Apolipoprotein E and diets: a case of gene-nutrient interaction?

APOE-Genotype and Insulin Modulate Estimated Effect of Dietary Macronutrients on Cognitive Performance: Panel Analyses in Nondiabetic Older Adults at Risk of Dementia

BACKGROUND

The apolipoprotein E gene (APOE ε-2/3/4, combined as 6 different genotypes: ε-22/23/24/33/34/44) and insulin status modulate dementia risk and play a role in the metabolism of macronutrients.

OBJECTIVES

We aimed to examine APOE-genotype and fasting insulin as effect modifiers of the slopes between dietary macronutrients and cognitive performance among older adults at risk of dementia.

METHODS

Panel analyses-with diet and cognition measured at baseline and follow-up at years 1 and 2-were performed in a sub-sample from the FINGER (Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability) trial (n = 676, 60-77 y, 46% females, all nondiabetics). The associations between macronutrients (3-d food records, z-scores) and global cognition (modified Neuropsychological Test Battery, z-score) were analyzed in mixed regression models adjusted for confounders selected a priori. After a gradient was implied by the point estimates in categorical APOE analyses, we investigated a continuous APOE variable [APOE-gradient, coded -1 (for ε-23), -0.5 (ε-24), 0 (ε-33), 1 (ε-34), 2 (ε-44)] as an effect-modifier.

RESULTS

At increasing levels of the APOE-gradient, a relatively more favorable slope between diet and cognition was observed for a lower carbohydrate/fat ratio [β = -0.040, 95% confidence interval (CI): -0.074, -0.006; P = 0.020 for interaction diet × APOE-gradient), and higher protein (β = 0.075, 95% CI: 0.042, 0.109; P = 9.4 × 10-6). Insulin concentration (log-linear) modulated the association between the carbohydrate/fat ratio and cognition by a quadratic interaction (β = -0.016, P = 0.039). Coherent findings for exploratory predictors (fiber, fat subtypes, composite score, metabolic biomarkers) were compatible with published hypotheses of differential dietary adaptation by APOE, with cognition among ε-33 being relatively independent of dietary parameters-implying "metabolic flexibility." Antagonistic slopes to cognition for ε-23 (positive) compared with ε-34 and ε-44 (negative) were found for a Higher-carbohydrates-fiber-Lower-fat-protein composite score, even as within-subjects effects.

CONCLUSIONS

APOE-based precision nutrition appears conceptually promising, but replications in wider samples are warranted, as well as support from trials. Both relative hyper- and hypoinsulinemia might modulate the effect of diet on cognition.

A Scoping Review of Dietary Factors Conferring Risk or Protection for Cognitive Decline in APOE ε4 Carriers

Alzheimer's disease (AD) is a progressive and fatal neurodegenerative disease. The strongest genetic risk factor for sporadic AD is carriage of the ε4 allele of the Apolipoprotein E (APOE) gene. Strategies to slow the progression of AD, including dietary interventions, may be modified by the pathogenic effect of this polymorphism. Our objective in this review was to determine the extent and quality of the literature investigating how dietary factors and interventions interact with the APOE ε4 genotype to impact cognitive decline in AD. To that end, we performed a systematic scoping review of published English-language articles involving human subjects. We found evidence suggesting that adherence to a Mediterranean diet may reduce cognitive decline among APOE ε4 carriers, whereas ketogenic agents appear to be ineffective. Diets high in saturated fats may be particularly harmful for APOE ε4 carriers. We identified several topics, including the use of ω-3 fatty acid and antioxidant supplements, for which additional high level evidence is needed.

Apolipoprotein E4 mediates insulin resistance-associated cerebrovascular dysfunction and the post-prandial response

Metabolic dysfunction, commonly a result of diets high in saturated fats and sugar, is associated with impaired cognitive function and an increased risk of age-related cognitive decline (ACD) and Alzheimer's disease (AD). Compared to the E3 isoform of apolipoprotein (apoE), the E4 isoform is a major genetic risk factor for ACD, AD, and for developing cognitive impairments following various environmental challenges, including dietary challenges such as a high-fat diet (HFD). Both insulin resistance (IR) and E4 are associated with metabolic and vascular impairments. Deficits in cerebral metabolism and cerebrovascular function have been proposed as initiating events leading to these impairments. In the current study, we employed a model of human apoE targeted replacement mice and HFD-induced obesity to study the potential link between E4 and IR, at rest and following a postprandial challenge. HFD-induced IR was associated with impaired cognition, reduced cerebral blood volume and decreased glucose uptake. These effects were more profound in E4 than E3 mice. Furthermore, the cognitive, metabolic and cerebrovascular responses to an exogenous glucose load showed an apoE isoform-dependent response, with E4, but not E3 mice, acutely benefiting from a spike in blood glucose.

Association of APOE gene polymorphism with lipid profile and coronary artery disease in Afro-Caribbeans

OBJECTIVES

Apolipoprotein E gene (APOE) polymorphism is associated with the lipid profile and cardio-vascular disease. However, these relationships vary between ethnic groups. We evaluated, for the first time in an Afro-Caribbean population, the distribution of APOE polymorphisms and their associations with coronary artery disease (CAD), the lipid profile and other cardio-metabolic risk factors.

METHODS

We studied 712 Afro-Caribbean subjects including 220 with documented CAD and 492 healthy subjects. TaqMan assays were performed to genotype rs7412 and rs429358, the two variants that determine the APOE alleles ε2, ε3 and ε4. The association between APOE genotype and the lipid profile was analysed by comparing ε2 carriers, ε3 homozygotes and ε4 carriers.

