Chantal Julia

Validity of Web-Based Self-Reported Weight and Height: Results of the Nutrinet-Santé Study

Background With the growing scientific appeal of e-epidemiology, concerns arise regarding validity and reliability of Web-based self-reported data. Objective The objectives of the present study were to assess the validity of Web-based self-reported weight, height, and resulting body mass index (BMI) compared with standardized clinical measurements and to evaluate the concordance between Web-based self-reported anthropometrics and face-to-face declarations. Methods A total of 2513 participants of the NutriNet-Santé study in France completed a Web-based anthropometric questionnaire 3 days before a clinical examination (validation sample) of whom 815 participants also responded to a face-to-face anthropometric interview (concordance sample). Several indicators were computed to compare data: paired t test of the difference, intraclass correlation coefficient (ICC), and Bland–Altman limits of agreement for weight, height, and BMI as continuous variables; and kappa statistics and percent agreement for validity, sensitivity, and specificity of BMI categories (normal, overweight, obese). Results Compared with clinical data, validity was high with ICC ranging from 0.94 for height to 0.99 for weight. BMI classification was correct in 93% of cases; kappa was 0.89. Of 2513 participants, 23.5% were classified overweight (BMI≥25) with Web-based self-report vs 25.7% with measured data, leading to a sensitivity of 88% and a specificity of 99%. For obesity, 9.1% vs 10.7% were classified obese (BMI≥30), respectively, leading to sensitivity and specificity of 83% and 100%. However, the Web-based self-report exhibited slight underreporting of weight and overreporting of height leading to significant underreporting of BMI (P<.05) for both men and women: –0.32 kg/m2 (SD 0.66) and –0.34 kg/m2 (SD 1.67), respectively. Mean BMI underreporting was –0.16, –0.36, and –0.63 kg/m2 in the normal, overweight, and obese categories, respectively. Almost perfect agreement (ie, concordance) was observed between Web-based and face-to-face report (ICC ranged from 0.96 to 1.00, classification agreement was 98.5%, and kappa 0.97). Conclusions Web-based self-reported weight and height data from the NutriNet-Santé study can be considered as valid enough to be used when studying associations of nutritional factors with anthropometrics and health outcomes. Although self-reported anthropometrics are inherently prone to biases, the magnitude of such biases can be considered comparable to face-to-face interview. Web-based self-reported data appear to be an accurate and useful tool to assess anthropometric data.

Carotenoid-rich dietary patterns during midlife and subsequent cognitive function

Carotenoids may help to prevent the ageing of the brain. Previous findings regarding β-carotene alone are not consistent. In the present study, we evaluated the cross-time association between a carotenoid-rich dietary pattern (CDP) and subsequent cognitive performance using a sample of 2983 middle-aged adults participating in the SU.VI.MAX (Supplémentation en Vitamines et Minéraux Antioxydants) study. Cognitive performance was assessed in 2007-9 using six neuropsychological tests, and a composite cognitive score was computed. The cognitive data were related to dietary data obtained by repeated 24 h dietary records (1994-6) and to measurements of baseline plasma concentrations of carotenoids (lutein, zeaxanthin, β-cryptoxanthin, lycopene, α-carotene, trans-β-carotene and cis-β-carotene). DP were extracted using the reduced rank regression method for 381 participants and then extrapolated to the whole sample using plasma carotenoid concentrations as response variables. Associations between a CDP and cognitive function measured 13 years later were estimated with ANCOVA providing mean difference values and 95 % CI across the tertiles of CDP. A correlation between CDP and consumption of orange- and green-coloured fruits and vegetables, vegetable oils and soup was observed. CDP was found to be associated with a higher composite cognitive score (mean difference 1·04, 95 % CI 0·20, 1·87, P for trend 0·02), after adjustment for sociodemographic, lifestyle and health factors. Similar findings were obtained for scores obtained in the cued recall task, backward digit span task, trail making test and semantic fluency task (all P for trend < 0·05). Further studies ought to confirm whether a diet providing sufficient quantity and variety of coloured fruits and vegetables may contribute to the preservation of cognitive function during ageing.

Prospective association between the dietary inflammatory index and metabolic syndrome: Findings from the SU.VI.MAX study

BACKGROUND AND AIMS The prevention of the metabolic syndrome (MetS) is of major concern and nutrition has been shown to modulate at least partly MetS risk. Our objective was to investigate whether a pro-inflammatory diet was associated with a higher risk of MetS and its components in a large cohort of French adults. METHODS AND RESULTS A total of 3726 participants from the Supplémentation en Vitamines et Minéraux AntioXydants (SU.VI.MAX) cohort were included in this study. The MetS status was identified at baseline and after 13 years of follow-up using self-reported medication, data from clinical investigations and biological measurements. The dietary inflammatory index (DII) was computed using repeated 24 h-dietary records (n = 10.1 ± 3.1). Logistic and linear regression analyses were conducted to assess the prospective association of the DII (as Q, quartiles) with the incidence of MetS and with the traits contributing to the MetS-definition (blood pressure, glycaemia, triglycerides, HDL-cholesterol, waist circumference). A diet with pro-inflammatory properties, as expressed by higher DII scores, was significantly associated with a higher risk of developing the MetS (OR comparing Q4 to Q1: 1.39, 95% confidence interval 1.01-1.92, P = 0.047). Moreover, higher DII scores were associated with higher systolic and diastolic blood pressure (Ptrend across quartiles = 0.03 and 0.05, respectively) and triglycerides (Ptrend = 0.01), and with lower HDL-cholesterol (Ptrend = 0.03). CONCLUSION A higher DII score was prospectively associated with a higher risk of MetS, with associations with blood pressure, triglycerides and HDL-cholesterol. Promotion of a healthy diet exhibiting anti-inflammatory properties may contribute to prevent cardio-metabolic disorders.

