 postmenopausal women >or=50 years with LDL-cholesterol concentrations >or=120 mg/dL were randomly assigned to each of two 35-day phases; all food and beverage was provided to maintain body weight. Corn or partially-hydrogenated soybean oil was incorporated throughout the diet and contributed two-thirds of fat. Primary outcomes included fasting and non-fasting lipid, lipoprotein, apolipoprotein, and fasting high sensitivity C-reactive protein (hsCRP) concentrations; secondary outcomes included fasting small dense LDL (sdLDL)-cholesterol, remnant lipoprotein cholesterol (RemLC), glycated albumin, adiponectin and immunoreactive insulin concentrations, and endogenous cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyl transferase (LCAT) activities.

RESULTS

Relative to the partially-hydrogenated soybean oil enriched diet, the corn oil enriched diet resulted in lower fasting total cholesterol (7%; P<0.0001), LDL-cholesterol (10%; P<0.0001), VLDL-cholesterol (7%; P=0.052), apo B (9%; P<0.0001), lipoprotein (a) [Lp(a)] (5%; P=0.024), sdLDL-cholesterol (17%; P=0.001), and RemLC (20%; P=0.007) concentrations, and no significant effect on the other outcomes. Changes in postprandial (4-h post-meal) lipid, lipoprotein and apolipoprotein concentrations were similar to the fasting state.

CONCLUSION

The replacement of partially-hydrogenated soybean oil with corn oil favorably affects a range of CVD risk factors and is an appropriate option to decrease cardiovascular disease risk factors in moderately hypercholesterolemic individuals.

Effects of pistachios on cardiovascular disease risk factors and potential mechanisms of action: a dose-response study

BACKGROUND

Nut consumption lowers cardiovascular disease (CVD) risk. Studies are lacking about the effects of pistachios, a nutrient-dense nut, on CVD risk factors, dose-response relations, and lipid-lowering mechanisms.

OBJECTIVE

We evaluated the effects of 2 doses of pistachios, added to a lower-fat diet, on lipids and lipoproteins, apolipoprotein (apo)-defined lipoprotein subclasses, and plasma fatty acids. To investigate the mechanisms of action, we measured cholesteryl ester transfer protein and indexes of plasma stearoyl-CoA desaturase activity (SCD).

DESIGN

In a randomized crossover controlled-feeding study, 28 individuals with LDL cholesterol > or = 2.86 mmol/L consumed 3 isoenergetic diets for 4 wk each. Baseline measures were assessed after 2 wk of a typical Western diet. The experimental diets included a lower-fat control diet with no pistachios [25% total fat; 8% saturated fatty acids (SFAs), 9% monounsaturated fatty acids (MUFAs), and 5% polyunsaturated fatty acids (PUFAs)], 1 serving/d of a pistachio diet (1 PD; 10% of energy from pistachios; 30% total fat; 8% SFAs, 12% MUFAs, and 6% PUFAs), and 2 servings/d of a pistachio diet (2 PD; 20% of energy from pistachios; 34% total fat; 8% SFAs, 15% MUFAs, and 8% PUFAs).

RESULTS

The 2 PD decreased (P < 0.05 compared with the control diet) total cholesterol (-8%), LDL cholesterol (-11.6%), non-HDL cholesterol (-11%), apo B (-4%), apo B/apo A-I (-4%), and plasma SCD activity (-1%). The 1 PD and 2 PD, respectively, elicited a dose-dependent lowering (P < 0.05) of total cholesterol/HDL cholesterol (-1% and -8%), LDL cholesterol/HDL cholesterol (-3% and -11%), and non-HDL cholesterol/HDL cholesterol (-2% and -10%).

CONCLUSIONS

Inclusion of pistachios in a healthy diet beneficially affects CVD risk factors in a dose-dependent manner, which may reflect effects on SCD.

Macrophage cholesterol efflux elicited by human total plasma and by HDL subfractions is not affected by different types of dietary fatty acids

BACKGROUND

Plasma HDL concentrations and composition, important predictors of coronary heart disease, are modified by fatty acids (FAs) in high-fat diets.

OBJECTIVE

Following the National Cholesterol Education Program Adult Treatment Panel III recommendation that 25%-30% of total calorie intake be in the form of fat, we compared the results of the intake of 30% of energy as fat in diets enriched with trans, polyunsaturated, or saturated FAs. These dietary effects on the composition and ability of HDL(2), HDL(3), and total plasma to efflux cholesterol from mouse peritoneal macrophages that previously were loaded with LDL-acetylated 14C-cholesteryl ester were evaluated by using ultracentrifugally isolated lipoproteins.

DESIGN

After a 2-wk run-in period, 30 healthy persons (9 M, 21 F), were randomly distributed among 3 groups (n = 10/group) and fed for 4 wk with either an 8.3% trans FA, a 14.6% polyunsaturated FA, or a 13.2% saturated FA diet. The 3 diets had similar proportions of monounsaturated FAs.

RESULTS

The percentage of radioactive cell cholesterol removal did not vary among these diets, possibly because of the small difference in the composition of the HDL fraction elicited by the different diets. However, the percentage was consistently higher for HDL(3) than for HDL(2).

CONCLUSION

Differences in the cell cholesterol efflux with these diets were not observed, probably because the changes in the HDL composition were quite modest as a result of the limitation of the fat intake to 30% of total calories and because of the rigorous control of the proportions of FAs in the experimental diets used in this investigation.

Effect of postprandial lipaemia and Taq 1B polymorphism of the cholesteryl ester transfer protein (CETP) gene on CETP mass, activity, associated lipoproteins and plasma lipids

A large number of studies in recent years have investigated the effects of hyperlipidaemias and diabetes on cholesteryl ester transfer protein (CETP) on neutral lipid transfer activity and plasma lipids. There has been an ongoing debate as to whether CETP is pro- or anti-atherogenic as it provides a mechanism for the transfer of cholesterol from the cardioprotective HDL subfraction to the potentially atherogenic LDL subfraction. This study was designed to investigate whether there was significant variability of CETP mass and activity in a large normolipidaemic population and whether there is an association between CETP and plasma lipoprotein composition. The presence of a known polymorphism of CETP gene (Taq 1B) was investigated to see if there was any association between this polymorphism and CETP mass and activity, and plasma lipids. There was significant (P < 0·0001) increase in CETP mass and activity in plasma postprandially at 6 h. Using multiple stepwise regression analysis there was significant association with fasting CETP mass and activity (β = 0·055; P = 0·002) and triacylglycerol-rich lipoprotein (β = 0·013; P = 0·005) and postprandial CETP mass (β = 0·254; P = 0·007). Repeated-measures analysis showed a strong association between the absence of Taq 1B polymorphism and low CETP mass and elevated HDL- and HDL2-cholesterol and HDL-phospholipid concentrations than did those who were homozygous or heterozygous for the presence of the restriction site.

Diet and low-density lipoprotein particle size

Small, dense low-density lipoprotein (LDL) particles are being increasingly recognized as an important risk factor for cardiovascular disease. This paper provides an overview of how different diets and macronutrients modulate the LDL size phenotype. Data reviewed indicated that several components of the LDL size phenotype should be measured concurrently in order to fully appreciate the impact of diet on this complex trait. Data also suggested that numerous dietary elements have a significant impact on several characteristics of the LDL size phenotype, thus providing further evidence to the concept that specific dietary modifications can beneficially alter cardiovascular disease risk beyond their known and demonstrated effects on plasma LDL cholesterol concentrations.

Dietary Hydrogenated Fat Increases High-Density Lipoprotein apoA-I Catabolism and Decreases Low-Density Lipoprotein apoB-100 Catabolism in Hypercholesterolemic Women

OBJECTIVE

To determine mechanisms contributing to decreased high-density lipoprotein cholesterol (HDL-C) and increased low-density lipoprotein cholesterol (LDL-C) concentrations associated with hydrogenated fat intake, kinetic studies of apoA-I, apoB-100, and apoB-48 were conducted using stable isotopes.

METHODS AND RESULTS

Eight postmenopausal hypercholesterolemic women were provided in random order with 3 diets for 5-week periods. Two-thirds of the fat was soybean oil (unsaturated fat), stick margarine (hydrogenated fat), or butter (saturated fat). Total and LDL-C levels were highest after the saturated diet (P<0.05; saturated versus unsaturated) whereas HDL-C levels were lowest after the hydrogenated diet (P<0.05; hydrogenated versus saturated). Plasma apoA-I levels and pool size (PS) were lower, whereas apoA-I fractional catabolic rate (FCR) was higher after the hydrogenated relative to the saturated diet (P<0.05). LDL apoB-100 levels and PS were significantly higher, whereas LDL apoB-100 FCR was lower with the saturated and hydrogenated relative to the unsaturated diet. There was no significant difference among diets in apoA-I or B-100 production rates or apoB-48 kinetic parameters. HDL-C concentrations were negatively associated with apoA-I FCR (r=-0.56, P=0.03) and LDL-C concentrations were negatively correlated with LDL apoB-100 FCR (r=-0.48, P=0.05).

CONCLUSIONS

The mechanism for the adverse lipoprotein profile observed with hydrogenated fat intake is determined in part by increased apoA-I and decreased LDL apoB-100 catabolism.

A solid dietary fat containing fish oil redistributes lipoprotein subclasses without increasing oxidative stress in men

There is a demand and need for healthy solid dietary fats. However, synthetic fats can be tailored to contain specific physiologic properties. Our goal was to design dietary solid test fats that would be both beneficial to the atherogenic lipid profile and stable against lipid peroxidation. Sixteen men (age 35-75 y) substituted 80 g of their normal dietary fat intake with test fat for two periods of 21 d each in a double-blind, randomized, crossover study. Although solid, both test fats were low in cholesterol-raising SFA. Test fat "F" contained 5 g/100 g long chain (n-3) fatty acids matched by oleic acid in test fat "O." Plasma total triacylglycerol (TAG), VLDL TAG, cholesterol in VLDL, and intermediate density lipoproteins (IDL) were lower (P < 0.05), whereas apolipoprotein (apo) B of the large LDL-2 (d = 1031-1042 g/L) subclass, and cholesterol of HDL(2b) subclass, were higher after intake of F than O fat (P < 0.05). There was no difference in the effect on in vivo oxidation measured as the ratio of plasma isoprostanes F(2) to arachidonic acid and urinary isoprostanes, whereas the vitamin E activity/plasma total lipids ratio was higher after intake of F than O (P = 0.008). In conclusion, a solid dietary fat containing (n-3) PUFA decreased plasma TAG, VLDL, and IDL cholesterol, and redistributed lipoprotein subclasses in LDL and HDL, with a higher concentration of the larger and less atherogenic subfractions. These changes took place without an increase in oxidative stress as measured by in vivo markers.

Effects of medium-chain fatty acids and oleic acid on blood lipids, lipoproteins, glucose, insulin, and lipid transfer protein activities

BACKGROUND

Dietary medium-chain fatty acids (MCFAs) are of nutritional interest because they are more easily absorbed from dietary medium-chain triacylglycerols (MCTs) than are long-chain fatty acids from, for example, vegetable oils. It has generally been claimed that MCFAs do not increase plasma cholesterol, although this claim is poorly documented.

OBJECTIVE

We compared the effects of a diet rich in either MCFAs or oleic acid on fasting blood lipids, lipoproteins, glucose, insulin, and lipid transfer protein activities in healthy men.

DESIGN

In a study with a double-blind, randomized, crossover design, 17 healthy young men replaced part of their habitual dietary fat intake with 70 g MCTs (66% 8:0 and 34% 10:0) or high-oleic sunflower oil (89.4% 18:1). Each intervention period lasted 21 d, and the 2 periods were separated by a washout period of 2 wk. Blood samples were taken before and after the intervention periods.

RESULTS

Compared with the intake of high-oleic sunflower oil, MCT intake resulted in 11% higher plasma total cholesterol (P = 0.0005), 12% higher LDL cholesterol (P = 0.0001), 32% higher VLDL cholesterol (P = 0.080), a 12% higher ratio of LDL to HDL cholesterol (P = 0.002), 22% higher plasma total triacylglycerol (P = 0.0361), and higher plasma glucose (P = 0.033). Plasma HDL-cholesterol and insulin concentrations and activities of cholesterol ester transfer protein and phospholipid transfer protein did not differ significantly between the diets.

CONCLUSIONS

Compared with fat high in oleic acid, MCT fat unfavorably affected lipid profiles in healthy young men by increasing plasma LDL cholesterol and triacylglycerol. No changes in the activities of phospholipid transfer protein and cholesterol ester transfer protein were evident.

Dietary trans fatty acids and composition of human atheromatous plaques

Dietary fatty acids are incorporated into atheromatous plaques mainly in the form of cholesterol esters. Physicochemical properties of the plaque (e. g. mechanical strength) depend on its fatty acid composition. Trans isomers of unsaturated fatty acids (TFA) are known to reduce the availability of fatty acid precursors for the synthesis of anticoagulant PG(1) and PG(3) prostaglandins. The present study was undertaken to determine the content of trans isomers in atheromatous plaques and to search for correlations between trans isomers in the plaque and adipose tissue. Atheromatous plaques were obtained from 31 patients who underwent surgery due to atherosclerotic stenosis of the abdominal aorta, iliac or femoral arteries. Fatty acids were extracted and separated as methyl esters using gas chromatography (GC) with an internal standard. Correlations were searched for with statistical methods, taking the level of significance as p < 0.05. We found spatial and positional isomers of sixteen- and eighteen-carbon fatty acids in plaques and adipose tissue, with elaidic acid (C18:1 trans-9) being the most abundant. Every plaque and adipose tissue sample contained linolelaidic acid (C18:2 trans-9 trans-12) which is derived exclusively from linoleic acid, as well as conjugated dienes of linoleic acid (CLA) produced during oxidative processes. The presence of trans isomers of fatty acids in the atheromatous plaque seems to be of relevance to plaque formation. Of much concern is the detection of elaidic and linolelaidic acids which adversely affect the physiologically important metabolism of eicosanoids. The TFA pool in adipose tissue has little effect on the amount of these acids in the atheromatous plaque. Apparently, the presence of TFA in atheromatous plaques is the result of processes taking place during plaque formation and maturation.

Trans unsaturated fatty acids are less oxidizable than cis unsaturated fatty acids and protect endogenous lipids from oxidation in lipoproteins and lipid bilayers

Epidemiological data suggest that dietary trans unsaturated fatty acids increase the risk of heart disease; however, the underlying mechanisms are unclear. In this study, we investigated one possible mechanism, namely, their effect on LDL oxidation. Supplementation of LDL with 10% 16:1 trans-cholesteryl ester (CE) inhibited the oxidation compared to that with 16:1 cis-CE. Total replacement of core lipids with 18:2 trans,trans-CE decreased the rate of LDL oxidation by 19% compared to replacement with 18:2 cis,cis-CE. When the surface phosphoglycerides were replaced with either 16:0-18:2 cis,cis-phosphatidylcholine (PC) or 16:0-18:2 trans,trans-PC, the latter was found to inhibit the rate and increase the lag time of oxidation to a greater extent than the former. To confirm these findings, we studied the oxidation of PC liposomes by assessing the formation of conjugated dienes or the degradation of a fluorescently labeled PC. By both methods, the 16:0-18:2 trans,trans-PC exhibited greater resistance to oxidation than the 16:0-18:2 cis,cis-PC. Eliminating the fluidity differences did not completely eliminate the differences in oxidation rates, suggesting that the trans double bond is inherently resistant to oxidation. The composition of the conjugated hydroperoxy products formed after oxidation differed markedly for the two 18:2 isomers. Supplementation of 16:0-18:2 cis,cis-PC liposomes with 20 mol % di16:1 trans-PC retarded oxidation rates to a greater extent than supplementation with di16:1 cis-PC. These studies show that dietary trans unsaturated fatty acids decrease the rate of lipid peroxidation, an effect that may mitigate the atherogenic effect of these fatty acids.

Replacing 40% of dietary animal fat with vegetable oil is associated with lower HDL cholesterol and higher cholesterol ester transfer protein in cynomolgus monkeys fed sufficient linoleic acid

This study was designed to evaluate whether replacing approximately 40 g/100 g dietary animal fat with vegetable oil would improve plasma lipids and lipoproteins when diets contained prudent levels of total saturated acid (SFA), monounsaturated acid (MUFA) and PUFA. Using a cross-over design, male Cynomolgus monkeys (n = 10) were fed purified diets containing a mixture of fats. For the diet based on animal fat (AF-diet), approximately 85 g/100 g of the total fat was derived from pork fat, and approximately 40 g/100 g of this was replaced with olive oil for the vegetable oil-based diet (VO-diet). Thus, the fat content of the VO diet comprised 50% pork fat and 35% olive oil. The remaining 15% of the total fat (for both diets) was safflower oil. Both diets provided approximately 30% of total energy (%en) from fat, <10%en SFA and approximately 6-7%en from PUFA. Monkeys were rotated through two 7-wk feeding periods, during which time plasma lipids and lipoproteins were evaluated. Compared with the AF diet, plasma total cholesterol (TC) concentrations tended to be lower ( approximately 10%) after monkeys consumed the VO diet (3.18 +/- 0.83 vs. 3.52 +/- 0.93 mmol/L, P = 0.099), and this was due entirely to a significant 12% reduction in HDL cholesterol (1.53 +/- 0.41 vs. 1.73 +/- 0.47, mmol/L, P = 0.0009). Although plasma lipoprotein compositional analyses revealed no significant differences in either lipoprotein composition or the estimated particle diameters, the measurement of cholesterol ester transfer protein (CETP) using (3)H-cholesterol ester-labeled HDL revealed that the lower HDL cholesterol (HDL-C) when monkeys consumed the VO diet was associated with a 31% increase in transfer (P = 0.04). However, despite the changes in HDL-C, the TC/HDL-C ratio did not differ between monkeys after the two diet treatments. Regression analyses of data from these monkeys revealed a significant correlation between the dietary 16:0/18:2 ratio and plasma HDL-C. These data suggest that within the context of currently recommended prudent diets, it may be possible to manipulate HDL-C beneficially. Whether a similar effect would occur in humans warrants investigation.

Cholesterolaemic effect of palmitic acid in relation to other dietary fatty acids

The effect of dietary intake of high palmitic acid levels in combination with other fatty acids in normal subjects was assessed. Palmitic acid (10% of energy) was fed in conjunction with decreasing levels of linoleic acid to determine if a threshold level of linoleic acid prevented palmitic acid from being hypercholesterolaemic. Healthy subjects received each of the diet treatments for 21 days, followed by washout periods of 7 days. In a second experiment, the effect of exchanging palmitic acid for trans fatty acids on plasma lipoprotein cholesterol levels and on rates for endogenous synthesis of cholesterol in normal subjects was investigated. Diet treatment lasted for 30 days. On day 30 of each diet treatment, a priming dose of deuterium was consumed, followed by a subsequent blood sample at 24 h. Blood cholesterol fractions were isolated and analysed by isotope ratio mass spectrometry to measure cholesterol fractional synthetic rates. In the first experiment, total plasma cholesterol levels increased as the percentage of linoleic acid decreased. The data indicated that high levels of palmitic acid were not hypercholesterolaemic if intake of linoleic acid was greater than 4.5% of energy. When the diet contained trans fatty acids plasma total and low-density lipoprotein-cholesterol increased and cholesterol synthesis increased with a decrease in high-density lipoprotein-cholesterol.

High intakes of trans monounsaturated fatty acids taken for 2 weeks do not influence procoagulant and fibrinolytic risk markers for CHD in young healthy men

Dietary trans fatty acids are associated with increased risk of CHD. We hypothesized that the changes in plasma lipids associated with a high intake of trans fatty acids would cause adverse effects on procoagulant and fibrinolytic activities. A randomized crossover controlled feeding study was conducted in twenty-nine men. A trans-rich diet supplying 10 % energy as trans- 18:1 was compared with diets in which the trans fatty acids were replaced either with carbohydrate or oleate; each diet was taken for 2 weeks in random order. Fasting fibrinogen and d-dimer concentrations and factor VII coagulant, plasminogen activator inhibitor type 1 and tissue plasminogen activator did not differ between diets. Postprandially, tissue plasminogen activator activity increased and plasminogen activator inhibitor type 1 activity decreased on all diets. Factor VIIc increased postprandially by 15 and 17 % on the trans and oleate diets respectively, compared with an 11 % increase on the carbohydrate diet; the mean difference between oleate and carbohydrate diets was 6 (95 % CI 0.2, 11.9) %. The LDL-cholesterol:HDL-cholesterol and apolipoprotein B : apolipoprotein A-I ratios increased by 13 (95 % CI 5.7, 21.8) and 10 (95 % CI 3.1, 17.2) % respectively on the trans diet compared with the oleate diet and by 6 (95 % CI 0.1,12.7) and 7 (95 % CI 0, 13.5) % respectively compared with the carbohydrate diet. Plasma HDL2-cholesterol concentration was 18 (95 % CI 0.7, 35.9) % lower on the trans diet compared with the oleate diet. The results confirm adverse effects of trans fatty acids on HDL-cholesterol concentrations, but suggest that trans fatty acids do not have any specific effects on known haemostatic risk markers for cardiovascular disease in healthy young men in the short-term.

Plasma lipid modifications in elderly people after administration of two virgin olive oils of the same variety (Olea europaea var. hojiblanca) with different triacylglycerol composition

In the present study we examined whether two virgin olive oils (VOO1 and VOO2), of the same variety (Olea europaea var. hojiblanca with a similar composition of minor components but differing in the content of triacylglycerol molecular species, had different effects on blood pressure and plasma lipid levels in a healthy elderly population. Thirty-one participants, aged 84-9 (SD 6.4) years, were asked to participate in the study. No differences were found with regard to blood pressure after both experimental periods (VOO1 and VOO2). However, plasma total cholesterol and LDL-cholesterol were reduced only after VOO1 (P<0.01). The reduction of plasma cholesterol concentrations was related to the incorporation of oleic acid into plasma cholesteryl esters and phospholipids strongly correlated with plasma total cholesterol and LDL-cholesterol levels in all experimental periods studied (r2>0.418, P<0.07), except for phospholipids in VOO1 (P=0.130 for total cholesterol and p=0.360 for LDL-cholesterol). These results have demonstrated that blood pressure and plasma lipids can be modified by the consumption of VOO in elderly people, but that the extent of such modification depends on the composition and amount of active minor components and triacylglycerol molecular species.

Postprandial effects of dietary trans fatty acids on apolipoprotein(a) and cholesteryl ester transfer

BACKGROUND

The consumption of trans fatty acids adversely affects fasting plasma lipoprotein concentrations.

OBJECTIVE

This study aimed to investigate whether postprandial lipoprotein metabolism is affected by the consumption of trans fatty acids.

DESIGN

In a randomized crossover study, 19 healthy men consumed fatty meals that were identical except that 10% of energy was provided as trans 18:1 acids in the trans meal and as oleic acid in the cis meal.

RESULTS

The meals induced similar responses in plasma lipids. Cholesteryl ester transfer (CET) was activated after consumption of both meals (P < 0.0001); however, it was 28% higher after the trans meal than after the cis meal (280 +/- 129 compared with 219 +/- 116 nmol cholesteryl ester/mL plasma * 6 h; time x diet interaction: P < 0.0001). Plasma apolipoprotein(a) [apo(a)] concentrations remained constant; however, triacylglycerol-rich lipoproteins formed 4 h after ingestion of the trans meal contained a higher concentration of apo(a) than did those formed after ingestion of the cis meal (48.9 +/- 6.6 compared with 39.6 +/- 5.4 U/L; P < 0.02). The change in CET and in the proportion of plasma apo(a) in the triacylglycerol-rich lipoprotein fractions correlated with indexes of alimentary lipemia.

CONCLUSIONS

Consumption of meals high in trans fatty acids results in higher CET and postprandial lipoprotein concentrations enriched in apo(a) than does consumption of meals free of trans fatty acids. This study highlights the importance of double-bond configuration in determining postprandial lipoprotein composition.

The effect of dietary supplementation using isomeric blends of conjugated linoleic acid on lipid metabolism in healthy human subjects

Conjugated linoleic acid (CLA) refers to a group of positional and geometric isomers of linoleic acid. Studies using animal models have shown that CLA reduces adiposity, improves plasma lipoprotein metabolism and insulin sensitivity and reduces arteriosclerosis. Whilst CLA may have therapeutic potential with regard to coronary artery disease risk factors in human subjects, there has been little investigation into its effects in human subjects. This current study investigated the effects of dietary supplementation using two isomeric blends of CLA on triacylglycerol (TAG)-rich lipoprotein metabolism and reverse cholesterol transport in human subjects and evaluates whether CLA modulated cardiovascular disease risk factors. Fifty-one normolipidaemic subjects participated in this randomised double-blind placebo-controlled intervention trial. Subjects were randomly assigned to receive 3 g cis-9,trans-11-trans-10,cis-12 isomeric blend (50 : 50) or a cis-9,trans-11-trans-10,cis-12 isomeric blend (80 : 20) CLA or linoleic acid (control)/d for 8 weeks. The 50 : 50 CLA isomer blend significantly reduced (P<or=0.005) fasting plasma TAG concentrations. The 80 : 20 CLA isomer blend significantly reduced (P<or=0.05) VLDL-cholesterol concentrations. CLA supplementation had no significant effect on LDL-cholesterol, HDL-lipid-protein composition or reverse cholesterol transport. CLA supplementation had no effect on body weight, plasma glucose and insulin concentrations. Fatty acid analysis revealed that the cis-9,trans-11 CLA isomer was incorporated into total plasma lipids following supplementation with both isomeric blends of CLA. The present study demonstrates that CLA supplementation significantly improves plasma TAG and VLDL metabolism in human subjects. The study confirms that some of the cardio-protective effects of CLA that were shown in animal studies are relevant to man.

Trans fatty acids affect lipoprotein metabolism in rats

This study was designed to investigate the effects of oleic (CIS), palmitic (SAT) and trans fatty acids (TRANS) on cholesterol metabolism. Rats fed the TRANS diet had lower plasma total cholesterol (P < 0.005) and non-HDL-cholesterol (non HDL-C) concentrations (P < 0.005) compared with their CIS-fed counterparts. Plasma HDL-C was highest in rats fed the SAT diet (P = 0.01). An in vivo assay of reverse cholesterol transport (RCT) was performed whereby radiolabeled cholesterol was delivered to the liver as acetylated LDL and the reappearance of label into plasma and HDL was determined. Plasma radioactivity in TRANS-fed rats was lower than in their SAT-fed counterparts (P = 0.01), and consistent with the cholesterol distribution in plasma, the difference was due to lower [(3)H]-cholesterol in lower density lipoproteins. Despite diet-induced differences in the cholesterol and phospholipid concentrations and fatty acid composition of HDL, the amount of label in HDL did not differ among groups, suggesting that consumption of these diets resulted in HDL populations with similar capacity to participate in RCT. The present findings suggest that dietary trans fatty acids regulate the metabolism of apolipoprotein B-containing lipoproteins in rats and that the effect may be masked in species possessing high plasma cholesteryl ester transfer protein (CETP) activity. These results reinforce the important role of CETP activity in determining the distribution of plasma cholesterol in response to dietary trans fatty acids.

A biochemical analysis of people with chronic fatigue who have Irlen Syndrome: speculation concerning immune system dysfunction

This study investigated the biological basis of visual processing disabilities in adults with Chronic Fatigue Syndrome. The study involved 61 adults with symptoms of Chronic Fatigue Syndrome who were screened for visual processing problems (Irlen Syndrome) and divided into two groups according to the severity of symptoms of Irlen Syndrome. Significant variations were identified in blood lipids and urine amino and organic acids of the two groups, which may be indicative of activation of the immune system due to some infective agent. It was suggested that metabolic profiling may help the development of more valid diagnostic categories and allow more investigation of immune system dysfunction as a possible causal factor in a range of learning and behaviour disorders.

Effect of dietary elaidic versus vaccenic acid on blood and liver lipids in the hamster

Male hamsters (30 per group) were fed five different semi-purified diets ad libitum. The diets, containing 30% of energy (en%) as fat, differed in their dietary fat composition (specified fatty acids exchanged at 10 en%) and were fed for 4 weeks. The five fatty acids compared in mixed triglycerides were elaidic acid (C18:1 9t), vaccenic acid (C18:1 11t), their cis-counterpart oleic acid (C18:1 9c), medium-chain fatty acids (MCFA; C8:0 and C10:0), and palmitic acid (C16:0). Compared with oleic acid, dietary MCFA and palmitic acid tended to increase blood cholesterol levels in the hamsters. The effect of elaidic and vaccenic acid on blood cholesterol did not differ from that of oleic acid. When elaidic acid and vaccenic acids were compared directly, the ratio of LDL/HDL-cholesterol in plasma was significantly higher in hamsters fed vaccenic acid than in those fed elaidic acid, and elaidic acid was incorporated at low levels, but more efficiently than vaccenic acid at the sn-2 position of platelet phospholipids. Biological consequences of this low incorporation are considered unlikely as levels of arachidonic acid (C20:4 n-6) and docosohexaenoic acid (C22:6 n-3) in the platelet phospholipids of all dietary groups did not differ. With respect to the effect on the LDL/HDL-cholesterol ratio, elaidic acid may be preferable to vaccenic acid. We conclude that this animal study does not provide evidence for the suggestion, based on epidemiological observations, that elaidic acid would be more detrimental to cardiovascular risk than vaccenic acid.