RESULTS

The frequencies of ε2, ε3 and ε4 in the overall sample were 8%, 70% and 22%, respectively. CAD was not associated with APOE polymorphism. The total cholesterol level was higher in ε4 carriers compared with ε2 carriers: 5.07 vs 4.59 mmol/L (P = 0.016). The LDL-cholesterol level was lower in APOE ε2 carriers compared with ε3 homozygotes and ε4 carriers: 2.65 vs 3.03 and 3.17 mmol/L, respectively (p = 0.002). The total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios were similar in the three allelic groups. APOE polymorphism was not associated with diabetes, hypertension, waist circumference or body mass index.

CONCLUSIONS

Our results indicate that APOE gene polymorphism is associated with the lipid profile but not with CAD in Afro-Caribbean people. This lack of association with CAD may be explained by the low atherogenic profile observed in ε4 carriers, which may warrant further investigation.

Associations between explorative dietary patterns and serum lipid levels and their interactions with ApoA5 and ApoE haplotype in patients with recently diagnosed type 2 diabetes

Aims

In patients with type 2 diabetes (T2D), responsiveness of serum lipid concentrations to dietary patterns may vary by genotype. The aims of the present study were to identify explorative dietary patterns and to examine their independent associations with serum lipid levels and interactions with apolipoprotein (Apo)A5 and ApoE variants among patients recently diagnosed with T2D.

Methods

Within a cross-sectional analysis, participants of the German Diabetes Study (n = 348) with mean T2D duration of 6 months were investigated for fasting serum lipid levels, ApoA5 and ApoE genotypes; food consumption frequencies were assessed by a food propensity questionnaire. Dietary patterns were derived using principal component analysis (PCA) and reduced rank regression (RRR), which extracts patterns explaining variation in serum lipid concentrations.

Results

PCA yielded interpretable dietary patterns which were, however, not related to serum lipid levels. Relevance of the RRR patterns varied by genotype: a preferred consumption of fruit gum, fruit juice, and potato dumpling, whilst avoiding fruits and vegetables independently associated with higher triglyceride levels among ApoA5*2. Patients in the highest compared to the lowest tertile of pattern adherence had 99 % higher triglycerides. Lower consumption frequencies of butter, cream cake, French fries, or high-percentage alcoholic beverages were independently related to lower LDL-cholesterol among ApoE2 carriers, with those in the highest compared to the lowest tertile of pattern adherence having 40 % lower LDL-cholesterol (both P_interaction < 0.05).

Conclusions

Our explorative data analyses suggest that associations of dietary patterns with triglycerides and LDL-cholesterol differ by ApoA5 and ApoE haplotype in recently diagnosed T2D.

Trial registration Clinicaltrials.gov: NCT01055093. Date of registration: January 22, 2010 (retrospectively registered). Date of enrolment of first participant to the trial: September 2005

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0455-9) contains supplementary material, which is available to authorized users.

Insulin resistance, dyslipidemia, and apolipoprotein E interactions as mechanisms in cognitive impairment and Alzheimer's disease

An increased risk for Alzheimer's disease is associated with dyslipidemia and insulin resistance. A separate literature shows the genetic risk for developing Alzheimer's disease is strongly correlated to the presence of the E4 isoform of the apolipoprotein E carrier protein. Understanding how apolipoprotein E carrier protein, lipids, amyloid β peptides, glucose, central nervous system insulin, and peripheral insulin interact with one another in Alzheimer's disease is an area of increasing interest. Here, we will review the evidence relating apolipoprotein E carrier protein, lipids, and insulin action to Alzheimer's disease and Aβ peptides and then propose mechanisms as to how these factors might interact with one another to impair cognition and promote Alzheimer's disease.

Differential Effects of Meal Challenges on Cognition, Metabolism, and Biomarkers for Apolipoprotein E ɛ4 Carriers and Adults with Mild Cognitive Impairment

BACKGROUND

High intake of saturated fat (SF) and glycemic index (GI) foods is a risk factor for sporadic Alzheimer's disease. Meal challenges may elucidate mechanisms that contribute to this risk, enabling development of targeted interventions.

OBJECTIVE

To assess cognitive and metabolic changes after a meal high in SF and GI calories (HIGH) versus a meal low in these macronutrients (LOW) in older adults with and without cognitive impairment, and with and without the apolipoprotein E4 risk factor.

METHODS

46 adults with either cognitive impairment (CI) or normal cognition (NC) ingested a LOW (25% total fat, 7% SF, GI <55) and a HIGH meal (50% total fat, 25% SF, GI >70) in a blinded random fashion. Participants then underwent cognitive testing and blood sampling for metabolic and Alzheimer's disease biomarkers. Data were analyzed using repeated measures ANOVA and Spearman correlations.

RESULTS

E4-adults with NC demonstrated lower delayed memory scores after the HIGH compared to the LOW meal, whereas normal E4+ and CI E4- groups had higher scores after the HIGH meal (ANOVA p = 0.03). These findings were associated with meal-induced changes in glucose (p = 0.05), insulin (p = 0.004), triglycerides (p <  0.01), and plasma Aβ42 (p = 0.05).

CONCLUSIONS

These preliminary data suggest that cognitive performance of adults without CI may worsen following high SF and sugar meals, whereas adults with CI or those at risk for CI due to E4 status may benefit acutely from such meals. Furthermore, plasma Aβ was affected by meal type, suggesting a relationship between metabolic response and amyloid regulation.

Interactions between genetic variants and dietary lipid composition: effects on circulating LDL cholesterol in children

BACKGROUND

Elevated serum low-density lipoprotein (LDL) cholesterol is a predictor of cardiovascular disease events, and the quality of dietary fat is known to influence serum concentrations of LDL cholesterol in children. Interindividual differences in response to diet exist, but the underlying genetic factors remain largely unknown.

OBJECTIVE

We aimed to identify genetic variants that modify the variation in serum lipid response to dietary fat quality.

DESIGN

We used data from 2 longitudinal Finnish cohorts designed to study risk factors for cardiovascular diseases. Large-scale genotyping was performed with Metabochip in a long-term randomized controlled dietary intervention trial, the Special Turku Coronary Risk Factor Intervention Project (STRIP), for discovery of genetic polymorphisms. The observational Cardiovascular Risk in Young Finns Study (YFS) with genome-wide genetic data was used as a replication sample for the initial findings. Dietary records were used to calculate the ratio of unsaturated to saturated fats. Interaction models and multiple follow-ups were used in the analysis.

RESULTS

In the STRIP cohort, a variant within the PARK2 locus, rs9364628, showed moderate interaction with dietary fat quality and a consistent direction of effect in both scans on serum LDL-cholesterol concentration in children aged 5 and 7 y (P < 0.0084 and P < 0.0057, respectively). In the YFS cohort, we were unable to replicate the initial discovery signal, but rs12207186 within the PARK2 locus and dietary lipid quality had a stronger interaction effect on serum LDL-cholesterol concentration (P < 9.44 × 10(-5)) than did rs9364628 in children aged 6 y.

CONCLUSION

This genotyping study involving 2 cohorts of healthy Finnish children indicates a possible interaction between PARK2 variants and dietary fat quality on serum LDL-cholesterol concentration. This trial was registered at clinicaltrials.gov as NCT00223600.

Saturated and trans fats and dementia: a systematic review

Cognitive disorders of later life are potentially devastating. To estimate the relationship between saturated and trans fat intake and risk of cognitive disorders. PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for studies reporting saturated or trans fat intake and incident dementia, Alzheimer's disease (AD), or mild cognitive impairment (MCI) or cognitive decline. Only observational studies met the inclusion criteria: 4 for AD or other dementias, 4 for MCI, and 4 for cognitive decline. Saturated fat intake was positively associated with AD risk in 3 of 4 studies, whereas the fourth suggested an inverse relationship. Saturated fat intake was also positively associated with total dementia in 1 of 2 studies, with MCI in 1 of 4 studies, and with cognitive decline in 2 of 4 studies. Relationships between trans fat intake and dementia were examined in 3 reports with mixed results. Several, although not all, prospective studies indicate relationships between saturated and trans fat intake and risk of cognitive disorders.

Quantifying diet for nutrigenomic studies

The field of nutrigenomics shows tremendous promise for improved understanding of the effects of dietary intake on health. The knowledge that metabolic pathways may be altered in individuals with genetic variants in the presence of certain dietary exposures offers great potential for personalized nutrition advice. However, although considerable resources have gone into improving technology for measurement of the genome and biological systems, dietary intake assessment remains inadequate. Each of the methods currently used has limitations that may be exaggerated in the context of gene × nutrient interaction in large multiethnic studies. Because of the specificity of most gene × nutrient interactions, valid data are needed for nutrient intakes at the individual level. Most statistical adjustment efforts are designed to improve estimates of nutrient intake distributions in populations and are unlikely to solve this problem. An improved method of direct measurement of individual usual dietary intake that is unbiased across populations is urgently needed.

Continuous positive airway pressure reduces postprandial lipidemia in obstructive sleep apnea: a randomized, placebo-controlled crossover trial

RATIONALE

Dyslipidemia is common in Obstructive Sleep Apnea (OSA). Postprandial lipidemia (PPL) is a strong marker of cardiovascular risk. Evidence that OSA treatment improves PPL is lacking.

OBJECTIVES

To investigate the effect of continuous positive airway pressure (CPAP) treatment on postprandial lipidemia (PPL) in patients with obstructive sleep apnea (OSA) in the upper moderate or severe range.

METHODS

In this randomized, placebo-controlled crossover trial, we compared the effects of 2 months each of therapeutic and placebo CPAP on PPL.

MEASUREMENTS AND MAIN RESULTS

PPL was determined from the area under the 24-hour triglyceride concentration curve (TAG-AUC(24)) using seven blood samples drawn across both the wake and sleep periods. Secondary outcomes were the difference in other 24-hour lipid profiles. Thirty-eight eligible patients were randomly assigned to a treatment order and 29 patients completed the trial. CPAP reduced PPL compared with placebo with a mean TAG-AUC(24) difference of -357 mmol/L/d (95% confidence interval [CI], -687.3 to -26.8; P = 0.035). During both the CPAP and placebo studies, TAG levels peaked during both wakefulness (2:00 p.m.) and sleep (3:00 a.m.). Both peaks were lower during CPAP than placebo: 2:00 p.m., -0.49 mmol/L (95% CI, -0.74 to -0.24; P < 0.0005) and 3:00 a.m., -0.40 mmol/L (95% CI, -0.65 to -0.15; P = 0.002). Moreover, mean 24-hour total cholesterol was -0.19 mmol/L lower on CPAP (95% CI, -0.27 to -0.11; P < 0.00001).

CONCLUSIONS

This randomized trial demonstrated that treatment of severe OSA with CPAP improves postprandial TAG and total cholesterol levels. These effects may reduce the risk for cardiovascular events. The results imply that the association between OSA and cardiovascular disease may, in part, be caused by direct effects on dyslipidemia. Clinical trial registered with the Australian and New Zealand Clinical Trials Registry at www.anzctr.org.au (ACTRN 12605000066684).

E2 allele of the apolipoprotein E gene polymorphism is predictive for obesity status in Roma minority population of Croatia

Background and Aims

The Roma (Gypsies) are a transnational minority, founder population characterized by unique genetic background modeled by culturally determined endogamy. The present study explores whether the widely found cardiovascular diseases (CVD) risk effects of ACE I/D, APOE (ε2, ε3, ε4), eNOS-VNTR and LEP G2548A polymorphisms can be replicated in this specific population.

Methods and Results

The community-based study was carried on 208 adult Bayash Roma living in rural settlements of eastern and northern Croatia. Risk effect of four CVD candidate polymorphisms are related to the most prominent classical CVD risk phenotypes: obesity indicators (body mass index and waist circumference), hypertension and hyperlipidemia (triglycerides, HDL and LDL cholesterol). For all of them the standard risk cut-offs were applied. The extent to which the phenotypic status is related to genotype was assessed by logistic regression analysis. The strongest associations were found for ε2 allele of the APOE as a predictor of waist circumference (OR 3.301; 95%CI 1.254-8.688; p = 0.016) as well as for BMI (OR 3.547; 95%CI 1.471-8.557; p = 0.005). It is notable that ε3 allele of APOE gene turned out to be a protective genetic factor determining low lipid levels.

Conclusion

The strength of the relation and the similarity of the results obtained for both tested indicators of obesity provide firm evidence that APOE plays an important role in obesity development in the Roma population.

The vascular contribution to Alzheimer's disease

AD (Alzheimer's disease) is a progressive neurodegenerative disease of unknown origin. Despite questions as to the underlying cause(s) of this disease, shared risk factors for both AD and atherosclerotic cardiovascular disease indicate that vascular mechanisms may critically contribute to the development and progression of both AD and atherosclerosis. An increased risk of developing AD is linked to the presence of the apoE4 (apolipoprotein E4) allele, which is also strongly associated with increased risk of developing atherosclerotic cardiovascular disease. Recent studies also indicate that cardiovascular risk factors, including elevated blood cholesterol and triacylglycerol (triglyceride), increase the likelihood of AD and vascular dementia. Lipids and lipoproteins in the circulation interact intimately with the cerebrovasculature, and may have important effects on its constituent brain microvascular endothelial cells and the adjoining astrocytes, which are components of the neurovascular unit. The present review will examine the potential mechanisms for understanding the contributions of vascular factors, including lipids, lipoproteins and cerebrovascular Abeta (amyloid beta), to AD, and suggest therapeutic strategies for the attenuation of this devastating disease process. Specifically, we will focus on the actions of apoE, TGRLs (triacylglycerol-rich lipoproteins) and TGRL lipolysis products on injury of the neurovascular unit and increases in blood-brain barrier permeability.

Dietary fatty acids in dementia and predementia syndromes: epidemiological evidence and possible underlying mechanisms

Drugs currently used in the treatment of cognitive impairment and dementia have a very limited therapeutic value, suggesting the necessity to potentially individualize new strategies able to prevent and to slow down the progression of predementia and dementia syndromes. An increasing body of epidemiological evidence suggested that elevated saturated fatty acids (SFA) could have negative effects on age-related cognitive decline (ARCD) and mild cognitive impairment (MCI). Furthermore, a clear reduction of risk for cognitive decline has been found in population samples with elevated fish consumption, high intake of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), particularly n-3 PUFA. Epidemiological findings demonstrated that high PUFA intake appeared to have borderline non-significant trend for a protective effect against the development of MCI. Several hypotheses could explain the association between dietary unsaturated fatty acids and cognitive functioning, including mechanisms through the co-presence of antioxidant compounds in food groups rich in fatty acids, via atherosclerosis and thrombosis, inflammation, accumulation of b-amyloid, or via an effect in maintaining the structural integrity of neuronal membranes, determining the fluidity of synaptosomal membranes that thereby regulate neuronal transmission. However, recent findings from clinical trials with n-3 PUFA supplementation showed efficacy on depressive symptoms only in non-apolipoprotein E (APOE) epsilon4 carriers, and on cognitive symptoms only in very mild Alzheimer's disease (AD) subgroups, MCI patients, and cognitively unimpaired subjects non-APOE epsilon4 carriers. These data together with epidemiological evidence support a possible role of fatty acid intake in maintaining adequate cognitive functioning and possibly for the prevention and management of cognitive decline and dementia, but not when the AD process has already taken over.

Genotype-phenotype associations: modulation by diet and obesity

Changes in diet are likely to reduce chronic disorders, but after decades of active research and heated discussion, the question still remains: what is the optimal diet to achieve this elusive goal? Is it a low-fat diet, as traditionally recommended by multiple medical societies? Or a high monounsaturated fat (MUFA) diet as predicated by the Mediterranean diet? Perhaps a high polyunsaturated fat (PUFA) diet based on the cholesterol-lowering effects? The right answer may be all of the above but not for everybody. A well-known phenomenon in nutrition research and practice is the dramatic variability in interindividual response to any type of dietary intervention. There are many other factors influencing response, and they include, among many others, age, sex, physical activity, alcohol, and smoking as well as genetic factors that will help to identify vulnerable populations/individuals that will benefit from a variety of more personalized and mechanistic-based dietary recommendations. This potential could and needs to be developed within the context of nutritional genomics that in conjunction with systems biology may provide the tools to achieve the holy grail of dietary prevention and therapy of chronic diseases and cancer. This approach will break with the traditional public health approach of "one size fits all." The current evidence based on nutrigenetics has begun to identify subgroups of individuals who benefit more from a low-fat diet, whereas others appear to benefit more from high MUFA or PUFA diets. The continuous progress in nutrigenomics will allow some time in the future to provide targeted gene-based dietary advice.

Fat intake at midlife and cognitive impairment later in life: a population-based CAIDE study

OBJECTIVE

To investigate the association of midlife dietary fat intake to cognitive performance, and to the occurrence of clinical mild cognitive impairment (MCI) later in life in a non-demented population.

DESIGN

A longitudinal population-based study.

SETTING

Populations of Kuopio and Joensuu, Eastern Finland.

PARTICIPANTS AND METHODS

Participants of the CAIDE study were derived from random, population-based samples studied at midlife (1972, 1977, 1982 or 1987). After an average follow-up of 21 years, a total of 1449 (72%) individuals aged 65-80 years participated in the re-examination in 1998. Altogether 82 (5.7%) people were diagnosed as having MCI. Dietary information was collected with a structured questionnaire and an interview at midlife.

MAIN OUTCOME MEASURES

MCI, global cognitive and executive functions, episodic, semantic and prospective memory and psychomotor speed.

RESULTS

Abundant saturated fat (SFA) intake from milk products and spreads at midlife was associated with poorer global cognitive function and prospective memory and with an increased risk of MCI (OR 2.36, 95% CI 1.17-4.74) after adjusting for demographic and vascular factors, other fats and ApoE. On the contrary, high intake of polyunsaturated fatty acids (PUFA) was associated with better semantic memory. Also frequent fish consumption was associated with better global cognitive function and semantic memory. Further, higher PUFA-SFA ratio was associated with better psychomotor speed and executive function.

CONCLUSIONS

Our data suggests that dietary fat intake at midlife affects cognitive performance and occurrence of MCI later in life. The impact of dietary interventions needs to be tested in clinical trials.

The relationship of sterol regulatory element-binding protein cleavage-activation protein and apolipoprotein E gene polymorphisms with metabolic changes during weight reduction

Sterol regulatory element-binding protein cleavage-activating protein (SCAP) and apolipoprotein E (apo E) regulate cellular and plasma lipid metabolism. Therefore, variations in the corresponding genes might influence weight reduction and obesity-associated metabolic changes. We investigated the relationships of SCAP (Ile796Val) and apo E polymorphisms on metabolic changes during weight reduction by using a 12-week very low-energy diet. Body composition, serum lipids, plasma glucose, and insulin were assessed in 78 healthy premenopausal women (initial body mass index, 34 +/- 4 kg/m(2); age, 40 +/- 4 years) before and after the intervention. The SCAP genotype groups did not differ in the responses of any parameters measured during weight reduction. Apo E did not differentiate the weight loss, but the changes in total and low-density lipoprotein cholesterol for the genotype groups apo E epsilon2/3, epsilon3/3, as well as epsilon3/4 and epsilon4/4 combined were -0.94 +/- 0.56 and -0.59 +/- 0.32, -0.71 +/- 0.49 and -0.49 +/- 0.45, and -0.55 +/- 0.47 and -0.37 +/- 0.39 mmol/L, respectively (P < .05 for both). In conclusion, neither the SCAP Ile796Val nor the apo E polymorphism was associated with weight loss in obese premenopausal women. However, the apo E-but not SCAP genotype-seems to be one of the modifying factors for serum cholesterol concentrations during very low-energy diet in obese premenopausal women.

Apolipoprotein E genotype affects the response to lipid-lowering therapy in Chinese patients with type 2 diabetes mellitus

OBJECTIVE

To evaluate the effect of apolipoprotein E (apoE) genotype on baseline lipid levels and the response to hydroxy-methyl glutaryl coenzyme A reductase inhibitors (statins) therapy in Chinese patients with type 2 diabetes mellitus (DM).

RESEARCH DESIGN AND METHODS

We consecutively recruited Chinese patients with type 2 DM requiring lipid-lowering therapy according to current guidelines. Patients were started on either simvastatin 10 mg daily or given an equivalent dose of lovastatin 20 mg. After 12 weeks of statin therapy, patients had fasting lipid profiles repeated. ApoE genotyping was performed by restriction fragment length polymorphism (RFLP).

RESULTS

Ninety-six patients were studied. The epsilon3/epsilon3 genotype was in 62.5%, epsilon2/epsilon3 and epsilon3/epsilon4, 16.7 and 20.8%, respectively. After adjusting for confounding variables, baseline total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels were significantly higher in those with epsilon3/epsilon4 compared with epsilon2/epsilon3 genotype (6.7 vs. 5.5 mm for TC, 4.5 vs. 3.6 mm for LDL-C; p = 0.015 and p = 0.025, respectively). With statin therapy, epsilon3/epsilon4 patients had significantly greater LDL-C lowering compared with epsilon2/epsilon3 patients (48 vs. 27.7%; p = 0.04). There was no gender difference in baseline lipid parameters or response to statin therapy.

CONCLUSIONS

ApoE genotype accounts for interindividual variability of baseline cholesterol levels, and response to statin therapy in Chinese patients with type 2 DM.

Influencia de los factores genéticos y ambientales en el metabolismo lipídico y riesgo cardiovascular asociado al gen apoE

The apolipoprotein E (ApoE) plays an important role in lipid metabolism. This apoprotein presents three major isoforms (apoE2, apoE3 and apoE4) that modulate lipid levels. Carriers of the apoE4 allele have higher total and LDL-cholesterol plasma concentration and a greater coronary risk, particularly for myocardial infarction. Nevertheless, not all the people with this allele develop the disease, which suggests that other genetic or environmental factors are necessary for its total expression. In this review, we will analyze the importance of several polymorphisms in the apoE gene promoter region, as well as various environmental factors, including diet, in the association of this gene with lipid metabolism and cardiovascular risk.

Baseline plasma C-reactive protein concentrations influence lipid and lipoprotein responses to low-fat and high monounsaturated fatty acid diets in healthy men

To date, no studies have compared the effects of consuming a low-fat diet and a high monounsaturated fatty acid (MUFA) diet, under unrestricted energy intake conditions, on plasma C-reactive protein (CRP) concentrations. Men [n = 61; 37.5 +/- 11.5 y old (mean +/- SD), mean BMI 29.0 +/- 5.0 kg/m2] were randomly assigned to consume ad libitum a moderately low-fat diet (25.8% of energy intake from fat) or a high-fat diet rich in MUFA (40.1% of energy intake from fat, 22.5% from MUFA) for 6-7 wk. Plasma CRP concentrations were measured using a highly sensitive assay. Neither diet affected the plasma CRP concentration. However, baseline CRP concentrations predicted lipoprotein/lipid responsiveness to the experimental diets. After intake of the low-fat diet, plasma total and VLDL-triglyceride (TG) concentrations were increased in the subgroup with high CRP concentrations (P < 0.05 and P < 0.01, respectively) whereas they were reduced in the subgroup with low CRP concentrations at baseline (P < 0.01 for both). The high-MUFA diet reduced plasma TG, VLDL-TG, and VLDL cholesterol only in the subgroup with low CRP at baseline (P < 0.0001). In conclusion, the low-fat diet and the high-MUFA diet did not affect plasma CRP concentrations. However, baseline plasma CRP concentrations may modulate the diet-induced changes in plasma lipid and lipoprotein concentrations.

Nutritional genomics

Nutritional genomics has tremendous potential to change the future of dietary guidelines and personal recommendations. Nutrigenetics will provide the basis for personalized dietary recommendations based on the individual's genetic make up. This approach has been used for decades for certain monogenic diseases; however, the challenge is to implement a similar concept for common multifactorial disorders and to develop tools to detect genetic predisposition and to prevent common disorders decades before their manifestation. The preliminary results involving gene-diet interactions for cardiovascular diseases and cancer are promising, but mostly inconclusive. Success in this area will require the integration of different disciplines and investigators working on large population studies designed to adequately investigate gene-environment interactions. Despite the current difficulties, preliminary evidence strongly suggests that the concept should work and that we will be able to harness the information contained in our genomes to achieve successful aging using behavioral changes; nutrition will be the cornerstone of this endeavor.

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

BACKGROUND

The apolipoprotein E (APOE) gene promoter polymorphism (-219G-->T) has been associated with increased risk of myocardial infarction, premature coronary artery disease, and decreased plasma apolipoprotein E concentrations.

OBJECTIVE

We aimed to determine in healthy subjects whether this polymorphism modifies the susceptibility of LDL to oxidation and the lipid response to the content and quality of dietary fat.

DESIGN

Fifty-five healthy men with the APOE3/E3 genotype (7 GG, 38 GT, and 10 TT) completed 3 dietary periods, each lasting 4 wk. The first was a saturated fatty acid (SFA)-rich diet [38% fat-20% SFA and 12% monounsaturated fatty acid (MUFA)-and 47% carbohydrates (CHO)], which was followed by a CHO-rich diet (30% fat-<10% SFA and 12% MUFA-and 55% CHO) or a MUFA-rich diet (38% fat-<10% SFA and 22% MUFA-and 47% CHO) in a randomized crossover design. At the end of each dietary period, LDL oxidation susceptibility, lipids, and lipoproteins were measured.

RESULTS

Compared with carriers of the G allele, TT subjects had a significantly (P < 0.05) shorter lag time after the SFA diet. The replacement of the SFA diet by the CHO or MUFA diet induced a greater increase (P < 0.05) in lag time in the TT subjects than in the GG or GT subjects. Carriers of the T allele had higher LDL-cholesterol (P < 0.05) and apolipoprotein B (P < 0.05) plasma concentrations after the SFA diet than did GG subjects. Compared with GG subjects, carriers of the T allele had a significantly (P < 0.05) greater decrease in LDL cholesterol and apolipoprotein B when they changed from the SFA to the CHO diet.

CONCLUSION

The -219G-->T polymorphism may partially explain differences in individual responses to diet.

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

LDL particle size is dependent on both genetic factors and environmental factors such as dietary fat composition. The apolipoprotein E (apoE) genotype is a major genetic determinant of LDL size. Thus, the aim of this work was to study whether the apoE genotype interacts with the quantity and quality of dietary fat, modifying LDL size in young healthy subjects. Healthy subjects (n = 84; 66 apoE 3/3, 8 apoE 4/3, 10 apoE 3/2) were subjected to 3 dietary periods, each lasting 4 wk. The first was an SFA-enriched diet (38% fat, 20% SFA), which was followed by a carbohydrate (CHO)-rich diet (30% fat, < 10% SFA, 55% carbohydrate) or a monounsaturated fatty acid (MUFA) olive oil-rich diet (38% fat, 22% MUFA) following a randomized crossover design. At the end of each diet period, LDL particle size and plasma levels of total cholesterol, LDL cholesterol (LDL-C), HDL-C, apoB, apoA-I, and triacylglycerols were determined. LDL particle size was significantly higher (P < 0.04) in subjects with the apoE 4/3 genotype compared with those with apoE 3/3 and apoE 3/2 in the basal state. LDL size was smaller (P < 0.02) after the CHO diet than after the MUFA or SFA diets. After the CHO diet, a significant increase in LDL particle size (P < 0.035) was noted with respect to the MUFA diet in apoE 4/3 subjects, whereas a significant decrease was observed in the apoE 3/3 individuals (P < 0.043). In conclusion, a Mediterranean diet, high in MUFA-fat increases LDL particle size compared with a CHO diet, and this effect is dependent of apoE genotypes.

Obesity and alcohol modulate the effect of apolipoprotein E polymorphism on lipids and insulin

OBJECTIVE

To assess the interaction between apolipoprotein (apo) E polymorphism, alcohol consumption, and BMI on insulin, lipid, and lipoprotein levels in men.

RESEARCH METHODS AND PROCEDURES

Cross-sectional study of 266 healthy men without hypolipidemic or antidiabetic drug treatment. BMI, apo E polymorphisms, insulin, and lipid and lipoprotein levels were assessed. Alcohol consumption was assessed by questionnaire. epsilon2/epsilon4 carriers were excluded from the analysis.

RESULTS

On bivariate analysis, epsilon2 carriers had lower levels of total and low-density lipoprotein cholesterol and higher levels of apo E and lipoparticle B:E than epsilon3 carriers, the opposite being found for epsilon4 carriers compared with epsilon3 carriers; epsilon4 carriers also had significantly higher insulin levels. On multivariate analysis, significant interactions (p < 0.04) between apo E alleles and increased BMI were found for total and low-density lipoprotein cholesterol and insulin levels, the increase in those parameters with BMI being stronger among epsilon4 carriers than among epsilon3 or epsilon2 carriers. Significant interactions (p < 0.02) between apo E alleles and alcohol consumption were also found for apo B levels, which increased in epsilon2 carriers but remained relatively stable in epsilon3 and tended to decrease in epsilon4 carriers.

DISCUSSION

These data suggest that effects of apo E alleles on lipids and insulin levels are partly dependent on environmental variables such as BMI and alcohol intake. These findings highlight the importance of gene x environment interactions on the deleterious effect of obesity on cardiovascular risk factors.

Genes, diet and serum lipid concentrations: lessons from ethnically diverse populations and their relevance to coronary heart disease in Asia

PURPOSE OF REVIEW

The burden of coronary heart disease (CHD) in Asia has risen in tandem with socio-economic development and urbanization. Although all ethnic groups have been affected, some appear to be at particularly high risk. The basis of these ethnic differences remains poorly understood.

RECENT FINDINGS

Differing levels of risk factors for CHD have been observed between ethnic groups. Previous studies, however, may be confounded by a large ethnic variation in socio-economic status and place of residence. Few studies have taken dietary factors into account. Recent studies involving Chinese, Malays and Asian Indians living in Singapore suggest that neither dietary nor genetic factors, taken in isolation, sufficiently explain ethnic differences in serum lipid profiles. Several genetic variants in key candidate genes (apolipoprotein E, APOE, cholesteryl ester transfer protein, CETP and hepatic lipase, LIPC) have recently been found to modulate the association between dietary factors and serum lipid concentrations in these ethnic groups and in other populations.

SUMMARY

To fully evaluate the differences in CHD risk between ethnic groups, environmental exposures, including dietary factors need to be carefully evaluated, and gene-environment interactions that may give rise to these differences need to be taken into account. These are critical steps in the development of targeted strategies to contain the epidemic of coronary heart disease in Asia. An understanding of the basis of these differences may also provide insights into the pathogenesis of disease that one cannot get through the examination of more homogenous populations.

Influences of apolipoprotein E polymorphism on the response of plasma lipids to the ad libitum consumption of a high-carbohydrate diet compared with a high-monounsaturated fatty acid diet

