De nombreux travaux epidemiologiques d’observation suggerent qu’un apport faible en antioxydants est associe a un risque plus eleve de cancers et de maladies cardiovasculaires. Cependant, les resultats des essais d’intervention publies dans ce domaine n’ont pas permis de confirmer ces hypotheses.L’etude SU.VI.MAX est une etude epidemiologique longitudinale avec un essai controle (essai randomise en double aveugle), ayant teste sur des sujets presumes sains l’impact sur 8 ans d’un apport quotidien d’antioxydants a des doses nutritionnelles, accessibles par l’alimentation (betacarotene : 6 mg, vitamine C : 120 mg, vitamine E : 30 mg, selenium : 100 μg et zinc : 20 mg), sur l’incidence des cardiopathies ischemiques et des cancers et sur la mortalite. La cohorte SU.VI.MAX etait composee de 13 017 sujets : 7 886 femmes âgees de 35 a 60 ans et 5 141 hommes de 45 a 60 ans. Les sujets ont ete suivis pendant une duree moyenne de 7,5 ans.Il n’a pas ete retrouve de difference entre les groupes en ce qui concerne l’incidence des cancers tous sites confondus (266 [4,1 %] pour le groupe antioxydants versus 295 [4,5 %] pour le groupe placebo), les maladies cardiovasculaires ischemiques (134 [2,1 %] versus 137 [2,1 %]), et la mortalite totale (76 [1,2 %] versus 98 [1,5 %]). Une interaction entre le groupe de supplementation et le sexe est retrouvee pour l’effet sur les cancers (p = 0,004). L’analyse stratifiee par sexe met en evidence un effet protecteur des antioxydants chez les hommes (RR = 0,69, 95 % IC : 0,53-0,91), mais pas chez les femmes (RR = 1,04, 95 % IC : 0,85-1,29). La meme tendance a ete observee pour la mortalite globale (p = 0,11, RR = 0,63 [0,42-0,93] chez les hommes et RR = 1,03 [0,64-1,03] chez les femmes).Au total, apres 7,5 ans de supplementation, il n’a pas ete retrouve d’effet des antioxydants sur l’incidence des cardiopathies ischemiques. Mais une diminution du risque de cancers (tous sites confondus) et de deces a ete observee chez les hommes ayant recu les antioxydants, a doses nutritionnelles. Aucun effet n’a ete observe chez les femmes.
The objective of the present work was to assess the relationship between serum Se concentrations and environmental determinants (i.e. lifestyle, social activity, geographic region, urban status, education, familial status, physical activity, BMI, tobacco, and food and alcohol consumption). Baseline results from 13 017 subjects (7876 women aged 35-60 and 5141 men aged 45-60) who participated in the SU.VI.M.AX (Supplémentation en Vitamines et Minéraux Antioxydants) study were analysed. Fewer than 2 % of the volunteers had a serum Se status under 0.75 micromol/l, which has been quoted as the cut-off of biological Se sub-deficiency. Women had significantly lower serum Se concentrations than men (1.09 (sd 0.19) micromol/l (n 7423) and 1.14 (sd 0.20) micromol/l (n 4915), P<0.0001, respectively). Significant differences in serum Se concentrations were observed between geographic areas. In both sexes, the serum Se concentration increased with alcohol, meat and fish consumption, and decreased with smoking. In premenopausal women, the serum Se concentration was higher in contraceptive-pill users than in non-users. In women only, age was associated with increased serum Se concentrations, and obesity (BMI> or =30 kg/m2) was associated with decreased serum Se levels. In men, we observed a decrease in serum Se concentrations with increased consumption of vegetables and fruits. In conclusion, though few of the volunteers participating in the SU.VI.M.AX study had Se status in the sub-deficiency range, 83 % of women and 75 % of men had serum concentrations below the value considered optimal for glutathione peroxidase activity. The largest Se associations in both sexes were found with regions, smoking, alcohol, meat and fish consumption. Further studies are needed to understand the difference in Se status between genders.
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Read moreWhereas the feasibility and effectiveness of Internet-based epidemiologic research have been established, methodological support for the quality of such data is still accumulating. We aimed to identify sociodemographic differences among members of a French cohort according to willingness to provide part of one's 15-digit national identification number (personal Social Security number (PSSN)) and to assess response consistency based on information reported on the sociodemographic questionnaire and that reflected in the PSSN. We studied 100,118 persons enrolled in an Internet-based prospective cohort study, the NutriNet-Santé Study, between 2009 and 2013. Persons aged 18 years or more who resided in France and had Internet access were eligible for enrollment. The sociodemographic profiles of participants with discordant data were compared against those of participants with concordant data via 2-sided polytomous logistic regression. In total, 84,442 participants (84.3%) provided the first 7 digits of their PSSN, and among them 5,141 (6.1%) had discordant data. Our multivariate analysis revealed differences by sex, age, education, and employment as regards response consistency patterns. The results support the quality of sociodemographic data obtained online from a large and diverse volunteer sample. The quantitative description of participant profiles according to response consistency patterns could inform future methodological work in e-epidemiology.
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