Impact of REV-ERB alpha gene polymorphisms on obesity phenotypes in adult and adolescent samples.

BACKGROUND: REV-ERBα has been shown to regulate adipogenesis and lipid metabolism as well as to link the circadian timing system to whole body metabolic homeostasis. We thus tested whether polymorphisms in REV-ERBα could be associated with metabolic phenotypes in human population samples. METHODS: We analyzed the associations between 5 REV-ERBα polymorphisms and anthropometric (body weight, body mass index (BMI), waist and hip circumferences), biochemical (plasma lipid, glucose and insulin levels) and clinical (systolic and diastolic blood pressure) variables in three population-based studies (MONICA Lille n=1155 adults, MONA LISA Lille n=1170 adults and HELENA n=1155 adolescents). We assessed in vitro, the potential influence of one REV-ERBα polymorphism in transient transfection assays using two different cell lines. RESULTS: We observed significant and consistent associations between the T minor allele of the REV-ERBα rs2071427 polymorphism (located in intron 1) and higher BMI (mean allele effect=+0.33 kg m(-2)) in the MONICA Lille (P=0.02), MONA LISA (P=0.02) and HELENA (P=0.03) studies. The odds ratios for obesity associated with this allele were 1.67 (1.00-2.79) (P=0.05) in MONICA Lille, 1.29 (1.01-1.65) (P=0.04) in MONA LISA Lille and the odds ratio for overweight was 1.48 (1.08-2.03) (P=0.01) in HELENA. In transfection experiments in human hepatocyte-derived cell lines, the REV-ERBα intron 1 directed the transcription of a luciferase reporter gene independently of the rs2071427 polymorphism. CONCLUSION: Our results suggest that the REV-ERBα rs2071427 polymorphism modulates body fat mass in both adult and young people.

Thyroid hormone receptor alpha gene variants increase the risk of developing obesity and show gene-diet interactions.

OBJECTIVE: Thyroid hormone receptor-beta resistance has been associated with metabolic traits. THRA gene sequencing of an obese woman (index case) who presented as empirical thyroid hormone receptor-α (THRA) resistance, disclosed a polymorphism (rs12939700) in a critical region involved in TRα alternative processing. DESIGN AND SUBJECTS: THRA gene variants were evaluated in three independent europid populations (i) in two population cohorts at baseline (n=3417 and n=2265), 6 years later (n=2139) and (ii) in 4734 high cardiovascular risk subjects (HCVR, PREDIMED trial). RESULTS: The minor allele of the index case polymorphism (rs12939700), despite having a very low frequency (4%), was significantly associated with higher body mass index (BMI) (P=0.042) in HCVR subjects. A more frequent THRA polymorphism (rs1568400) was associated with higher BMI in subjects from the population (P=0.00008 and P=0.05) after adjusting for several confounders. Rs1568400 was also strongly associated with fasting triglycerides (P dominant=3.99 × 10(-5)). In the same sample, 6 years later, age and sex-adjusted risk of developing obesity was significantly increased in GG homozygotes (odds ratio 2.93 (95% confidence interval, 1.05-6.95)). In contrast, no association between rs1568400 and BMI was observed in HCVR subjects, in whom obesity was highly prevalent. This might be explained by the presence of an interaction (P <0.001) among the rs1568400 variant, BMI and saturated fat intake. Only when saturated fat intake was high (>24.5 g d(-1)), GG carriers showed a significantly higher BMI than A carriers after controlling for energy intake and physical activity. CONCLUSIONS: THRA gene polymorphisms are associated with obesity development. This is a novel observation linking the THRA locus to metabolic phenotypes.

Association between liver X receptor alpha gene polymorphisms and risk of metabolic syndrome in French populations.

CONTEXT: The metabolic syndrome is a complex and multifactorial disorder often associated with type 2 diabetes mellitus and cardiovascular diseases. The liver X receptor alpha (NR1H3) plays numerous roles in metabolic pathways involved in metabolic syndrome. OBJECTIVE: In the search for susceptibility genes to metabolic syndrome, we hypothesized that common genetic variation in NR1H3 gene influences metabolic syndrome susceptibility. DESIGN: Two large French population-based studies (n=1130 and 1160) including overall 664 individuals with and 1626 individuals without metabolic syndrome were genotyped for three polymorphisms (rs12221497, rs11039155 and rs2279239) of NR1H3. RESULTS: We found that the -6A allele of rs11039155 was consistently associated with a 30% reduction in risk of metabolic syndrome in the two independent population samples (adjusted OR (95% CI)=0.68 (0.53-0.86), P=0.001 for the combined sample). Moreover, it was associated with an increase in plasma HDL-cholesterol concentrations (P=0.02 for the combined sample). Neither rs12221497 nor rs11039155, both polymorphisms located in the 5' region of NR1H3, had significant influence on NR1H3 and ATP-binding cassette transporter A1 (ABCA1) gene expression in primary human macrophages. CONCLUSIONS: These results suggest that NR1H3 plays an important role in the HDL-cholesterol metabolism and in the genetic susceptibility to metabolic syndrome.

Unhealthy effects of atmospheric temperature and pressure on the occurrence of myocardial infarction and coronary deaths. A 10-year survey: the Lille-World Health Organization MONICA project (Monitoring trends and determinants in cardiovascular disease).

BACKGROUND: Associations between an increase in coronary heart disease occurrence and low atmospheric temperatures have been reported from mortality data and hospital admission registries. However, concomitant increases in noncardiovascular case fatality rates and selection bias of hospital cases may weaken this observation. In this study, we addressed the question of the relationships between fatal and nonfatal coronary diseases and meteorological variables in 10-year data (1985 to 1994) collected in a morbidity registry (Lille-WHO MONICA Project) monitoring 257 000 men from 25 to 64 years of age. METHODS AND RESULTS: The impacts of atmospheric temperature (in Celsius) and pressure (in millibars) on daily rates of myocardial infarction (MI) and coronary deaths were studied. Percentages of variation of event rates according to meteorological variations were derived from the relative risks estimated with a Poisson regression model. During the 10-year longitudinal survey, 3616 events occurred. Rates of events decreased linearly with increasing atmospheric temperature. For atmospheric pressure, we detected a V-shaped relationship, with a minimum of daily event rates at 1016 mbar. A 10 degrees C decrease was associated with a 13% increase in event rates (P<0.0001); a 10-mbar decrease <1016 mbar and a 10-mbar increase >1016 mbar were associated with a 12% increase (P=0.001) and an 11% increase (P=0. 01) in event rates, respectively. These effects were independent and influenced both coronary morbidity and mortality rates, with stronger effects in older age groups and for recurrent events. CONCLUSIONS: This longitudinal study is the first to estimate the attributable effect of meteorological variables on MI morbidity in population and strongly argues for a systematic fight against cold in cardiovascular disease prevention, particularly in older ages and after a first MI.

Association of 3'-UTR polymorphisms of the oxidised LDL receptor 1 (OLR1) gene with Alzheimer's disease.

Although possession of the epsilon 4 allele of the apolipoprotein E gene appears to be an important biological marker for Alzheimer's disease (AD) susceptibility, strong evidence indicates that at least one additional risk gene exists on chromosome 12. Here, we describe an association of the 3'-UTR +1073 C/T polymorphism of the OLR1 (oxidised LDL receptor 1) on chromosome 12 with AD in French sporadic (589 cases and 663 controls) and American familial (230 affected sibs and 143 unaffected sibs) populations. The age and sex adjusted odds ratio between the CC+CT genotypes versus the TT genotypes was 1.56 (p=0.001) in the French sample and 1.92 (p=0.02) in the American sample. Furthermore, we have discovered a new T/A polymorphism two bases upstream of the +1073 C/T polymorphism. This +1071 T/A polymorphism was not associated with the disease, although it may weakly modulate the impact of the +1073 C/T polymorphism. Using 3'-UTR sequence probes, we have observed specific DNA protein binding with nuclear proteins from lymphocyte, astrocytoma, and neuroblastoma cell lines, but not from the microglia cell line. This binding was modified by both the +1071 T/A and +1073 C/T polymorphisms. In addition, a trend was observed between the presence or absence of the +1073 C allele and the level of astrocytic activation in the brain of AD cases. However, Abeta(40), Abeta(42), Abeta total, and Tau loads or the level of microglial cell activation were not modulated by the 3'-UTR OLR1 polymorphisms. Finally, we assessed the impact of these polymorphisms on the level of OLR1 expression in lymphocytes from AD cases compared with controls. The OLR1 expression was significantly lower in AD cases bearing the CC and CT genotypes compared with controls with the same genotypes. In conclusion, our data suggest that genetic variation in the OLR1 gene may modify the risk of AD.

Omega-3 index levels and associated factors in a middle-aged French population: the MONA LISA-NUT Study.

BACKGROUND/OBJECTIVES: The omega-3 index (the summed percentage content of eicosapentaenoic and docosahexaenoic acids in red blood cells) is associated with a lower risk of fatal coronary heart disease and sudden cardiac death. We aimed to determine which socio-demographic, behavioural or clinical factors are independently associated with the omega-3 index and the extent to which seafood consumption mediates the index's association with socio-economic status (SES). SUBJECTS/METHODS: As part of the cross-sectional MONA LISA-NUT survey (2005-2007), gas chromatography was used to analyse the red blood cell fatty acid composition in 503 French subjects aged 35-64 years. Dietary data were collected by trained dieticians via a validated food frequency questionnaire and a prospective 3-day food record. Risk factors were estimated with standardised measurements and questionnaires. SES was assessed through the self-reported educational and income tax levels. RESULTS: The mean ± s.d. omega-3 index was 6.02 ± 1.75%. In the best parsimonious predictive model (which explained 32% of the variability in the omega-3 index), age, educational level and seafood servings were significantly and positively associated with the index. In contrast, waist circumference and smoking were inversely associated with the index. In a mediation analysis that took account of all these factors, seafood servings explained about 40% of the association between educational level and the omega-3 index. Similar results were obtained for the income tax level. CONCLUSIONS: The inverse association between SES and omega-3 index is largely explained (40%) by an insufficient seafood intake. It remains to be seen which other factors mediate this association.

VLDL receptor polymorphism, cognitive impairment, and dementia.

OBJECTIVE: Clinical, epidemiologic, and pathologic observations suggest that vascular risk factors are associated with impaired cognition. Previous studies supported an association between cognitive decline and APOE. Although the underlying mechanism is not clear, it might involve apoE receptors, such as the very low density lipoprotein receptor. METHODS: The impact of a polymorphic triplet repeat in the very low density lipoprotein receptor gene (VLDLR) on cognitive function was examined in two independent studies: a population study involving 221 demented subjects compared with 249 control subjects and a clinical study involving 124 demented subjects compared with 179 control subjects. RESULTS: In the population study, the presence of the VLDLR-5-repeat allele was associated with a relative risk of dementia (OR, 1.9; 95% CI, 1.2 to 3.0). This result was confirmed in the clinical study (OR, 8.1; 95% CI, 4.4 to 15.1) and was more pronounced in subjects with mixed or vascular dementia than in patients with AD. CONCLUSION: The VLDLR-5-repeat allele may constitute a genetic susceptibility factor for dementia, particularly in the presence of vascular risk factors. This observation suggests the influence of vascular risk factors in the occurrence of dementia.

Gender related association between genetic variations of APOC-III gene and lipid and lipoprotein variables in northern France.

The goal of the present study was to assess the impact of variability at the APOC-III insulin response element (APOC-III IRE) genetic locus on lipid, lipoprotein and complex lipoprotein particle levels as well as on the risk of dyslipidemia, in the population of northern France. To this end, 590 men and 579 women were randomly selected in the urban community of Lille in the framework of the MONICA project. Three polymorphisms, -482, -455 in the APOC-III insulin response element (IRE) and SstI in the 3'-noncoding region of the APOC-III gene locus were assessed. Compared to the most common alleles, the rare alleles of -482 and -455 were associated with increased levels of apoB-containing particles (LDL-cholesterol, apoB) and of triglyceride-related markers (apoC-III and LpC-III:B) in women, but not in men, suggesting a gender-related impact of APOC-III polymorphisms on these variables. Similarly, triglycerides, LpC-III:B and apoB were higher in women bearing the rare allele of SstI than in those with the most common allele. There was no evidence for any significant association between any of the -482, -455, and SstI alleles and lipid disorders (mixed hyperlipidemia, hypertriglyceridemia and hypercholesterolemia) in this sample of randomly selected men and women from northern France. In contrast, the prevalence of the haplotype that combined the rare alleles of the -482 and -455 sites was increased only in women with hypertriglyceridemia. Therefore, although the individual risk of hypertriglyceridemia is increased in women with the haplotype T, C at -482, -455, it appears that the -482, -455 and SstI APOC-III gene polymorphisms are not major contributors to the risk of dyslipidemia in the population of northern France.

Impact of sulfonylurea receptor 1 genetic variability on non-insulin-dependent diabetes mellitus prevalence and treatment: a population study.

The high affinity sulfonylurea receptor 1 (SUR1) is involved in the metabolism of glucose in pancreatic beta-cells. We investigated the impact of the SUR1 intron 16-3t-->c polymorphism on non-insulin-dependent diabetes mellitus (NIDDM) prevalence in a large representative sample of French men and women, 35-64 years old, and explored potential relationships between the SUR1 intron 16 -t-->c polymorphism and sulfonylurea therapy efficiency. This study took place in Lille (northern), Strasbourg (eastern), and Toulouse (southern France). One hundred and twenty-two subjects with NIDDM were registered. We stratified NIDDM subjects according to their medical treatment: sulfonylureas (n = 70) versus other treatments (n = 50). From the three populations, a control group was selected (n = 1,250). Subjects carrying the cc intron 16 genotype had an increased risk of NIDDM [odds ratio (OR) = 1.76, 95% confidence interval (CI) 1.10-2.80; P = 0.017]. Subjects bearing at least one -3c allele and treated with sulfonylurea agents had fasting plasma triglyceride concentrations 35% lower than subjects that were tt homozygous (P = 0.026), whereas no difference could be detected between genotypes in NIDDM subjects treated with other treatments. The SUR1 intron 16 -3t-->c polymorphism was associated with an increased susceptibility to NIDDM in this population study, and seems to modulate the sulfonylurea therapy efficiency on hypertriglyceridemia reduction. This observation may help to better target the various therapies available for treatment of NIDDM.

Alzheimer disease is not associated with polymorphisms in the angiotensinogen and renin genes.

Hypertension has been implicated as a risk factor for Alzheimer disease (AD) and dementia in epidemiological studies of humans. It is thus possible that there are common genetic determinants for hypertension and AD. Epidemiological, clinical, and experimental data suggest that the renin-angiotensin-aldosterone system is a critical regulator of blood pressure. The presence of an MboI site in an RFLP in the renin gene and the Thr at the Met/Thr polymorphism at codon 235 (M235T) of the angiotensinogen gene have been reported to be associated with hypertension. These variants were studied in autopsy-confirmed AD cases and matched controls from the U.K. While no association was detected with the renin polymorphism, a weak deleterious effect was observed in cases homozygous for the angiotensinogen Thr allele. However, this association was not observed in a French cohort of clinically diagnosed AD cases and controls, suggesting that the initial observation was a type I error. Thus, these polymorphisms are unlikely to be associated with AD risk.

The deletion allele of the angiotensin I converting enzyme gene as a genetic susceptibility factor for cognitive impairment.

Experimental evidences suggest an implication of the renin angiotensin system (RAS) as a potential determinant of cognitive functions. To explore this hypothesis, we compared the distribution of an insertion (I)/deletion (D) polymorphism of the gene coding for the angiotensin I converting enzyme (ACE), a key enzyme of the RAS, in 228 elderly with cognitive impairment to that of 255 controls. The ACE D allele frequency was higher in the group with cognitive impairment (0.594) than in controls (0.514) (P < 0.02). The ACE DD genotype carriers had an increased risk of cognitive impairment (OR = 1.60, 95% CI (1.04-2.36), P < 0.03), independent of other risk factors of cognitive impairment: age, gender and presence of the apolipoprotein E epsilon 4 allele. This association was stronger in men (OR = 3.25, 95% CI (1.40-7.58), P < 0.006). This result suggests a possible implication of the RAS in human brain and cognitive functions.

No association of the HLA-A2 allele with Alzheimer's disease.

A possible association of the human leucocyte antigen (HLA)-A2 allele with increased susceptibility to Alzheimer's disease (AD) has been the subject of debate for more than 20 years. We compared the presence of the HLA-A2 allele in a sample from the French population composed of 451 patients and 477 controls. There was no evidence of an association of this allele with increased risk of AD. Moreover, no effect was observed when we stratified the case-control sample on gender, age of onset or presence of an APOE epsilon4 allele. We conclude that HLA-A2 allele is not a major risk factor for sporadic AD.

A FE65 polymorphism associated with risk of developing sporadic late-onset alzheimer's disease but not with Abeta loading in brains.

The FE65 protein was previously described interacting with amyloid protein precursor (APP) and mediating its internalization. Hu et al. (Hum. Genet., 103 (1998) 295) recently reported that a deletion polymorphism in intron 13 of the FE65 gene may be protective for sporadic Alzheimer's disease (AD) forms and suggested that this deletion may modify splicing between exon 13 and 14 (the two exons encoding the interaction domain of FE65 with APP). We tested the impact of this polymorphism in 646 controls and 639 sporadic AD cases. We were only able to detect a protective effect of the deletion in the population over 75 years (odds ratio = 0.53, 95% confidence interval (0.35-0.82), P= 0.002). Furthermore, no association of this polymorphism with Abeta40, Abeta42(43) and total Abeta loads were detected in 74 AD brains, although, we could expect that this deletion was associated with modifications of the APP metabolism. In conclusion, the FE65 gene may be a minor genetic determinant only for sporadic late-onset AD forms, although, we cannot conclude that this impact is mediated by a modulation of the APP process and/or Abeta peptide deposition.

No association between the alpha-2 macroglobulin I1000V polymorphism and Alzheimer's disease.

Recent reports have suggested that variability in the alpha2-macroglobulin gene is a genetic risk factor for Alzheimer's disease. Here we have both tested a common polymorphism in the gene (I1000V) for association with the disease in a four-site case control study design, and tested the locus for linkage in a large series of sibpairs afflicted with late onset disease. Our results fail to show an association between this polymorphism and disease.

Types of alcoholic beverages and blood lipids in a French population.

STUDY OBJECTIVE: Prospective studies have shown a consistent relation between alcohol consumption and decreasing incidence of coronary artery disease. The protective effect of alcohol could be mediated through increased levels of HDL cholesterol (HDL-c). The aim of this study was to examine the relation between blood lipid levels and the consumption of different types of alcoholic beverages among 1581 men and 1535 women. DESIGN: Data from representative cross sectional surveys (1994-1997) in three different regions of France were used. The consumption of the different types of alcohol was quantified using a recall method according to a typical weekly consumption. MAIN RESULTS: The median daily alcohol intake was 24 g for men and 4 g for women. After adjustment for confounders, total alcohol showed a positive and significant association with HDL-c and triglycerides (TG) in both sexes. In multivariate analysis, wine was positively associated with HDL-c. Beer was positively associated with HDL-c in men and with triglycerides in men and women. When taking drinking patterns into account, wine drinkers had higher HDL-c levels than non-wine drinkers. Differences became non-significant after adjustment for confounders and particularly for socioeconomic parameters. CONCLUSIONS: In a French population sample, total alcohol was positively associated with HDL-c and triglycerides. The specific influence of any particular alcoholic beverage on blood lipids was not clearly demonstrated but wine preference found in a group with higher lifestyle standards was associated with a more favourable blood lipid profile.

Influence of parental histories of cardiovascular risk factors on risk factor clusters in the offspring.

OBJECTIVES: To assess the effect of parental histories of cardiovascular risk factors on risk factor clusters (RFC) in representative samples from three French populations (MONICA centers of Lille, Strasbourg, Toulouse). MATERIAL AND METHODS: In a representative cross-sectional study, we screened 1,291 males and 1,264 females, aged 35-64 years. Subjects were defined as RFC cases when they were affected by at least 2 disorders among, hypertension (systolic or diastolic blood pressure >=140/90 mmHg and/or antihypertensive drug), diabetes (physician-diagnosed diabetes and/or glycemia >=7.0 mmol/l and/or hypoglycemic drug), and dyslipidemia (triglycerides > 2.26 mmol/l and/or HDL-cholesterol<0.9 mmol/l in men and<1.2 mmol/l in women). Nineteen percent of the subjects were RFC cases. Parental histories of cardiovascular risk factors (hypertension, diabetes, hyperlipidemia) were positive if they were under 65. About 29% of the subjects had at least one parental history of risk factor. RESULTS: After adjustment for sex, age, educational level, sedentary lifestyle, alcohol consumption, body mass index, LDL cholesterol and center, parental histories of cardiovascular risk factors were significantly associated with the RFC. One, two, or at least three parental histories were significantly associated with increased odds of being RFC cases (adjusted OR 1.39 95% CI [1.05-1.82], 2.90 95% CI [1.91-4.40], 2.93 95% CI [1.41-6.08]). Furthermore, a maternal-only history vs a paternal-only history of hypertension or diabetes was associated with strong odds of being an RFC case. CONCLUSION: At least a single cardiovascular risk factor in parents was significantly associated with RFC in offspring, independently of environmental parameters.

Prevalence of type 2 diabetes and impaired fasting glucose in the middle-aged population of three French regions - The MONICA study 1995-97.

OBJECTIVES: The aim of this study was to determine the prevalence of type 2 diabetes and impaired fasting glucose (IFG) in a population-based sample of 3 508 subjects, aged 35-64 years, participating in the French MONICA population survey from 1995 to 1997 in three French regions: the Urban Community of Lille, the Bas-Rhin and the Haute-Garonne. MATERIAL AND METHODS: Previously diagnosed type 2 diabetes is defined by the current use of oral hypoglycaemic treatment and newly diagnosed subjects by fasting plasma glucose (FPG) > or =7.0 mmol/L according to the ADA 1997 recommendations. IFG was determined by 6.1< or =FPG< or =6.9 mmol/L. Adjusted prevalences are calculated according to the French 1990 census data. RESULTS: Type 2 diabetes adjusted prevalence is 5.1% [4.1-6.1] in women and 7.3% [6.1-8.4] in men while IFG adjusted prevalence is 5.2% [4.2-6.2] and 11.8% [10.3-13.4] respectively. Prevalences of type 2 diabetes and IFG are both significantly higher in men than in women. This trend appears in any age group for IFG, but is only observed in 55-64 year-old subjects for type 2 diabetes. The reduction of the FPG threshold to screen diabetes mellitus from 7.8 to 7.0 mmol/L according to the ADA recommendations results in a 2.2-fold increase in the number of newly diagnosed diabetic subjects, screened by one FPG measurement, in our population-based sample. CONCLUSIONS: The MONICA population survey confirms that type 2 diabetes represents a major health care problem in France and underlines the influence of gender on the prevalence of both type 2 diabetes and IFG in the French middle-aged population.

Influence of parental history of hypertension on blood pressure.

AIM: To assess the effect of parental history of hypertension on blood pressure in representative samples from three French populations (MONICA centres of Lille, Strasbourg, Toulouse). METHODS: We screened 1660 males and 1635 females, aged 35-64 years. Subjects were defined as hypertensive if systolic blood pressure >/=160 mm Hg or diastolic blood pressure >/=95 mm Hg or if they were treated by antihypertensive drugs. Four groups of parental history were determined: no parental history; at least one parent hypertensive before 60 years; hypertension was diagnosed after 60; and hypertension with unknown age of discovery. A logistic regression model was used separately for each sex. RESULTS: After adjustment for age, body mass index, physical exercise, educational level, tobacco consumption, alcohol consumption, high density lipoprotein cholesterol, centre, diabetes mellitus and hypercholesterolaemia, parental history before age 60 was related to offspring's hypertension: OR = 2.09 (95% CI: 1.42-3.09) in men, and OR = 2.77 (95% CI: 1.95-3.93) in women. This relationship was stronger when we compared two parental histories versus none (women: OR = 5.33, 95% CI: 1.30-21.94; men: OR = 7.78, 95% CI: 2.45-24.74). CONCLUSION: In this representative cross-sectional study, history of hypertension in at least one parent was associated with offspring's hypertension.

Attitudes toward healthy eating: a mediator of the educational level-diet relationship.

BACKGROUND/OBJECTIVES: A higher educational level is associated with a healthier diet. The goal of this study was to establish whether this association is mediated by attitudes toward healthy eating. SUBJECTS/METHODS: The cross-sectional MONA LISA-NUT study was performed in 2005-2007 on adults aged 35-64 years from northern and north-eastern France. Diet quality was assessed on the basis of a 3-day food record and a validated score based on French national dietary guidelines. Specific questions investigated attitudes toward healthy eating. Multivariate analyses were used to quantify the proportion of the educational level-diet relationship that was mediated by attitudes toward healthy eating. RESULTS: Among the 1631 subjects, favourable attitudes toward healthy eating were associated with both higher educational level and diet quality. In the mediation analysis, 'organic food consumption' explained 14% (95% confidence interval (8;24)) of the educational level-diet relationship and 'attention paid to health when buying food' explained 9% (3;16). In contrast, 'attention to food choice', 'searching for information about food' and 'perceived role of eating' were not mediators of the association between educational level and diet. In a multivariate model, the attitude items together accounted for 25% (10;45) of the relationship. The mediation was more pronounced in women than in men (37% (15;54) vs 16% (1;27), respectively) and was significant for consumption of fruits and vegetables (23% (13;37)), whole-grain food (32% (15;58)) and seafood (22% (9;55)). CONCLUSIONS: Our results suggest that poor attitudes toward healthy eating in groups with low socioeconomic status constitute an additional factor (along with cost constraints) in the choice of unhealthy foods.