Associations between dietary factors and serum lipids by apolipoprotein E polymorphism

Dietary recommendations for dysbetalipoproteinemia: A need for better evidence

The increased risk of cardiovascular disease in patients with dysbetalipoproteinemia (DBL) is well documented and is associated with the dysfunctional metabolism of remnant lipoproteins. Although these patients are known to respond well to lipid-lowering medication including statins and fibrates, the best dietary approach to lower remnant lipoprotein accumulation and to prevent cardiovascular outcomes remain unclear. Indeed, current evidence is based on studies published mainly in the 1970s, which comprise small sample sizes and methodological limitations. This review aims to summarize nutritional studies performed in DBL patients to date and to discuss potential avenues in this field and future areas of research.

Epicardial adipose tissue and signs of metabolic syndrome in children

PURPOSE

The aim of this study was to investigate the possible correlation between epicardial adipose tissue (EAT) thickness and predictive parameters for metabolic syndrome (MS) in overweight/obese prepubertal children.

METHODS

73 prepubertal children, average age of 8.22 years, with no endocrine or syndromic causes of obesity or under drug therapy for chronic disease were enrolled. Weight, height, body circumferences and skinfolds' thickness were measured. BMI, BMI z score (z-BMI) and waist-to-height ratio (WtHR) were calculated. Standard MS-related laboratory parameters were assessed. Finally, all children underwent echocardiographic measurement of EAT.

RESULTS

A positive correlation between EAT and z-BMI was found only among overweight/obese children (r = 0.43, p = 0.001). In particular, data showed that 89 % of our sample had a waist (W) >90th percentile. Statistical differences in diastolic blood pressure (DBP; p < 0.01) and EAT (p = 0.02) were observed on comparing W <90th percentile vs W >90th percentile patients. Besides, in patients with W >90th percentile and family history of risk factors for MS, the value of EAT correlated positively with z-BMI, W, WtHR, triglycerides (Tg), insulin and homeostatic model assessment of insulin resistance and negatively with HDL.

CONCLUSIONS

The EAT and the markers of MS probably share the same pathogenetic factors. Further studies might elucidate whether EAT deserves to be included among the diagnostic factors of MS.

Impact of genetic variants in human scavenger receptor class B type I (SCARB1) on plasma lipid traits

BACKGROUND

Scavenger receptor class B type 1 (SCARB1) plays an important role in high-density lipoprotein cholesterol (HDL-C) metabolism in selective cholesteryl ester uptake and in free cholesterol cellular efflux.

METHODS AND RESULTS

This study aims to identify common (minor allele frequency ≥5%) and low-frequency/rare (minor allele frequency <5%) variants, using resequencing all 13 exons and exon-intron boundaries of SCARB1 in 95 individuals with extreme HDL-C levels selected from a population-based sample of 623 US non-Hispanic whites. The sequencing step identified 44 variants, of which 11 were novel with minor allele frequency <1%. Seventy-six variants (40 sequence variants, 32 common HapMap tag single nucleotide polymorphisms, and 4 relevant variants) were selected for genotyping in the total sample of 623 subjects followed by association analyses with lipid traits. Seven variants were nominally associated with apolipoprotein B (apoB; n=4) or HDL-C (n=3; P<0.05). Three variants associated with apoB remained significant after controlling false discovery rate. The most significant association was observed between rs4765615 and apoB (P=0.0059), while rs11057844 showed the strongest association with HDL-C (P=0.0035). A set of 17 rare variants (minor allele frequency ≤1%) showed significant association with apoB (P=0.0284). Haplotype analysis revealed 4 regions significantly associated with either apoB or HDL-C.

CONCLUSIONS

Our findings provide new information about the genetic role of SCARB1 in affecting plasma apoB levels in addition to its established role in HDL-C metabolism.