Association between Adherence to Nutritional Guidelines, the Metabolic Syndrome and Adiposity Markers in a French Adult General Population

Introduction Few studies have focused on the association between diet quality scores and the Metabolic Syndrome (MetS), a multi-component condition predictive of cardiovascular diseases (CVD) and death. The present study aims at investigating, in a cross-sectional design, the association between adherence to the French dietary guidelines through an a priori score – the French Nutrition and Health Program-Guideline Score (PNNS-GS) – and cardiovascular risk factors (CVRF) including the MetS and adiposity markers. Methods 7902 French adults participating in the NutriNet-Santé study (an on-going web-based cohort study) attended a clinical and biological examination between January 2011 and November 2012: a fasting blood sample was drawn, blood pressure and body composition (bio-impedance) were measured. Multivariate linear and logistic regression models were used to assess the association between PNNS-GS and CVRF or the MetS. Results An increase of PNNS-GS was significantly negatively associated with waist circumference (WC), systolic and diastolic blood pressure (SBP and DBP) and serum triglycerides concentrations. From bottom to top quartile of PNNS-GS, SBP decreased from 129.9 to 128.8 mm Hg, DBP from 76.7 to 75.9 mm Hg, serum triglycerides concentrations from 110.8 to 104.6 mg/dL and WC from 94.8 to 90.1 cm for men and 81.3 to 78.9 cm for women. All adiposity markers (waist and hip circumference, % body fat, % trunk fat, % leg fat) were markedly reduced across quartiles of PNNS-GS and linearly. Individuals with a better PNNS-GS (quartile 4 vs quartile 1) were less likely to have the MetS (OR=0.71, 95% CI: 0.56-0.89). Conclusion The negative association between a higher adherence to the French dietary guidelines and a number of CVRF, the MetS prevalence and regional adiposity supports the importance of promoting the PNNS dietary guidelines in the population for the prevention of cardiometabolic abnormalities and hence, cardiovascular diseases.

Supplementation with B vitamins or n−3 fatty acids and depressive symptoms in cardiovascular disease survivors: ancillary findings from the SUpplementation with FOLate, vitamins B-6 and B-12 and/or OMega-3 fatty acids (SU.FOL.OM3) randomized trial

BACKGROUND Dietary factors might affect depressive symptoms. OBJECTIVE In secondary data analyses, we examined effects of supplementation with B vitamins or n-3 (omega-3) fatty acids on depressive symptoms in cardiovascular disease survivors. DESIGN The SUpplementation with FOLate, vitamins B-6 and B-12 and/or OMega-3 fatty acids (SU.FOL.OM3) trial was a secondary prevention trial (2003-2009; n = 2501) in which individuals aged 45-80 y were randomly assigned, by using a 2 × 2 factorial design, to receive 0.56 mg 5-methyl-tetrahydrofolate and vitamins B-6 (3 mg) and B-12 (0.02 mg); EPA and DHA (600 mg) in a 2:1 ratio; B vitamins and n-3 fatty acids; or a placebo. Depressive symptoms were evaluated at years 3 and 5 with the 30-item Geriatric Depression Scale (GDS). Overall and sex-specific ORs and 95% CIs were estimated in 2000 participants by using factorial logistic regression. RESULTS After a median of 4.7 y of supplementation, there was no association between allocation to receive B vitamins and depressive symptoms. However, the allocation to receive n-3 fatty acids was positively associated with depressive symptoms (GDS >10) in men (adjusted OR: 1.28; 95% CI: 1.03, 1.61) but not in women. CONCLUSIONS We showed no beneficial effects of a long-term, low-dose supplementation with B vitamins or n-3 fatty acids on depressive symptoms in cardiovascular disease survivors. The adverse effects of n-3 fatty acids in men merit confirmation.

Functional gastrointestinal disorders in 35,447 adults and their association with body mass index.

Functional gastrointestinal disorders’ (FGIDs) associations with body mass index (BMI) have not been thoroughly investigated in the general population.

Development and Validation of an Individual Dietary Index Based on the British Food Standard Agency Nutrient Profiling System in a French Context

BACKGROUND Nutrient profiling systems could be useful public health tools as a basis for front-of-package nutrition labeling, advertising regulations, or food taxes. However, their ability beyond characterization of foods to adequately characterize individual diets necessitates further investigation. OBJECTIVES The objectives of this study were 1) to calculate a score at the individual level based on the British Food Standard Agency (FSA) food-level nutrient profiling system of each food consumed, and 2) to evaluate the validity of the resulting diet-quality score against food group consumption, nutrient intake, and sociodemographic and lifestyle variables. METHODS A representative sample of the French population was selected from the NutriNet-Santé Study (n = 4225). Dietary data were collected through repeated 24-h dietary records. Sociodemographic and lifestyle data were self-reported. All foods consumed were characterized by their FSA nutrient profile, and the energy intake from each food consumed was used to compute FSA-derived aggregated scores at the individual level. A score of adherence to French nutritional recommendations [Programme National Nutrition Santé guideline score (PNNS-GS)] was computed as a comparison diet-quality score. Associations between food consumption, nutritional indicators, lifestyle and sociodemographic variables, and quartiles of aggregated scores were investigated using ANOVAs and linear regression models. RESULTS Participants with more favorable scores consumed higher amounts of fruits [difference Δ = 156 g/d between quartile 1 (less favorable) and quartile 4 (most favorable), P < 0.001], vegetables (Δ = 85 g/d, P < 0.001), and fish, and lower amounts of snack foods (Δ = -72 g/d, P < 0.001 for sugary snacks); they also had higher vitamin and mineral intakes and lower intakes of saturated fat. