Lipoproteins, nutrition, and heart disease

Genes, fat intake, and cardiovascular disease risk factors in the Quebec Family Study

OBJECTIVE

The aim of this study was to assess gene-diet interaction effects on cardiovascular disease (CVD) risk factors (waist circumference, plasma triacylglycerol, high-density lipoprotein-cholesterol and fasting glucose concentrations, and diastolic and systolic blood pressure) in the Quebec Family Study cohort.

DESIGN

Sixty-four polymorphisms from 45 candidate genes were studied in 645 subjects. Dietary fat intake was obtained from a 3-day weighted food record.

RESULTS

We observed 18 significant interactions at a p value <or= 0.01. Among them, the Pro12Ala polymorphism in peroxisome proliferator-activated receptor gamma, alone or in interaction with fat intake, significantly modulated waist circumference (p = 0.0005 for both effects). Additionally, the apolipoprotein E genotype in interaction with fat intake was significantly associated with diastolic and systolic blood pressure (p = 0.01 and p = 0.001, respectively). The ghrelin Leu72Met polymorphism also interacted with dietary fat in its relation to waist circumference and triacylglycerol concentrations (p = 0.0004 and p = 0.005).

DISCUSSION

These results suggest that several alleles at candidate genes interact with dietary fat intake to modulate well-known CVD risk factors. The identification of gene-diet interaction effects is likely to provide useful information concerning the etiology of CVD.

Rational approach to the treatment for heterozygous familial hypercholesterolemia in childhood and adolescence: a review

Atherosclerosis represents a disease that begins in childhood and in which LDL cholesterol plays a pivotal role for the development of the pathology. Children and adolescents with high cholesterol levels are more likely than their peers to present cholesterol elevation as adults. The identification of genetic dyslipidemias associated with premature cardiovascular disease is crucial during childhood to delay or prevent the atherosclerotic process. Guidelines for the diagnosis and treatment of hypercholesterolemia during pediatric age are available from the National Cholesterol Education Program. A heart-healthy diet should begin at the age of 2 yr and a large number of studies have demonstrated no adverse effects on nutritional status, growth, pubertal development, and psychological aspects in children and adolescents limiting total and saturated fat intake. Pharmacotherapy should be considered in children over 10 yr of age when LDL cholesterol concentrations remain very high despite severe dietary therapy, especially when multiple risk factors are present. The only lipid-lowering drugs recommended up to now for childhood and adolescence are resins reported to be effective and well tolerated, although compliance is very poor because of unpalatability. The use of statins is increasing and seems to be effective and safe in children, even if studies enrolled a small number of patients and evaluated efficacy and safety for short-term periods. Recently, an interesting drug represented by ezetimibe has been found that may provide cholesterol-lowering additive to that reached with statin treatment. This review provides an update on recent advances in the diagnosis, therapy, and follow-up of familial hypercholesterolemia during pediatric age and adolescence.

Docosahexaenoic acid supplementation improves fasting and postprandial lipid profiles in hypertriglyceridemic men

BACKGROUND

The effects of docosahexaenoic acid (DHA) on the mean size and concentrations of VLDL, LDL, and HDL subclasses have not been previously studied.

OBJECTIVE

We determined the effects of DHA supplementation on the concentrations of apoproteins; large, medium, and small VLDL, LDL, and HDL particles; and the mean diameters of these particles in fasting and postprandial plasma.

DESIGN

Hypertriglyceridemic men aged 39-66 y (n = 34) participated in a double-blind, randomized, placebo-controlled parallel study. They received no supplements for the first 8 d and received either 7.5 g DHA oil/d (3 g DHA/d) or olive oil (placebo) for the last 90 d. Lipoprotein particle diameters and concentrations were measured by nuclear magnetic resonance spectroscopy.

RESULTS

DHA supplementation for 45 d significantly (P < 0.05) decreased concentrations of fasting triacylglycerol (24%), large VLDL (92%), and intermediate-density lipoproteins (53%) and the mean diameter of VLDL particles (11.1 nm). It elevated concentrations of LDL cholesterol (12.6%), small VLDL particles (133%), and large LDL particles (120%) and the mean diameter of LDL particles (0.6 nm) in fasting plasma. Similar changes were observed for area under the curve for postprandial samples (0-6 h); however, the number of small dense LDL particles decreased significantly (21%), and the change in LDL cholesterol was not significant. Continued supplementation with DHA beyond 45 d caused no further changes; placebo treatment altered none of the responses tested.

CONCLUSION

DHA supplementation may improve cardiovascular health by lowering concentrations of triacylglycerols and small, dense LDL particles.

Dietary fat intake and relationship to serum lipid levels in HIV-infected patients with metabolic abnormalities in the HAART era

OBJECTIVE

To evaluate dietary intake and its relationship to lipid parameters in HIV-infected patients with metabolic abnormalities.

METHOD

We prospectively determined dietary intake (4-day food records or 24-h recall) in 356 HIV-infected patients and 162 community-derived HIV-negative controls evaluated for metabolic studies between 1998-2005. Differences in dietary intake between HIV-infected patients and non-HIV-infected controls, in relation to the established 2005 USDA (United States Department of Agriculture) Recommended Dietary Guidelines, were determined. The relationship between dietary fat intake and serum lipid levels among HIV-infected individuals was also evaluated.

RESULTS

Assessment of dietary intake in this group of HIV-infected patients demonstrated increased intake of total dietary fat (P < 0.05), saturated fat (P = 0.006), and cholesterol (P = 0.006) as well as a greater percentage of calories from saturated fat (P = 0.002) and from trans fat (P = 0.02), despite similar caloric intake to the control individuals. A significantly higher percentage of HIV-infected patients were above the 2005 USDA Recommended Dietary Guidelines for saturated fat (> 10%/day) (76.0% HIV vs. 60.9% controls, P = 0.003), and cholesterol (> 300 mg/day) (49.7% HIV vs. 37.9% controls, P = 0.04). Saturated fat intake was strongly associated with triglyceride level [triglyceride level increased 8.7 mg/dl (parameter estimate) per gram of increased saturated fat intake, P = 0.005] whereas total fat was inversely associated with triglyceride level [triglyceride level decreased 3.0 mg/dl (parameter estimate) per gram of increased total fat intake, P = 0.02] among HIV-infected individuals.

CONCLUSIONS

Increased intake of saturated fat is seen and contributes to hypertriglyceridemia among HIV-infected patients who have developed metabolic abnormalities. Increased saturated fat intake should be targeted for dietary modification in this population.

Hiperlipidemias e fatores dietéticos: estudo transversal entre nipo-brasileiros

Este estudo teve como objetivo avaliar a associação entre hiperlipidemia e dieta de nipo-brasileiros de Bauru, município do Estado de São Paulo. Foram obtidos de 1.330 indivíduos dados mediante questionários previamente testados (dados demográficos e dietéticos). Os exames físicos e laboratoriais incluíram a coleta (ou dosagem) antropométrica, de pressão arterial, de glicemia de jejum e de 2 horas, de perfil lipídico e de TSH e T4 livre. Utilizaram-se teste qui-quadrado e medida de odds ratio para avaliar associação entre as variáveis estudadas e presença de hiperlipidemia. Foi encontrado 81,5% de hiperlipidêmicos e acometeu, principalmente, indivíduos tabagistas, com excesso de peso, hipotireoidismo, hipertensão arterial e intolerância a glicose. Observaram-se, mediante análise bruta, relações entre hiperlipidemia e ácido graxo saturado, ácido oléico e fibras de grãos e cereais. Após o ajuste para as variáveis de controle, observaram-se associações entre hiperlipidemia e consumo de lípides (totais, ácido oléico, saturados e trans), fibras e álcool. Conclui-se que mudanças no estilo de vida, particularmente no hábito alimentar, podem levar a uma melhora do quadro hiperlipidêmico e que o consumo de lípides pode ser um dos principais fatores para o aumento da hiperlipidemia. Estudos prospectivos auxiliarão para testar essas hipóteses nos nipo-brasileiros de Bauru.

The biology and chemistry of hyperlipidemia

Coronary arterial diseases are responsible for more deaths than all other associated causes combined. Elevated serum cholesterol levels leading to atherosclerosis can cause coronary heart disease (CHD). Reduction in serum cholesterol levels reduces the risk for CHD, substantially. Medicinal chemists all around the world have been designing, synthesizing, and evaluating a variety of new bioactive molecules for lowering lipid levels. This review summarizes the disorders associated with elevation of lipids in blood and the current strategies to control them. The emphasis has been laid in particular on the new potential biological targets and the possible treatments as well as the current ongoing research status in the field of lipid lowering agents.

Divergent in vitro and in vivo lipid peroxidation in the postprandial phase of patients with type I diabetes mellitus

OBJECTIVE

The two- to fourfold higher risk of cardiovascular disease in diabetes mellitus is more strongly predicted by the postprandial than by the fasting blood glucose and lipids. We aimed to investigate the impact of postprandial changes in serum lipoprotein fractions on lipid peroxidation in type I diabetes mellitus (T1DM).

DESIGN

This was a prospective observational study.

SETTING

The study was performed at Antwerp University Hospital, Belgium.

SUBJECTS

Twenty-three well-controlled T1DM patients were included.

INTERVENTION

Patients received a standard breakfast and lunch (>50% energy as fat). Blood was sampled at fasting (F), after the post-breakfast hyperglycemic peak (BP), just before lunch (B), after the post-lunch hyperglycemic peak (LP), after the post-lunch dale (LD) and 5 h after lunch (L) for the measurement of serum lipids, lipoprotein subfraction composition, alpha-tocopherol and lipid peroxidation in vivo and in vitro.

RESULTS

Serum triacylglycerols (Tgs) increased (from 1.03+/-0.40 at F to 1.60+/-0.87 mmol/l at LP, P=0.001), but cholesterol decreased by 12% in parallel with alpha-tocopherol (from 4.43+/-0.76 at F to 4.12+/-0.82 micromol/mmol total lipid at B, P=0.006). Although plasma malondialdehyde increased from 1.02+/-0.36 at F to 1.14+/-0.40 micromol/L at LP, P=0.03, copper-induced in vitro peroxidation decreased in the low-density lipoprotein and high-density lipoprotein fractions.

CONCLUSIONS

In well-controlled T1DM patients moderate postprandial increases in serum Tgs are accompanied by a relative deficiency in alpha-tocopherol. Lipid peroxidation in vivo increases but cannot be ascribed to changes in the susceptibility of lipoproteins to copper-induced in vitro peroxidation.

Decreasing linoleic acid with constant alpha-linolenic acid in dietary fats increases (n-3) eicosapentaenoic acid in plasma phospholipids in healthy men

High linoleic acid (LA) intakes have been suggested to reduce alpha-linolenic acid [ALA, 18:3(n-3)] metabolism to eicosapentaenoic acid [EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)], and favor high arachidonic acid [ARA, 20:4(n-6)]. We used a randomized cross-over study with men (n = 22) to compare the effect of replacing vegetable oils high in LA with oils low in LA in foods, while maintaining constant ALA, for 4 wk each, on plasma (n-3) fatty acids. Nonvegetable sources of fat, except fish and seafoods, were unrestricted. We determined plasma phospholipid fatty acids at wk 0, 2, 4, 6, and 8, and triglycerides, cholesterol, serum CRP, and IL-6, and platelet aggregation at wk 0, 4, and 8. LA and ALA intakes were 3.8 +/- 0.12% and 1.0 +/- 0.05%, and 10.5 +/- 0.53% and 1.1 +/- 0.06% energy with LA:ALA ratios of 4:0 and 10:1 during the low and high LA diets, respectively. The plasma phospholipid LA was higher and EPA was lower during the high than during the low LA diet period (P < 0.001), but DHA declined over the 8-wk period (r = -0.425, P < 0.001). The plasma phospholipid ARA:EPA ratios were (mean +/- SEM) 20.7 +/- 1.52 and 12.9 +/- 1.01 after 4 wk consuming the high or low LA diets, respectively (P < 0.001); LA was inversely associated with EPA (r = -0.729, P < 0.001) but positively associated with ARA:EPA (r = 0.432, P < 0.001). LA intake did not influence ALA, ARA, DPA, DHA, or total, LDL or HDL cholesterol, CRP or IL-6, or platelet aggregation. In conclusion, high LA intakes decrease plasma phospholipid EPA and increase the ARA:EPA ratio, but do not favor higher ARA.

Estimated intake of milk fat is negatively associated with cardiovascular risk factors and does not increase the risk of a first acute myocardial infarction. A prospective case–control study

Milk fat is high in saturated fatty acids (SFA) and high intakes of SFA are associated with cardiovascular diseases. The aim of the present study was to prospectively evaluate the potential risk of a first-ever acute myocardial infarction (AMI) in relation to the estimated milk-fat intake, reflected as the proportions of pentadecanoic acid (15:0) and heptadecanoic acid (17:0) in serum lipid esters. This was evaluated in a study population selected within the Västerbotten Intervention Program and the northern Sweden ‘Monitoring of Trends and Determinants in Cardiovascular disease’ survey populations. A prospective case–control design was used. The proportions of the biomarkers were lower in the cases (n78) than in the controls (n156), who were matched for age, sex, sampling time and geographical region. The standardised odds ratios of becoming an AMI case were between 0·7 and 0·8 for the biomarkers. The proportions of 15:0 and 17:0 in serum phospholipids were significantly and negatively correlated to serum concentrations of plasminogen activator inhibitor-1, tissue-type plasminogen activator, triacylglycerols, insulin, specific insulin, pro-insulin and leptin (allP<0·0001), suggesting a negative relationship to the insulin-resistance syndrome and the risk of CHD. Adjustment for BMI did not materially change the relationships. Although there seems to be a negative association between milk-fat intake as mirrored by the proportions of 15:0 and 17:0 in serum lipid esters and a first-ever AMI, adjustment for clinical risk factors removed this relationship.

UK Food Standards Agencycis-monounsaturated fatty acid workshop report

The UK Food Standards Agency convened a group of expert scientists to review current research investigating the optimal dietary intake forn-9cis-monounsaturated fatty acids (MUFA). The aim was to review the mechanisms underlying the reported beneficial effects of MUFA on CHD risk, and to establish priorities for future research. The issue of optimal MUFA intake is contingent upon optimal total fat intake; however, there is no consensus of opinion on what the optimal total fat intake should be. Thus, it was recommended that a large multi-centre study should look at the effects on CHD risk of MUFA replacement of saturated fatty acids in relation to varying total fat intakes; this study should be of sufficient size to take account of genetic variation, sex, physical activity and stage of life factors, as well as being of sufficient duration to account for adaptation to diets. Recommendations for studies investigating the mechanistic effects of MUFA were also made. Methods of manipulating the food chain to increase MUFA at the expense of saturated fatty acids were also discussed.

Effect of tea catechins on postprandial plasma lipid responses in human subjects

Epidemiological surveys suggest that a higher intake of tea may be associated with a lower risk of CHD. There is accumulating evidence that postprandial lipaemia makes a substantial contribution to the incidence of CHD. Our aim was, therefore, to evaluate the effect of tea catechins (major ingredients in green tea) on postprandial lipid responses in human subjects after the consumption of test meals. In a randomized triple-crossover design, nine male subjects with mild or borderline hypertriacylglycerolaemia consumed 10 (control), 224 (moderate dose) and 674 mg (high dose) of the assigned tea catechins three times each along with a standardized light meal consisting of a piece of bread spread with 20 g butter. Plasma lipids were measured in the fasting state and 1, 2, 3, 4 and 6 h after consuming the light meal. Results showed that, compared with the control, moderate and high doses of tea catechins reduced the incremental area under the plasma triacylglycerol curves by 15·1 and 28·7 %, respectively. Next, the rapid elevation of remnant-like particle cholesterol was significantly inhibited by a high dose of tea catechins 2 h after consuming the light meal (P<0·01). In the range of tea catechin dosages, no significant differences were observed in the postprandial responses for plasma total cholesterol or NEFA at any time point. In conclusion, this trial demonstrated that tea catechins attenuated the postprandial increase in plasma triacylglycerol levels following a fat load. These results may provide evidence for one of the possible mechanisms involved in lowering the incidence of CVD, and may prove useful in further studies on the beneficial health effects of tea drinking.

Participants' willingness to consume soy foods for lowering cholesterol and receive counselling on cardiovascular disease by nutrition professionals

Objectives

To determine if participants would be interested in consuming soy foods to lower cholesterol in primary and secondary prevention of heart disease, and to identify the role physicians and registered dietitians have in providing dietary advice, about soy foods or other foods, for participants with elevated cholesterol.

Methodology

Qualitative data from 12 focus groups were gathered from a convenience sample of 74 adults, aged 18–91 years, with and without high cholesterol (total cholesterol >200 mg dl−1). Participants were recruited from Minneapolis/St. Paul mainstream and natural foods grocery stores. Focus group interviews were taped and transcribed verbatim. Common themes were identified, coded and compared using NVivo computer software.

Results

Participants believed diet, lifestyle and genetics were the cause of high cholesterol and cardiovascular disease (CVD). Few participants were aware of the Food and Drug Administration health claim for soy protein, yet many were willing to consume soy as part of lifestyle modification to prevent CVD. They reported preferring food and exercise over medication to treat high cholesterol. Few participants had ever received dietary advice from physicians on treating high cholesterol or CVD, and most doubted the accuracy of such advice. They believed registered dietitians were the most credible source of nutrition counselling and expressed an interest in physician referrals to dietitians.

Conclusions

A collaboration and referral system between physicians and registered dietitians could increase CVD patients' consumption of soy foods as a means potentially leading to a reduced risk of heart disease in participants.

Cost-benefit analysis of a plant sterol containing low-fat margarine for cholesterol reduction

For decreasing the risk of coronary heart disease (CHD) it has been proposed to enrich food such as margarine with plant sterol esters which have been shown to reduce total and LDL cholesterol concentrations, two of the major risk factors. A Markov model was developed to assess the costs and benefits of consuming a low-fat plant sterol containing margarine (PS margarine). A health insurer's perspective was taken with a time frame of 10 years. Transition probabilities for CHD and CHD-related death were calculated on the basis of the Framingham risk equations. These were applied to a representative sample of the German population. The alteration in cholesterol levels after intake of PS margarine was estimated based on a meta-analysis of ten randomized controlled trials with parallel or crossover design that found a reduction of 5.7% in total cholesterol. Average annual costs of CHD were assumed to be at 3,000 euro. Costs for "no CHD" and "CHD-related death" were set to 0 euro since the intervention would solely be paid by the consumers. Sensitivity analyses were performed with regard to annual costs, risk estimation, PS margarine reduction in total cholesterol, discount factor, and risk of CHD-related death. The 10-year CHD risks are 6.1% (PS margarine) vs. 6.5% (control). Thus expected 10-year CHD costs are 696 euro (PS margarine) vs. 748 euro (control). The cost savings of 52 euro varied between 32 euro and 74 euro in the sensitivity analysis. A projection at the level of the population for which evidence (randomized controlled trials) exists that plant sterols lower cholesterol (25.35 million) leads to a reduction of 117,000 CHD cases over 10 years and a cost reduction of 1.3 billion euro for this time period (sensitivity analysis 0.8-1.9 billion euro).

Nutrição e excesso de massa corporal: fatores de risco cardiovascular em adolescentes

OBJETIVO: Verificar a freqüência de hipertensão arterial, sedentarismo e consumo alimentar inadequado em adolescentes com excesso de massa corporal. MÉTODOS: Estudo transversal com 56 adolescentes, sendo 21 meninos e 35 meninas, entre 10 e 19 anos. As variáveis foram: sexo, idade, peso, estatura, índice de massa corporal, classificação nutricional, hipertensão arterial, atividade física e consumo alimentar de risco cardiovascular. Avaliou-se o consumo alimentar com questionário que estabelece consumo de risco cardiovascular entre adolescentes por categorias de consumo, segundo pontuações por quantidades e freqüência consumida. Do questionário originaram-se as variáveis categorias de consumo e pontuações. Aplicou-se correlação de Spearman entre índice de massa corporal, idade e pontuação de consumo. Por teste "t" de Student compararam-se entre os sexos as médias de índice de massa corporal, idade, massa corporal, estatura e pontuação de consumo, e por qui-quadrado as freqüências por presença e ausência de hipertensão arterial, prática de atividade física e categorias de consumo. Com teste Kruskal-Wallis, analisou-se a variância da pontuação de consumo entre grupos. RESULTADOS: Não houve diferenças estatísticas entre os sexos para atividade física (p=0,68), hipertensão arterial (p=0,94), excesso de massa corporal (p=0,31) e categorias de consumo (p=0,53). O índice de massa corporal não se correlacionou com a idade (r=0,20 e p=0,14) e a pontuação de consumo (r=-0,06 e p=0,60). Não houve diferença estatística (p=0,19) na pontuação do consumo por grupos. CONCLUSÃO: Os adolescentes não apresentaram distinções por sexo quanto à prevalência de hipertensão arterial, sedentarismo e consumo alimentar de risco cardiovascular, embora as meninas apresentassem maior freqüência desses fatores quando agrupados.

Ácidos graxos poliinsaturados ômega-3 e ômega-6: importância e ocorrência em alimentos

Os ácidos graxos poliinsaturados abrangem as famílias de ácidos graxos ômega-3 e ômega-6. Os ácidos graxos de cadeia muito longa, como os ácidos araquidônico e docosaexaenóico, desempenham importantes funções no desenvolvimento e funcionamento do cérebro e da retina. Esse grupo de ácidos graxos não pode ser obtido pela síntese de novo, mas pode ser sintetizado a partir dos ácidos linoléico e alfa-linolênico presentes na dieta. Neste artigo são considerados os principais fatores que podem inibir a atividade das enzimas dessaturases envolvidas na síntese dos ácidos graxos de cadeia muito longa. São apresentadas as recomendações da razão ômega-6/ômega-3 na dieta, propostas em diversos países, sendo verificada a convergência para o intervalo de 4 a 5:1. São relacionados alimentos que podem contribuir para aumentar a ingestão do ácido alfa-linolênico e dos ácidos graxos de cadeia muito longa. A essencialidade dos ácidos graxos de cadeia muito longa é muito dependente do metabolismo do indivíduo, sendo que a razão n-6/n-3 da dieta exerce grande influência nesse sentido.

Dietary trans fatty acids: Review of recent human studies and food industry responses

Dietary trans FA at sufficiently high levels have been found to increase low density lipoprotein (LDL)-cholesterol and decrease high density lipoprotein (HDL)-cholesterol (and thus to increase the ratio of LDL-cholesterol/HDL-cholesterol) compared with diets high in cis monounsaturated FA or PUFA. The dietary levels of trans FA at which these effects are easily measured are around 4% of energy or higher to increase LDL-cholesterol and around 5 to 6% of energy or higher to decrease HDL-cholesterol, compared with essentially trans-free control diets. Very limited data at lower levels of intake (less than 4% of energy) are available. Most health professional organizations and some governments now recommend reduced consumption of foods containing trans FA, and effective January 1, 2006, the U.S. Food and Drug Administration requires the labeling of the amounts of trans FA per serving in packaged foods. In response, the food industry is working on ways to eliminate or greatly reduce trans FA in food products. Current efforts focus on four technological options: (i) modification of the hydrogenation process, (ii) use of interesterification, (iii) use of fractions high in solids from natural oils, and (iv) use of trait-enhanced oils. Challenges to the food industry in replacing trans FA in foods are to develop formulation options that provide equivalent functionality, are economically feasible, and do not greatly increase saturated FA content.

Dietary polyunsaturated fat intake is associated with low-density lipoprotein size, but not with susceptibility to oxidation in subjects with impaired glucose metabolism and type II diabetes: the Hoorn study

OBJECTIVE

A high monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) intake is associated with lower plasma low-density lipoprotein (LDL)-cholesterol. However, PUFA may increase the susceptibility of LDL to undergo oxidative modifications. The aim of this study was to analyze the association of habitual dietary fat intake with LDL size and oxidizability.

DESIGN

Cross-sectional.

SETTING

Cohort study.

SUBJECTS

Seven hundred and fifty-eight subjects with normal, impaired glucose metabolism and type II diabetes.

INTERVENTIONS

Mean LDL size was measured by high-performance gel-filtration chromatography. In vitro oxidizability of LDL was determined by measuring lag time, reflecting the resistance of LDL to copper-induced oxidation. Information about dietary fat intake was obtained by a validated food frequency questionnaire.

RESULTS

PUFA intake (energy percent) was significantly and negatively associated with LDL size in subjects with type II diabetes (standardized beta (95% confidence interval) -0.17 (-0.28;-0.06)) and impaired glucose metabolism - although not statistically significant - (-0.09 (-0.24;0.05)), but not in subjects with normal glucose metabolism (0.01 (-0.10;0.12)) (P-value for interaction=0.02). No significant associations were observed for total, saturated fat and MUFA intake with LDL size. Intake of fat was associated with lag time; however, the small magnitude of the associations suggested that the composition of dietary fat is not a major factor affecting lag time. The same association with lag time was observed in all three glucose metabolism categories.

CONCLUSIONS

In individuals with abnormal glucose metabolism, higher PUFA intake is associated with smaller LDL particle size, but does not alter the susceptibility of LDL to in vitro oxidation.

SPONSORSHIP

Dutch Diabetes Research Foundation, and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO).

Thematic review series: Patient-Oriented Research. Design and analysis of lipoprotein tracer kinetics studies in humans

Lipoprotein tracer kinetics studies have for many years provided new and important knowledge of the metabolism of lipoproteins. Our understanding of kinetics defects in lipoprotein metabolism has resulted from the use of tracer kinetics studies and mathematical modeling. This review discusses all aspects of the performance of kinetics studies, including the development of hypotheses, experimental design, statistical considerations, tracer administration and sampling schedule, and the development of compartmental models for the interpretation of tracer data. In addition to providing insight into new metabolic pathways, such models provide quantitative information on the effect of interventions on lipoprotein metabolism. Compartment models are useful tools to describe experimental data but can also be used to aid in experimental design and hypothesis generation. The SAAM II program provides an easy-to-use interface with which to develop and test compartmental models against experimental models. The development of a model requires that certain checks be performed to ensure that the model describes the experimental data and that the model parameters can be estimated with precision. In addition to methodologic aspects, several compartment models of apoprotein and lipid metabolism are reviewed.

Ácidos graxos como marcadores biológicos da ingestão de gorduras

Os ácidos graxos da dieta têm sido associados ao desenvolvimento de doenças crônicas. Os inquéritos alimentares, utilizados em estudos clínicos e epidemiológicos para estimativa da ingestão de nutrientes, apresentam limitações na coleta de informações. Nesse sentido, a utilização da composição de ácidos graxos do plasma e do tecido adiposo como marcadores do tipo de gordura alimentar pode fornecer uma medida mais acurada da ingestão de gorduras. Esta pesquisa tem como objetivo evidenciar aspectos metabólicos de alguns ácidos graxos e o papel como marcadores da ingestão de gorduras, e apresentar as técnicas analíticas empregadas na sua determinação. A biópsia do tecido adiposo, com determinação da composição de ácidos graxos, fornece uma informação a longo prazo da ingestão de gorduras, enquanto que a avaliação da composição das frações lipídicas séricas representa a ingestão a curto e médio prazos. Os ácidos graxos essenciais, os ácidos graxos saturados com número ímpar de carbonos (15:0 e 17:0) e os ácidos graxos trans, por não apresentarem síntese endógena, são utilizados como marcadores biológicos da ingestão de gorduras ou de sua própria ingestão. As principais técnicas utilizadas para a determinação de ácidos graxos são a cromatografia gasosa e a cromatografia líquida de alta precisão. No presente momento, o uso de marcadores biológicos para a ingestão de gorduras, associados aos inquéritos alimentares, representa a forma mais completa de avaliação da ingestão de gorduras.

Aerobic exercise, lipoproteins, and cardiovascular disease: benefits and possible risks

Aerobic exercise has been shown to reduce the risk of cardiovascular disease (CVD). This reduction is proportional to the intensity of the exercise. The reduction in CVD risk is at least partially mediated by changes in circulating lipoproteins resulting from adaptive changes in enzymes involved in their metabolism. Specifically, aerobic exercise is associated with reductions in low density lipoprotein (LDL), total cholesterol and triacylglycerol (TAG), and increases in high density lipoprotein (HDL). Exposure to oxygen can oxidatively damage LDL. Oxidized LDL is a risk factor for atherosclerosis. Although aerobic exercise can cause oxidative damage, there are adaptive changes resulting from chronic exercise that result in lower rather than higher levels of oxidized LDL.

Exercise, postprandial triacylglyceridemia, and cardiovascular disease risk

An elevation of plasma triacylglycerides (TAG) is a well recognized cardiovascular risk factor. Less appreciated is that high and prolonged elevations in TAG in the postprandial (PP) phase is also a risk factor. Given that we spend approximately 18 hrs a day in the PP state, this is particularly critical. The elevation is due to both cylomicron and very low density lipoprotein TAG. It is thought that enhancing the concentrations of these lipoproprotein fractions increases the production of smaller, more dense low density lipoprotein and that this leads to increased cardiovascular disease risk. The PP TAG response is greater in men, in obese individuals, and in type 2 diabetics. It has been reported repeatedly that exercise the day before ingestion of a high fat meal is associated with a marked dampening of the PP TAG rise. The mechanisms for this are not clear and do not appear to be due to changes in the exercised muscle itself. There is some speculation that the production of plasma TAG may be decreased. The exercise benefits are lost within 3 days. The minimum exercise required has not been determined, but even 30 min of intermittent aerobic exercise or mild resistance exercise has a positive effect. This demonstrates a clear benefit from an active lifestyle and one that does not require intense exercise or months of training.

ApoE plasma levels and risk of cardiovascular mortality in old age

BACKGROUND

The epsilon2, epsilon3, and epsilon4 alleles of the apolipoprotein E gene (APOE) encode three isoforms, apoE2, E3, and E4, respectively. The apoE isoforms circulate in different plasma concentrations, but plasma concentrations of the same isoform also differ between individuals. Whereas the isoforms have been associated with cardiovascular disease, the relation between plasma apoE levels and cardiovascular disease is unknown.

METHODS AND FINDINGS

We assessed APOE genotypes, plasma levels of apoE, cardiovascular risk factors, and mortality in a population-based sample of 546 individuals aged 85 y who participated in the Leiden 85-plus Study and were prospectively followed for specific causes of death for 5 y. Participants in the highest tertile of apoE levels suffered a twofold-increased risk of cardiovascular mortality (hazard ratio compared to lowest tertile, 2.08; 95% confidence interval [CI], 1.30 to 3.33). Among the 324 participants with the epsilon3epsilon3 genotype, the hazard from cardiovascular disease was threefold increased (highest versus lowest tertile 3.01; 95% CI 1.60 to 5.66), with similar estimates for men and women. Other causes of death were not increased significantly. Plasma levels of apoE in epsilon3epsilon3 participants were positively correlated with total cholesterol (p < 0.001), low-density lipoprotein cholesterol (p < 0.001) and triglycerides (p < 0.001) and negatively with high-density lipoprotein cholesterol levels (p = 0.010). Adjustment for plasma lipids did not change the hazard ratios, whereas interaction was absent. The risk associated with high levels of apoE, however, was strongest in participants from the lowest tertile of C-reactive protein (CRP) levels and absent in those from the highest tertile (p(interaction) < 0.001). Among participants from the lowest tertile of CRP levels, those with a high apoE levels had a significantly steeper increase in CRP than those with low apoE levels (p = 0.020). Similar cardiovascular mortality risks as in epsilon3epsilon3 participants were found in epsilon2 and epsilon4 carriers.

CONCLUSIONS

In old age, high plasma apoE levels precede an increase of circulating CRP and strongly associates with cardiovascular mortality, independent of APOE genotype and plasma lipids.

The effects of low-fat, high-carbohydrate diets on plasma lipoproteins, weight loss, and heart disease risk reduction

Although there is consensus about restriction of dietary saturated and trans fatty acids, cholesterol, and sugars, there is debate about what the optimal total fat and carbohydrate content of the diet should be for weight loss and coronary heart disease (CHD) risk reduction. The overall evidence that dietary composition plays an important role in determining caloric intake is limited. Three recent randomized trials have indicated that low-carbohydrate diets are more effective in promoting weight loss in overweight and obese subjects over 4 to 6 months, but not over 1 year. In our own randomized trial no such differences were noted, and compliance with extreme diets was limited. Moreover little attempt has been made to control for the type of carbohydrate used in the low-fat, high-carbohydrate arms of these trials. Available evidence suggests that restriction of sugars and carbohydrates having a high glycemic index would be preferable to total carbohydrate restriction, and that an increased intake of fiber and essential fats (especially omega-3 fatty acids) is also important for overall heart disease risk reduction.

Smoking and development of type 2 diabetes in patients with decreased functional capacity

OBJECTIVE

Data regarding the possible contribution of cigarette smoking to development of type 2 diabetes are scarce and inconclusive. Patients with impaired functional capacity and diminished physical activity are prone to develop new diabetes. However, the role of smoking on diabetes incidence among these patients has not been specifically investigated. The present study was aimed to evaluate the association between cigarette smoking and development of type 2 diabetes in patients with coronary artery disease and decreased functional capacity over a 6.2-year follow-up period.

METHODS

The study sample comprised 630 nondiabetic patients aged 45-74 years, with a fasting blood glucose of <126 mg/dl and with impaired functional capacity (New York Heart Association functional class II and III). The sample was classified into two groups: 1) non smokers (never and past smokers pooled together)--552 patients and 2) current smokers--78 patients.

RESULTS

Smokers were younger but they had a relatively unfavorable lipid profile (with respect to apolipoproteins A, triglyceride and HDL-cholesterol levels). No significant differences between the groups were found for weight, body mass index, total cholesterol and blood pressure. During the follow-up, development of new diabetes was recorded in 98 patients: in 80 (14.5%) non smokers and in 18 (23.1%) smokers, p=0.05. Among the non smokers, there were no significant differences in diabetes incidence between 357 past smokers and 195 never smokers: respectively, 48 (13.4%) and 32 (16.4%), p=0.34. In addition, all-cause mortality among the smokers (23.1%) was significantly higher than in non smokers (12.7%), p=0.01. Multivariate analysis identified current smoking as an independent predictor of increased risk of new diabetes development with a hazard ratio of 1.94 (95% confidence interval 1.16-3.25).

CONCLUSIONS

Current smoking was associated with an independent two-fold increased risk for development of type 2 diabetes in patients with impaired functional capacity.

Dietary carbohydrate and cholesterol influence the number of particles and distributions of lipoprotein subfractions in guinea pigs

Guinea pigs (n=10/group) were fed one of three diets: a high carbohydrate (CHO) (42% energy), low cholesterol (0.04%) diet (LChHC), a diet with the same amount of CHO but with 0.25% cholesterol (HChHC) or a diet with 11% of energy from CHO and 0.25% cholesterol (HChLC) for 12 weeks. VLDL- and LDL cholesterol (LDL-C) were higher in the HChLC and HChHC groups than in the LChHC group (P<.0001). Lipoprotein subclasses and size were analyzed by nuclear magnetic resonance. Dietary cholesterol (HChHC and HChLC groups) resulted in larger VLDL particles (71.1+/-6.9, 78.9+/-3.33 nm, respectively) than those in the LChHC group (44.3+/-10.8 nm). In addition, there were higher concentrations of the large VLDL (>60 nm) and the medium VLDL (>35 nm) in the high cholesterol groups (P<.01). Similarly, the concentration of the medium (>8.2 nm) and small HDL (>7.2 nm) was higher in the HChHC and HChLC groups (P<.001). In contrast, CHO restriction affected the concentrations of LDL subfractions. The number of total LDL particles was lower in the HChLC (291.3+/-85.0 nmol/L) than in the HChHC group (467.6+/-113.1 nmol/L), indicating that the cholesterol in LDL was distributed in less particles in the former group. The concentrations of medium LDL (>19.8 nm) (98.4+/-90.8) and small LDL (>18 nm) (29.3+/-24.9 nmol/L) were lower in the HChLC group than in the HChHC group (261.8+/-105.8 and 64.9+/-27.9 nmol/L, respectively). These results indicate that dietary cholesterol increased the atherogenicity of both VLDL and HDL while CHO restriction increased the number of large LDL and decreased the concentrations of the more atherogenic smaller LDL subfractions.

Plant sterols as dietary adjuvants in the reduction of cardiovascular risk: theory and evidence

Plant sterol-enriched foods are an effective dietary adjuvant in reducing cardiovascular risk by lowering total cholesterol and low density lipoprotein-cholesterol (LDL-C) in serum by up to approximately 15%. The mechanism of action of plant sterols is different from those of 3-hydroxy-3-methylglutaryl coenzyme A inhibitors (statins) and thus their effect is additive. Combining plant sterols with other dietary components known to reduce cholesterol in a portfolio approach has proven to be most effective for reduction of hypercholesterolemia and provide an alternative treatment option for clinicians. Plant sterol-enriched foods provides clinicians with a relatively cheap, safe, and effective way to help patients manage their cardiovascular risk.

Endothelial Function in Healthy 11-Year-Old Children After Dietary Intervention With Onset in Infancy

Background— Early childhood introduction of nutritional habits aimed at atherosclerosis prevention reduces children’s serum total cholesterol concentration, but its effect on vascular endothelial function is unknown.

Methods and Results— Between 1990 and 1992, we randomized healthy 7-month-old infants (n=1062) to intervention (low-saturated-fat diet) and control (unrestricted diet) groups. At the age of 11 years, endothelium-dependent (flow-mediated) and endothelium-independent (nitrate-mediated) vasodilatory responses of the brachial artery were measured with high-resolution ultrasound in 179 intervention and 190 control children. The effect of intervention on endothelial function was significant in boys ( P =0.0034) but not in girls ( P =0.69). The maximum endothelium-dependent dilation response (mean±SD) was 9.62±3.53% and 8.36±3.85% in intervention boys and control boys and 8.84±4.00% and 8.44±3.60% in intervention girls and control girls, respectively. Intervention had no effect on nitrate-mediated dilation. The difference in endothelial function in boys remained significant after adjustment for current serum total or LDL cholesterol but became nonsignificant after adjustment for mean cholesterol measured under 3 years of age (adjusted means: 9.46% [CI 8.68% to 10.24%] versus 8.54% [CI 7.75% to 9.32%], P =0.11).

Conclusions— A low-saturated-fat diet introduced in infancy and maintained during the first decade of life is associated with enhanced endothelial function in boys. The effect is explained in part by the diet-induced reduction in serum cholesterol concentration.

Pureed cannellini beans can be substituted for shortening in brownies

Studies have shown white beans to be an effective fat replacer in dropped cookies. However, research is needed to determine whether legumes may be an effective replacement for fat in other types of cookies. This study determined the overall acceptability, sensory characteristics, and nutrient content of brownies (bar cookie) made using cannellini beans as a replacement for shortening. Cannellini beans were used to replace 25%, 50%, and 75% of the shortening (by weight) in a control brownie formula. One hundred twenty untrained panelists participated in rating the brownies on a seven-point hedonic scale. Analysis of variance conducted on the acceptability and sensory characteristics indicated a statistically significant effect when replacing fat with beans for acceptability, tenderness, texture, and flavor (P<.05). Post-hoc testing (Scheffe's test) indicated that neither the 25% nor the 50% bean brownies were significantly different from the control in overall acceptability, tenderness, texture, or flavor. Also, the 50% bean brownies, compared with control, had 2.6 g less fat and 21 fewer kcal per 1.4-oz serving. This study demonstrated that pureed cannellini beans can replace as much as 50% of the fat (by weight) in brownies, while yielding an acceptable and more nutritious product.

A mathematical model of fatty acid metabolism and VLDL assembly in human liver

The lipid composition of very-low-density lipoprotein (VLDL) in plasma is crucial for human health. A pre-requisite for the alteration of VLDL composition is a co-ordinated understanding of the complex interactions in VLDL assembly. In order to determine the potential effects of changes in substrate availability on VLDL lipid composition, we constructed, parameterized and evaluated a mechanistic mathematical model of the biosynthesis of triglycerides, phospholipids, and cholesterol esters and the assembly of VLDL in human hepatocytes. Using published data on human liver metabolism, the model was also used to provide insight into the complex process of lipid metabolism and to estimate the affinities of different liver enzymes for different fatty acids (FA). For example, we found that Delta6-desaturase is 19 times more selective for C18:3n-3 than C18:2n-6, stearoyl-CoA-desaturase is 2.7 times more selective for C18:0 than C16:0, Delta5-desaturase desaturates C20:4n-3 preferentially over C20:3n-6 and FA elongase preferentially elongates C18:3n-6. The model was also used to predict the plasma free fatty acid (FFA) composition required to generate a prescribed change in plasma lipoprotein FA composition. Furthermore, the model was tested against a published human feeding trial that investigated the effect of changes in dietary FA composition on human plasma lipid FA composition. The model is a useful tool for predicting the effect of changes in plasma FFA composition on plasma lipoprotein lipid FA composition.

Weight loss associated with reduced intake of carbohydrate reduces the atherogenicity of LDL in premenopausal women

The effect of a 3-tier intervention including dietary modifications (ie, moderate energy restriction, decreased carbohydrate, increased protein), increased physical activity, and the use of carnitine as a dietary supplement was evaluated on plasma lipids and the atherogenicity of low-density lipoprotein (LDL) particles in a population of overweight and obese premenopausal (aged 20-45 years) women. Carnitine or a placebo (cellulose) was randomly assigned to the participants using a double-blind design. Carnitine supplementation was postulated to enhance fat oxidation resulting in lower concentrations of plasma triglycerides. Seventy women completed the 10-week protocol, which followed a reduction in their energy intake by 15% and a macronutrient energy distribution of 30% protein, 30% fat, and 40% carbohydrate. In addition, subjects increased the number of steps taken per day by 4500. As no differences were observed between the carnitine and placebo groups in all the measured parameters, all subjects were pooled together for statistical analysis. Participants decreased (P<.01) their caloric intake (between 4132.8 and 7770 kJ) and followed prescribed dietary modifications as assessed by dietary records. The average number of steps increased from 8950+/-3432 to 12764+/-4642 (P<.001). Body weight, plasma total cholesterol, LDL cholesterol, and triglyceride were decreased by 4.5%, 8.0%, 12.3%, and 19.2% (P<.0001), respectively, after the intervention. Likewise, apolipoproteins B and E decreased by 4.5% and 15% (P<.05) after 10 weeks. The LDL mean particle size was increased from 26.74 to 26.86 nm (P<.01), and the percent of the smaller LDL subfraction (P<.05) was decreased by 26.5% (P<.05) after 10 weeks. In addition, LDL lag time increased by 9.3% (P<.01), and LDL conjugated diene formation decreased by 23% (P<.01), indicating that the susceptibility of LDL to oxidation was decreased after the intervention. This study suggests that moderate weight loss (<5% of body weight) associated with reduced caloric intake, lower dietary carbohydrate, and increased physical activity impacts the atherogenicity of LDL.

Grape polyphenols exert a cardioprotective effect in pre- and postmenopausal women by lowering plasma lipids and reducing oxidative stress

To evaluate the effects of grape polyphenols on plasma lipids, inflammatory cytokines, and oxidative stress, 24 pre- and 20 postmenopausal women were randomly assigned to consume 36 g of a lyophilized grape powder (LGP) or a placebo for 4 wk. The LGP consisted of 92% carbohydrate and was rich in flavans, anthocyanins, quercetin, myricetin, kaempferol, and resveratrol. After a 3-wk washout period, subjects were assigned to the alternate treatment for an additional 4 wk. The placebo consisted of an equal ratio of fructose and dextrose and was similar in appearance and energy content (554 kJ) to LGP. Plasma triglyceride concentrations were reduced by 15 and 6% in pre- and postmenopausal women, respectively (P < 0.01) after LGP supplementation. In addition, plasma LDL cholesterol and apolipoproteins B and E were lower due to LGP treatment (P < 0.05). Further, cholesterol ester transfer protein activity was decreased by approximately 15% with intake of LGP (P < 0.05). In contrast to these beneficial effects on plasma lipids, LDL oxidation was not modified by LGP treatment. However, whole-body oxidative stress as measured by urinary F(2)-isoprostanes was significantly reduced after LGP supplementation. LGP also decreased the levels of plasma tumor necrosis factor-alpha, which plays a major role in the inflammation process. Through alterations in lipoprotein metabolism, oxidative stress, and inflammatory markers, LGP intake beneficially affected key risk factors for coronary heart disease in both pre- and postmenopausal women.

Adiponectin, risk of coronary heart disease and correlations with cardiovascular risk markers

AIMS

We investigated the association of serum adiponectin concentrations with the risk of coronary heart disease (CHD) after careful adjustment for other established risk factors. In addition, we investigated the association between adiponectin levels and established sociodemographic and laboratory risk markers for CHD.

METHODS AND RESULTS

Three hundred and twelve patients aged 40-68 with angiographically confirmed stable CHD and 476 age- and gender-matched controls were included in this case-control study. Adiponectin serum concentrations (adiponectin, R&D Systems, Wiesbaden, Germany), markers of inflammation and haemostasis, and an extensive lipid profile were determined. Adiponectin serum concentrations were lower in CHD patients when compared with age- and gender-matched controls, both in men (median 4.95 vs. 5.58 micromol/L, P=0.004) and in women (median 9.64 vs. 11.60 micromol/L, P=0.018). Adiponectin was strongly correlated with lipoproteins and apolipoproteins, in particular HDL-cholesterol (HDL-C), and to a lesser degree with markers of inflammation such as C-reactive protein, IL-6, or markers of coagulation or fibrinolysis. When compared with subjects with adiponectin serum concentrations in the lower quintile, the OR for CHD was 0.52 (95% CI 0.28-0.95) in the upper one after adjustment for covariates (P<0.007 for trend). After additional adjustment for HDL-C the association was strongly reduced, reflecting the close association between adiponectin and HDL-C.

CONCLUSION

Adiponectin serum concentrations may have an important role in the development of CHD. The protective effect of high serum concentration may partly be mediated by effects on the metabolism of lipoproteins, especially on the metabolism of HDL.

Carbohydrate intake is correlated with biomarkers for coronary heart disease in a population of overweight premenopausal women

The associations between macronutrient intake and plasma parameters associated with increased risk for coronary heart disease (CHD) were evaluated in 80 overweight premenopausal women. We hypothesized that higher carbohydrate intake would be associated with a more detrimental plasma lipid profile. Dietary data were collected using a validated food frequency questionnaire (FFQ). Plasma total cholesterol (TC), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were determined from two fasting blood samples. In addition, selected apolipoproteins (apo) and LDL peak size were measured. Values for TC, TG and HDL were not in the range of risk classification; however, the mean values of LDL-C, 2.7 +/- 0.7 mmol/L, were higher than the current recommendations. Carbohydrate intake was positively associated with TG and apo C-III (P < .01) concentrations, and negatively associated with LDL diameter (P < .01). Participants were divided into low (<53% of energy) or high (> or = 53% energy) carbohydrate intake groups. Individuals in the <53% carbohydrate group consumed more cholesterol and total fat, but also had higher intake of polyunsaturated and monounsaturated fatty acids (SFAs). In contrast, subjects in the > or =53% group consumed higher concentrations of glucose and fructose than those in the low-carbohydrate (LC) group. In addition, subjects consuming <53% carbohydrate had lower concentrations of LDL-C and apo B (P < .01) and a larger LDL diameter (P < .05) than the > or =53% group. These results suggest that the lower LDL-C in the LC group may be related to both the amount of carbohydrate and the type of fatty acids consumed by these subjects.

Differential postprandial lipoprotein responses in type 2 diabetic men with and without clinical evidence of a former myocardial infarction

Postprandial lipemia plays an important role in the development of coronary heart disease through an elevation of triglyceride-rich lipoproteins. In type 2 diabetic male subjects, our aim was to compare postprandial lipemia in a high-risk population with former myocardial infarction (MI) with that of a lower risk population free of clinically detectable heart disease. 32 male type 2 diabetic subjects were included in the study. We matched 17 cases with a verified history of MI with 15 controls according to age, BMI, HbA1c, diabetes duration, smoking, and treatment of diabetes. Ongoing metformin, insulin, or lipid lowering pharmacological treatment were exclusion criteria. After a maximal exercise tolerance test and echocardiography, the subjects underwent a hyperinsulinemic, euglycemic clamp and a vitamin A fat loading test. Plasma triglyceride levels in the case group were significantly higher after 360 minutes (4.6 +/- 3.1 vs. 2.8 +/- 1.8 mmol/l, p = 0.04) and 480 minutes (3.6 +/- 2.2 vs. 2.4 +/- 2.4 mmol/l, p = 0.03), as was the incremental Area Under the Curve (iAUC) for the whole period (560 +/- 452 vs. 297 +/- 214 mmol x 480 min./l; p = 0.048). In addition, the retinyl palmitate responses in the chylomicron-fraction from the case group were significantly higher (iAUC 311,502 +/- 194,933 vs. 187,004 +/- 102,928 ng x 480 min./ml; p = 0.035). Type 2 diabetic males with prior MI had higher postprandial triglyceride-rich lipoprotein responses than those without MI, indicating that high responses may be a marker for a high-risk population.

Fatty acid composition and antioxidant properties of cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils

Cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils were evaluated for their fatty acid composition, carotenoid content, tocopherol profile, total phenolic content (TPC), oxidative stability index (OSI), peroxide value, and antioxidant properties. All tested seed oils contained significant levels of alpha-linolenic acid ranging from 19.6 to 32.4 g per 100 g of oil, along with a low ratio of n-6/n-3 fatty acids (1.64-3.99). The total carotenoid content ranged from 12.5 to 30.0 micromoles per kg oil. Zeaxanthin was the major carotenoid compound in all tested berry seed oils, along with beta-carotene, lutein, and cryptoxanthin. Total tocopherol was 260.6-2276.9 mumoles per kg oil, including alpha-, gamma-, and delta-tocopherols. OSI values were 20.07, 20.30, and 44.76 h for the marionberry, red raspberry, and boysenberry seed oils, respectively. The highest TPC of 2.0 mg gallic acid equivalents per gram of oil was observed in the red raspberry seed oil, while the strongest oxygen radical absorbance capacity was in boysenberry seed oil extract (77.9 micromol trolox equivalents per g oil). All tested berry seed oils directly reacted with and quenched DPPH radicals in a dose- and time-dependent manner. These data suggest that the cold-pressed berry seed oils may serve as potential dietary sources of tocopherols, carotenoids, and natural antioxidants.

Dietary factors and the regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase: Implications for breast cancer development

A role for mevalonate in cancer development has long been suggested by findings that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity is elevated in malignant cells. Increased synthesis mevalonate and mevalonate-derived nonsterol isoprenoids supports increased cell proliferation through the activation of growth-regulatory proteins and oncoproteins, and by promoting DNA synthesis. We have recently shown that mevalonate promotes the growth of human breast cancer cells both in culture and as tumors grown in nude mice. Inhibition mevalonate synthesis, therefore, may be an effective strategy to impair the growth of malignant breast cells. Several dietary compounds with known anti-cancer effects are also reported to inhibit HMG-CoA reductase activity. Here, we review evidence suggesting that inhibition of mevalonate synthesis may mediate the protective effects of cholesterol, plant isoprenoids, genistein, and long-chain n-3 polyunsaturated fatty acids (PUFAs) on experimental breast cancer.

Plant sterol/stanol prescription is an effective treatment strategy for managing hypercholesterolemia in outpatient clinical practice

OBJECTIVE

To determine the effectiveness of prescribing 2 g plant sterols/stanols per day as an addition to standard practice in a dietary outpatient clinic.

DESIGN

A randomized parallel design of comparative 12-week interventions.

SUBJECTS/SETTING

Patients referred by a general practitioner to a dietary outpatient clinic for the management of hyperlipidemia were eligible. Twenty-five patients (15 women and 10 men) completed the study.

INTERVENTION

Counseling regarding diet for hyperlipidemia was based on the National Cholesterol Education Program guidelines. The intervention group was instructed to incorporate approximately 25 g/day of margarine, containing plant sterols/stanols, which delivered approximately 2 g plant sterols/stanols.

MAIN OUTCOME MEASURE

Changes in diet, body weight, and serum total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides were measured.

STATISTICAL ANALYSIS PERFORMED

Changes in dietary and biochemical outcomes were assessed using Student's t test. For nonnormally distributed data, Wilcoxon signed rank test was used, and Mann-Whitney U tests were conducted to determine the proportion of subjects reaching defined goals. The number needed to treat index was used to report effectiveness of the intervention.

RESULTS

Five of 14 subjects in the intervention group compared with 0 of 11 in the control group achieved a reduction in serum cholesterol of >/=15% ( P <.05). Using the number needed to treat index, for each 2.8 patients counseled with routine prescription of plant sterols/stanols, one additional patient would obtain a reduction in cholesterol by >/=15% compared with conventional management. This was achieved without any detrimental effects on the dietary fatty acid profile.

CONCLUSIONS

Routine prescription of margarine containing plant sterol/stanol is an effective strategy in the management of hypercholesterolemic patients in the clinical setting.

Possible involvement of enhanced intestinal microsomal triglyceride transfer protein (MTP) gene expression in acceleration of lipid absorption by a western-type diet in apolipoprotein E knockout mice

Evidence has been accumulating that triglyceride (TG)-rich lipoproteins are atherogenic. Microsomal TG transfer protein (MTP) is essential for the synthesis of both chylomicron in the intestine and very low density lipoprotein in the liver. To investigate whether a western-type diet, a so-called atherogenic diet, alters intestinal lipid absorption via change in intestinal MTP expression, the effects of two different diet regimes in apolipoprotein-E knockout (apoE KO) mice were examined. Male apoE KO mice aged 6 weeks were fed a western-type diet or a chow diet for 5 weeks. Then, measurement of plasma TG levels after oral fat-loading and analysis of jejunal MTP gene expression were performed. Both the maximum level and the 0-8 h area under the curve (AUC) of the increase in TG levels in the western-type diet-fed mice were almost three times greater than those in the chow diet-fed mice. MTP gene expression, determined by reverse transcriptase-polymerase chain reaction (RT-PCR), was obviously enhanced in the western-type diet-fed mice compared to the chow diet-fed mice. These results suggest that the enhancement of intestinal MTP gene expression is involved in the accelerated lipid absorption in the western-type diet-fed mice.

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.

Aggressive diets and lipid responses

Poor diet and physical inactivity, the two major contributors to the development of overweight and obesity, have recently been identified as the second most common actual cause of death in the United States. With the increasing awareness of the strong link between obesity and chronic disease, in particular cardiovascular disease, a myriad of diets have surfaced and many of them claim weight loss depends more on the macronutrient composition of the diet than the number of calories consumed. Long-term outcome data, particularly cardiovascular outcome data, on these diets are sparse. This article summarizes previous and recent reports of popular and aggressive diets, such as low-carbohydrate diets, low-fat diets, and very low-calorie diets, addressing their effects on weight loss and focusing on their effects on lipids and lipoproteins.

Diet, genes and disease: implications for nutrition policy

There is extensive evidence to show that there is considerable variation in diet and disease patterns in Europe and that many of the dietary patterns are predictive of chronic disease. Increasingly, there is evidence that this dietary effect is mediated by genetic background. The present paper examines the role of polymorphisms within three genes, those responsible for the synthesis of apoE, 5,10-methylenetetrahydrofolate reductase (MTHFR) and PPARgamma. There is clear evidence to support the concept that the diet-disease link is moderated by genetic variation. The paper then considers whether this moderating effect will have implications for dietary recommendations. In the formulation of dietary reference values it has long been recognized that these values cannot cover the needs of all individuals. By setting the upper level at the mean value +2 sd, the needs of 97.5% of the population are covered. Setting a hypothetical scenario of a nutrient requirement of 200 mg/d and a polymorphism with an allelic frequency in the general population in the range of 0, 10, 20 and 30% that causes an increased nutrient requirement of 25%, there was no evidence that the traditional approach requires revision. Whilst it is recognized that genetic variability may not influence population goals, genetic variability will have to be taken into account in the clinical nutrition management of disease. To knowingly assign a patient to life-long treatment with a diet that for genetic reasons will have no success is both unethical and uneconomical. Once accepted in clinical nutrition, the diet-gene interaction will filter into the prevention of disease in public health nutrition.

Apolipoprotein A-I, B-100, and B-48 metabolism in subjects with chronic kidney disease, obesity, and the metabolic syndrome

The metabolism of apolipoproteins (apo)B-48, B-100, and A-I was studied with a primed constant infusion of deuterium-labeled leucine in the fed state in 3 male individuals with chronic kidney disease (CKD), a glomerular filtration rate (GFR) of 28 to 57 mL/min/1.73 m2, obesity (body mass index [BMI] 33.1), and the metabolic syndrome. Compared to 5 obese controls (BMI 30.1) and 13 non-obese controls (BMI 25.2), these CKD subjects had high plasma levels of triglycerides (TG) (343 +/- 27.5 mg/dL v 144 +/- 34.4 in the obese controls, P < .001) and low apoA-I (86.7 +/- 3.9 mg/dL). An abnormal high-density lipoprotein (HDL) particle subpopulation pattern was found, with low levels of pre beta-1 and alpha1. Compared to the obese controls, very-low-density lipoprotein (VLDL) and intermediate-density lipoprotein (IDL) apoB-100 levels were elevated 2- to 3-fold, while LDL apoB-100 levels were slightly lower (-7 %) and apoB-48 levels were comparable. The high TG levels were not associated with statistically significant changes in VLDL apoB-100 kinetics, although the production rate (PR) was higher and the fractional catabolic rate (FCR) was lower. The slightly lower LDL apoB-100 levels were accompanied by a significant 3-fold increase in the FCR and a 2.7-fold increase in the PR. The lower apoA-I levels were accompanied by a 1.6-fold increase in the FCR. Compared to the non-obese controls, the PR of apoA-I was increased by 61% and 38%, respectively (P < .001) in CKD and in obese control subjects. In the control subjects, the PR of apoA-I was significantly correlated with the BMI (r = 0.81, P < .0001). The kinetic results are consistent with these hypotheses: (1) CKD is associated with decreased clearance of the TG-rich lipoproteins (TRLs) and increased catabolism of LDL; (2) obesity increases apoB-100 and apoA-I production; and (3) in CKD, TG transfer to HDL, making HDL more susceptible to catabolism, accounts for the low apoA-I levels.

Dietary fiber and coronary disease: does the evidence support an association?

Large, prospective, epidemiologic studies show a protective effect of dietary fiber against coronary heart disease (CHD) and form the basis for new recommendations from the National Academy of Science for fiber intake (38 and 25 g/d for young men and women, respectively, based on an intake of 14 g of fiber per 1000 kcal). Mechanisms by which fibers may protect against CHD include lowering blood cholesterol (soluble fibers), attenuating blood triglyceride levels (mostly soluble fibers), decreasing hypertension (all fibers), and normalizing postprandial blood glucose levels (all fibers). An important consideration in making diet recommendations to protect against CHD is that the total amount of fiber from fiber-containing foods is important, and individuals should not just be counseled to focus on soluble fiber.

Effects of a low-fat vegan diet and a Step II diet on macro- and micronutrient intakes in overweight postmenopausal women

OBJECTIVE

This study investigated the nutrient intake of overweight postmenopausal women assigned to a low-fat vegan diet or a Step II diet.

METHODS

Fifty-nine overweight (body mass index, 26 to 44 kg/m2) postmenopausal women were randomly assigned to a self-selected low-fat vegan or a National Cholesterol Education Program Step II diet in a 14-wk controlled trial on weight loss and metabolism. Nutrient intake, which was measured per 1000 kcal, was the main outcome measure. Statistical analyses included within-group and between-group t tests examining changes associated with each diet.

RESULTS

Consumption of a low-fat vegan diet was associated with greater decreases in fat, saturated fat, protein, and cholesterol intakes and greater increases in carbohydrate, fiber, beta-carotene, and total vitamin A intakes than was a Step II diet. The low-fat vegan group also increased thiamin, vitamin B6, and magnesium intakes more than the Step II group, and both groups increased folic acid, vitamin C, and potassium intakes. If considering only food sources of micronutrients, the low-fat vegan group decreased vitamin D, vitamin B12, calcium, selenium, phosphorous, and zinc intakes compared with baseline. However, with incidental supplements included, decreases were evident only in phosphorous and selenium intakes. No micronutrient decreases were found in the Step II group.

CONCLUSIONS

Individuals on a low-fat vegan or Step II diet should take steps to meet the recommended intakes of vitamin D, vitamin K, folic acid, calcium, magnesium, and zinc. Individuals on a low-fat vegan diet should also ensure adequate intakes of vitamin B12, phosphorous, and selenium.