Amyloid-beta (Aβ1-42)-induced paralysis in Caenorhabditis elegans is reduced by restricted cholesterol supply

Alzheimer' disease is a neurodegenerative disorder characterized by the misfolding and aggregation of amyloid β (Aβ). This process is influenced through supply of cholesterol via apolipoproteins to neurons. In the present study, we used the transgenic Caenorhabditis elegans strain CL2006, which expresses Aβ1-42 under control of a muscle-specific promoter, to test the effects of the apolipoprotein B homologue vitellogenin-6 on paralysis. Knockdown of vitellogenin-6 using RNA-interference (RNAi) recently was shown to significantly reduce cholesterol absorption in C. elegans, and both, RNAi for vitellogenin-6 or lowering the cholesterol concentration in the medium was associated with reduced Aβ-aggregation and paralysis in the nematodes. The effects of both interventions are mediated through the inhibition of the steroidal-signaling pathway since knockdown of its key factors DAF-9 or DAF-12 reduced paralysis independent of the cholesterol concentration and without additive effects by vitellogenin-6 RNAi. Double-RNAi for daf-12 and the downstream target of insulin-signaling, the foxo transcription factor daf-16, revealed that the paralysis-triggering effects of daf-16 RNAi were dominant over the preventive effects of daf-12 RNAi. Identical observations were made when the transcriptional co-activators of DAF-16, ftt-2 or par-5 were knocked down instead of daf-16. In conclusion, interactions between the steroidal and insulin-signaling pathways were identified in Aβ1-42 expressing CL2006, where cholesterol deprivation inhibits steroidal-signaling and thereby activates DAF-16-signaling. Those effects were associated with a reduced Alzheimer phenotype in the nematodes, i.e. reduced protein aggregation and paralysis.

Is carbohydrate intake in the first years of life related to future risk of NCDs?

Studies on children's carbohydrate intake, especially fibre intake, and its associations with later health are rare. The current recommendations for fibre intake in children are based on average assumptions and data extrapolated from intakes in adults. Generally, increase in whole-grain consumption and decrease in sucrose intake are considered healthy. Due to fibre's high bulk volume however, excessive dietary fibre has been feared to decrease energy density have effects on growth, at least in developing countries and in children consuming very restricted diets. Furthermore, it has been speculated that if fats are reduced from the diet, it may become high in sucrose. In STRIP study, which is a long-term, randomized controlled trial designed to decrease the exposure of children to known risk factors of atherosclerosis, carbohydrate intakes have been investigated in detail in children aged 13 months to 9 years. The intervention was successful in decreasing saturated fat intake and cholesterol concentrations throughout childhood and adolescence. The study results also show that a higher than average fibre intake does not displace energy or disturb growth in children and that children with high fibre intake have better dietary quality than those with low fibre intake. Dietary fibre intake associated with lower serum total cholesterol concentrations whereas increases in total carbohydrate, sucrose and fructose intakes associated with increases in serum triglyceride concentrations. In conclusion, from the point of view of CHD risk factor prevention, efforts aiming at increasing the fibre intake while restricting that of refined sugar seem justified in the child population in developed countries.

CLINICAL TRIAL REGISTRATION INFORMATION

NCT00223600.

Urinary enterolignan concentrations are positively associated with serum HDL cholesterol and negatively associated with serum triglycerides in U.S. adults

Fiber-rich diets are associated with favorable lipid profiles, but the specific compounds and the mechanisms behind this effect are yet to be fully understood. Lignans are fiber-related polyphenols that have been associated with lower prevalence of cardiovascular disease. The objective of this study was to investigate the relationship between dietary lignan exposure, measured as the urinary concentration of their metabolites, enterolactone and enterodiol, and serum lipids in a representative sample of U.S. adults. We carried out a cross-sectional analysis of data from 1492 adults who participated in the 1999-2004 NHANES. The mean urinary concentration of enterolignans in U.S. adults was 1.9 μmol/L. The multivariate-adjusted mean differences comparing the highest and lowest enterolignan tertile were 0.06 mmol/L for HDL cholesterol and -0.17 mmol/L for TG (P < 0.05). In spline regression models, we also found an inverse association between serum TG and urinary enterolignan concentrations. Serum HDL cholesterol levels increased linearly with increasing enterolignan concentrations. Modest or no associations were found between enterolignan concentrations and serum LDL cholesterol or total cholesterol. In conclusion, enterolignan concentrations are associated with lower serum TG concentrations and greater HDL cholesterol concentrations in U.S. adults.

Neuronutrition and Alzheimer's disease

Alzheimer's disease (AD) is a complex neurological disorder resulting from both genetic and environmental factors with the latter being particularly important for the sporadic form of the disease. As such, diets rich in saturated fatty acids and alcohol, and deficient in antioxidants and vitamins appear to promote the onset of the disease, while diets rich in unsaturated fatty acids, vitamins, antioxidants, and wine likely suppress its onset. In addition, evidence suggests that diets rich in polyphenols and some spices suppress the onset of AD by scavenging free radicals and preventing oxidative damage. Metal ions are known to catalyze the production of free radicals and induce mental retardation or dementia, and several studies have also identified metals such as Pb, Fe, Al, Cu, and Zn in AD pathogenesis. While specific metal chelators have been tested for therapy, they have not been very successful, probably due to their late administration, i.e., after brain damage has been triggered. Since several dietary polyphenols are known to chelate metals, their routine use may also be protective against the onset of AD. In this review, we summarize beneficial dietary techniques in the fight against AD.

Dietary fiber does not displace energy but is associated with decreased serum cholesterol concentrations in healthy children

BACKGROUND

Dietary fiber has health benefits, but fiber recommendations for children are controversial because fiber may displace energy.

OBJECTIVE

The objective was to longitudinally evaluate dietary fiber intake in children and to study associations between growth variables, serum cholesterol concentrations, and intakes of fiber, energy, and nutrients.

DESIGN

Altogether, 543 children from a prospective randomized atherosclerosis prevention trial (the Special Turku Coronary Risk factor Intervention Project; STRIP) participated in this study between the ages of 8 mo and 9 y. The intervention children (n = 264) were counseled to replace part of saturated fat with unsaturated fat. Nutrient intakes, weight, height, and serum total, HDL-, and LDL-cholesterol and triglyceride concentrations were analyzed. Children were divided into 3 groups according to mean dietary fiber intake in foods: low (lowest 10%), high (highest 10%), and average (middle 80%) fiber intakes.

RESULTS

Fiber intake associated positively with energy intake and inversely with fat intake. Children with a high fiber intake received more vitamins and minerals than did children in other groups. In longitudinal growth analyses, weights and heights were similar in all 3 fiber intake groups, and fiber intake (g/d) associated positively with weight gain between 8 mo and 2 y. Serum cholesterol concentrations decreased with increasing fiber intakes. Children in the intervention group had a higher fiber intake than did the control children during the entire follow-up period.

CONCLUSION

Fiber intake did not displace energy or disturb growth between 13 mo and 9 y of age. Serum cholesterol values correlated inversely with fiber intake, which indicated that part of the cholesterol-lowering intervention effect in the STRIP project may have been explained by dietary fiber.

Carbohydrate intake, serum lipids and apolipoprotein E phenotype show association in children

AIM

To study the association between carbohydrate intake and serum lipids in children, and influence of apolipoprotein E phenotype (apoE) on the association.

SUBJECTS/METHODS

A total of 644 children from a prospective, randomized atherosclerosis prevention trial (STRIP) participated in this longitudinal study at age 5 (n = 644), 7 (n = 585) and 9 (n = 550) years. ApoE phenotype, fasting triglyceride, total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol concentrations and 4-day food records were analysed.

RESULTS

An increase in the total carbohydrate intake by 1 E% (percentage of total daily energy intake) associated with a decrease in HDL cholesterol by 0.006 mmol/L (p < 0.001) when adjusted for saturated, monounsaturated and polyunsaturated fatty acid, age, gender, body mass index and STRIP study group. The inverse association between total carbohydrate intake and HDL cholesterol was evident in children with apoE3 (p < 0.001) or apoE4 (p < 0.001), but not in those with apoE2 (p = 0.78). An increase in total carbohydrate intake by 1 E% increased triglycerides by 0.02 mmol/L (p < 0.001) independently of apoE phenotype, while 1 E% increase in sucrose intake increased triglycerides by 0.01 mmol/L (p < 0.001).

CONCLUSION

Carbohydrate intake has a relatively small effect on serum lipids in children. Children with the apoE3 or E4 but not with E2 phenotype show reduction in HDL cholesterol with increasing carbohydrate intake indicating that genetic and environmental factors interact with children's lipoprotein metabolism.