The purpose of this study was to assess the contribution of the apolipoprotein E (apoE) polymorphism and factors, such as age and waist circumference, to variations in plasma low-density lipoprotein-cholesterol (LDL-C) response following ad libitum consumption of a diet rich in complex carbohydrates (high-CHO: 58% of energy as CHO) versus a diet rich in fat and monounsaturated fatty acids (high-MUFA: fat, 40% of energy and 22% as MUFA). Sixty-five men participated in this parallel 6- to 7-week study involving either a high-CHO or a high-MUFA diet. Fasting plasma lipid profile and anthropometry were determined at the beginning and at the end of the dietary period. The high-CHO and high-MUFA diets both induced significant (P<.01) and comparable reductions in body weight and waist circumference. These changes were associated with a significant (P<.01) and comparable decrease in LDL-C (-19% and -16%, respectively). Stepwise multiple regression analyses showed that 32% of the variation in the LDL-C response to the high-CHO diet was attributable to the apoE polymorphism (18.5%, P=.04) and waist circumference (13.5%, P=.03) indicating that men with a waist circumference greater than 100 cm and the E2 allele had the greatest reduction in plasma LDL-C after the high-CHO diet. On the other hand, in the high-MUFA group, waist circumference was the only significant contributing factor to the LDL-C response and accounted for 44.5% of its variance. In conclusion, the plasma LDL-C response to ad libitum comsumption of a high-CHO and a high-MUFA diets are not modulated to the same extent by the apoE polymorphism and waist circumference.

APOE polymorphism and lipid profile in three ethnic groups in the Singapore population

BACKGROUND

Serum lipid concentrations are modulated by environmental factors such as exercise, alcohol intake, smoking, obesity and dietary intake and genetic factors. Polymorphisms at the Apolipoprotein E (APOE) locus have consistently shown a significant association with total and LDL-cholesterol (LDL-C). However, their impact on HDL-cholesterol (HDL-C) may be population dependent. Having three major ethnic groups within a similar social environment allows us to study the role of genetics and their interactions with lifestyle factors on the serum lipid profile and coronary risk in Asians.

METHODS

This study included 1740 males (1146 Chinese, 327 Malays and 267 Asian Indians) and 1950 females (1329 Chinese, 360 Malays and 261 Asian Indians) with complete data on anthropometric indices, fasting lipids, smoking status, alcohol consumption, exercise frequency and genotype at the APOE locus.

RESULTS

Malays and Asian Indians were more obese compared with the Chinese. Smoking was uncommon in all females but Malay males had significantly higher prevalence of smokers. Malays had the highest LDL-C whilst Indians had the lowest HDL-C, The epsilon 3 allele was the most frequent allele in all three ethnic groups. Malays had the highest frequency of epsilon 4 (0.180 and 0.152) compared with Chinese (0.085 and 0.087) and Indians (0.108 and 0.075) in males and females, respectively. The epsilon 2 allele was the least common in Asian Indians. Total cholesterol (TC) and LDL-C was highest in epsilon 4 carriers and lowest in epsilon 2 carriers. The reverse was seen in HDL-C with the highest levels seen in epsilon 2 subjects. The association between ethnic group and HDL-C differed according to APOE genotype and gender. Asian Indians had the lowest HDL-C for each APOE genotype except in Asian Indian males with epsilon 2, where HDL-C concentrations were intermediate between Chinese and Malays.

CONCLUSION

Ethnic differences in lipid profile could be explained in part by the higher prevalence of epsilon 4 in the Malays. Ethnicity may influence the association between APOE genotypes and HDL-C. APOE genotype showed no correlation with HDL-C in Malay males whereas the association in Asian Indians was particularly marked. Further studies of interactions between genes and environmental factors will contribute to the understanding of differences of coronary risk amongst ethnic groups.

Apolipoprotein E polymorphisms and mortality in Italian type 2 diabetic patients

AIMS

To determine if apolipoprotein E polymorphism is associated with cardiovascular or all-cause mortality in Italian Type 2 diabetic patients.

METHODS

A prospective study of mortality in Type 2 diabetic patients (n = 433) as a function of apolipoprotein E phenotype, which was assessed at entry into the study. During follow up (10 years), 110 (25.4%) patients died of which 66 (15.2%) were the result of cardiovascular causes. Cause of death was established from death certificates and clinical records. The clinical status of the survivors was determined at the end of the study.

RESULTS

Apolipoprotein E polymorphisms were not associated with excess cardiovascular or all-cause mortality in the Italian Type 2 diabetic patients either in univariate or multivariate analyses. Age, duration of diabetes and glycated haemoglobin levels at entry were the primary determinants of premature mortality in the diabetic population.

CONCLUSIONS

Apolipoprotein E polymorphisms are not markers for premature mortality in Italian Type 2 diabetic patients. The impact of apolipoprotein E mutations may be attenuated by environmental factors, notably a healthier diet, in Italian patients.

Apolipoprotein and apolipoprotein receptor genes, blood lipids and disease

PURPOSE OF REVIEW

Apolipoproteins and their receptors are the main controllers of lipid metabolism and, as such, have a major impact not only on the risk of cardiovascular disease but also on the development and degeneration of the central nervous system. Variations in the genes coding for these apolipoproteins and their receptors and the interaction with the environment determine individual susceptibility to metabolic disturbances, the response to dietary or pharmacological intervention and, finally, to disease.

RECENT FINDINGS

This review will focus on recent findings, such as the latest concepts regarding apolipoprotein E in neurodevelopment, the newly identified apolipoprotein A-V and its influence in triglyceride metabolism, and the improved understanding of apolipoprotein A-I and HDL metabolism in the light of the discovery of the ABC family of transporters. Other key aspects of lipoprotein metabolism and cardiovascular disease risk such as apolipoprotein B-100, the LDL receptor, apolipoprotein C-III or apolipoprotein (a) will be updated.

SUMMARY

Variations in these genes will be analysed in relation to plasma lipid levels, their interactions with diet, treatment or other environmental stimuli, and their influence on the risk of cardiovascular disease and neurological disorders.