The relationship between nutrient intake and cognitive performance in people at risk of dementia

BACKGROUND

There is evidence of a link between nutrient intake and cognitive impairment and decline in old age. There has been no study of nutrient intake in Irish subjects at risk of dementia.

AIM

To investigate the possible link between nutrient intake and cognitive performance in a group of Irish adults at risk of dementia, and to compare the nutrient intake in these adults stratified by the absence or presence of the apolipoprotein E (APOE) epsilon4 allele.

METHOD

Forty-four subjects, who were first-degree blood relatives of people with Alzheimer's disease, were recruited. Cognitive performance and nutritional intake were assessed and apolipoprotein E (APOE) genotype determined.

RESULTS

The intakes of cholesterol (P < 0.037) and Na (P < 0.037) were significantly higher in subjects with altered cognitive performance. There was no significant difference in nutrient intakes between APOE epsilon-4 allele positive and APOE epsilon-4 allele negative subjects.

CONCLUSION

The findings of this work suggest that dietary cholesterol and sodium intake may be linked to cognitive impairment.

Lipids, diet and Alzheimer disease: an extended summary

A number of dietary elements and foods have been reported to be either risk or protective factors for the development of dementia and Alzheimer disease (AD). These include fat, fatty acids, antioxidants, fish, homocysteine/methionine, vitamins and alcohol. We propose that brain diseases with aging are not be only the result of pathogenic processes, but also due to the failure of protective mechanisms, and that diet influences the success of these protective mechanisms. Both animals and humans with genetic forms of AD do not get the disease until a certain time in mid or late life. Therefore, there must be protective factors responsible for the delayed onset of disease.

Genetic variation in uncoupling protein 3 is associated with dietary intake and body composition in females

The uncoupling proteins (UCPs) are a family of mitochondrial transport proteins that promote proton leakage across the inner mitochondrial membrane, uncoupling oxidative phosphorylation from adenosine triphosphate (ATP) production and releasing energy as heat. Variation in these genes may disrupt biochemical pathways influencing thermogenesis, energy metabolism, and fuel substrate partitioning and oxidation, which may in turn predispose to obesity. We genotyped polymorphisms in UCP2 and UCP3 in a sample of nondiabetic participants (n = 722) of the San Luis Valley Diabetes Study (SLVDS) and found female-specific associations between UCP3 polymorphisms and measures of dietary intake and body composition. The UCP3-5 variant was statistically significantly associated with total caloric intake (P =.012), fat intake (P =.011), fat mass (P =.004), and lean mass (P =.013), with the C allele corresponding to higher dietary intake and lower fat mass and lean mass. The UCP3p-55 and the UCP3-3 polymorphisms, which were in high linkage disequilibrium (D' = 0.9776), showed similar patterns of association with total caloric intake (P =.031 and P =.042, respectively) and lean mass (P =.035 and P =.059, respectively), with the rare alleles corresponding to higher total intake and lean mass. No statistically significant associations were detected between the outcome variables and polymorphisms in UCP2. Two-way analysis of covariance (ANCOVA), used to evaluate the multi-locus effects and interactions between UCP3-5 and UCP3p-55, showed association with the main effect terms, but no evidence for statistically significant interaction between UCP3-5 and UCP3p-55 in regard to dietary intake. The UCP3-5 polymorphism was the only statistically significant genetic predictor of fat mass. The lean mass model showed no statistically significant association with either UCP3 variant. These results support a role for UCP3 in fuel substrate management and energy metabolism, which may influence body weight regulation.

The epsilon4 allele of apolipoprotein E gene is a potential risk factor for the severity of macular edema in type 2 diabetic Mexican patients

PURPOSE

The objective of this study was to determine the relationship between APOE polymorphism and the severity of retinal hard exudates in Mexican patients with type 2 diabetes.

METHODS

We studied 36 patients with diabetic retinopathy and 22 unrelated and apparently healthy age-matched individuals. Blood samples for DNA genotyping and lipid profile were taken. Genotyping of polymorphic APOE alleles was done after polymerase chain reaction amplification of genomic DNA, digestion with HhaI, and agarose gel electrophoresis. Stereoscopic 35 degrees color fundus photographs were taken of seven standard fields. Diabetic retinopathy, macular edema and hard exudates were graded according to a standardized procedure.

RESULTS

The results showed that the lipid profile was higher but not statistically significant (p > 0.05) in e4 allele carriers, with the exception of total lipids (p > 0.05). The frequency of severe retinal hard exudates was higher in those epsilon4 allele carriers (p < 0.05). The higher frequency of visual impairment (VA < 0.5 Log MAR) in epsilon4 carriers showed a tendency towards statistical significance (p = 0.057).

CONCLUSION

Our results suggest that the epsilon4 allele of the ApoE gene is a potential risk factor for the severity of retinal hard exudates and visual loss in type 2 diabetic Mexican patients with diabetic retinopathy.

APOE polymorphism and the hypertriglyceridemic effect of dietary sucrose

BACKGROUND

The E4 allele of the apolipoprotein gene (APOE) is associated with a greater serum cholesterol response to dietary changes in fat and cholesterol. However, less is known about the interaction between APOE polymorphism and other macronutrients in the diet.

OBJECTIVE

We evaluated the interaction between APOE polymorphism and dietary fat and carbohydrate, particularly sucrose, in relation to serum lipid concentrations.

DESIGN

A total of 284 men and 130 women with coronary artery disease (mean age: 61 y; range: 33-74 y) participated in the cross-sectional EUROASPIRE study. Serum lipids and fatty acids in cholesteryl esters (CEs) were measured and APOE genotypes were determined. Dietary intake was examined by using a 4-d food record.

RESULTS

Patients were grouped by APOE genotype: E2 (E2/E2 and E2/E3; n = 21), E3 (E3/E3; n = 245), and E4 (E4/E2, E4/E3, and E4/E4; n = 148). Patients with the E2 allele had lower LDL-cholesterol concentrations and tended to have higher triacylglycerol concentrations than did patients with the E3 or E4 allele; concentrations were not significantly different between the last 2 groups. In regression analysis, significant predictors of serum triacylglycerol were the interaction between sucrose intake and the E2 allele, proportion of n-3 fatty acids in CEs, body mass index, and diabetes. A high sucrose intake was associated with high triacylglycerol concentrations only in patients with the E2 allele. Interaction between saturated fat intake and the E2 allele, proportion of linoleic acid in CEs, and fiber intake predicted serum cholesterol.

CONCLUSION

Coronary artery disease patients with the E2 allele will likely have a greater triacylglycerol response to high dietary sucrose intakes than will patients with the E3 or E4 allele.

Apolipoprotein B gene polymorphisms and serum lipids: meta-analysis of the role of genetic variation in responsiveness to diet

BACKGROUND

The genetic variance determining plasma lipid and lipoprotein concentrations may modify individual responsiveness to alterations in dietary fat and cholesterol content.

OBJECTIVE

The aim was to examine the role of apolipoprotein (apo) B DNA polymorphisms in responsiveness of plasma lipids and lipoproteins to diet.

DESIGN

A controlled dietary intervention study was conducted in 44 healthy, middle-aged subjects with a 3-mo baseline, a 1-mo fat-controlled, a 1-mo high-fat, and a 1-mo habitual diet period. We also conducted a meta-analysis of all published dietary trials, including our own.

RESULTS

In our own dietary study, the apo B XbaI restriction-site polymorphism affected the responsiveness to diet of the plasma LDL-cholesterol concentration (P < 0.05, repeated-measures analysis of variance). Especially during the high-fat diet, homozygous absence of the XbaI restriction site (X(-)/X(-)) was associated with a greater increase in LDL cholesterol (44 +/- 5%) than was X(+)/X(+) (27 +/- 7%) or X(+)/X(-) (40 +/- 5%). The high-fat diet also induced a larger increase in plasma LDL cholesterol in subjects with the R(-)/R(-) genotype (homozygous absence of the EcoRI restriction site) (59 +/- 10%) than in those with the R(+)/R(-) (39 +/- 6%) or R(+)/R(+) (36 +/- 4%) genotype. The M(+)/M(+) genotype (homozygous presence of the MspI restriction site) was also more responsive (41 +/- 3% increase in LDL cholesterol) than the M(+)/M(-) genotype (27 +/- 10% increase). The meta-analysis supported the finding of the significant role of the EcoRI and MspI polymorphisms, but not that of the XbaI polymorphism.

CONCLUSIONS

The present study indicated that the apo B EcoRI and MspI polymorphisms are associated with responsiveness to diet.

Apolipoprotein E genotype modulates the effect of black tea drinking on blood lipids and blood coagulation factors: a pilot study

Apolipoprotein E (ApoE) genotype was determined in sixty-five subjects who had taken part in a 4-week randomized crossover trial to compare the effect of six mugs of black tea per day v. placebo on blood lipids and blood coagulation factors. Four ApoE genotype variants (seven E2/E3, forty-five E3/E3, twelve E3/E4 and one E4/E4) were found. ApoE allele frequency was within the range typical for Caucasian populations (ApoE-E2 5.4%; ApoE-E3 83.8%; ApoE-E4 10.8%). Individuals bearing at least one E4 allele had substantially higher levels of serum total cholesterol, LDL cholesterol and triacylglycerols. Mean plasminogen activator inhibitor (PAI-1) activity was higher in ApoE-E4 allele-bearing individuals (E3/E4 + E4/E4, 11.89 (SE 1.27) U/ml; E3/E3, 9.19 (SE 0.80) U/ml; E2/E3, 7.21 (SE 1.04) U/ml, P values of E4-group v. E3 and E2 being respectively 0.093 and 0.030). These unexpected findings imply that elevated PAI-1 activity may be a hitherto unrecognized additional factor involved in the increased cardiovascular disease risk associated with apoE-E4 allele. The interactions between tea drinking and genotype were also examined. In the E3/E3 homozygotes, HDL-cholesterol was significantly reduced in the tea period (mean placebo 1.54 mmol/l v. mean tea 1.50 mmol/l, P = 0.027). In the E2/E3 group, triacylglycerol concentration was significantly reduced (mean placebo 1.18 mmol/l v. mean tea 1.09 mmol/l, P = 0.039). Tea also caused a significant decrease of PAI-1 activity in the subjects with E2/E3 genotype (mean placebo 7.21 U/ml v. mean tea 5.88 U/ml, P = 0.007). In the other two genotype groups, there was no significant effect of tea. The results indicate that tea drinking has a beneficial effect on some cardiovascular disease risk-associated factors, especially in E2 allele-bearing individuals. Dietary intervention may be particularly effective in population groups with certain genetic characteristics.

Interactions between lifestyle-related factors and the ApoE polymorphism on plasma lipids and apolipoproteins. The EARS Study. European Atherosclerosis Research Study

To elucidate how the apolipoprotein (apo) E polymorphism and modifiable factors interact in explaining plasma lipid and apolipoprotein levels, we studied 1448 young adults (18 to 26 years old), participating in the European Atherosclerosis Research Study (EARS). Venous blood was collected after an overnight fast. Modifiable factors, eg, body mass index (BMI), waist-to-hip ratio (WHR), tobacco and alcohol consumption, and physical activity, were determined by using standardized protocols. Associations of modifiable factors with apoE levels were homogeneous across apoE phenotypes. In contrast, correlations of BMI with total cholesterol and apoB levels, as well as correlations between WHR and apoB, were significantly (P < .05 to P < .01) stronger in E2 carriers than in subjects with other phenotypes. Total cholesterol and apoB levels were comparable in E2 carriers in the upper tertile of BMI or WHR to those in E3/3 subjects, suggesting that the lowering effect of the E2 allele was no longer present. The inverse association between the plasma cholesteryl linoleate-to-oleate ratio, a marker for the dietary polyunsaturated-to-saturated fatty acid ratio, and triglycerides was also stronger in E2 carriers (-0.33 versus -0.17 in E3/3 and -0.24 in E4 carriers). Associations with other modifiable factors were notably consistent across apoE phenotypes. Gender and modifiable factors explained three times more (31%) of the interindividual variation in apoB levels in E2 carriers than in E3/3 subjects (9%) or E4 carriers (14%), mainly due to a larger variance explained by BMI. Our results suggest that the apoE polymorphism acts in a relatively uniform manner, independently of lifestyle. However, the associations of adiposity to total cholesterol and apoB levels appear to be stronger in apoE2 carriers.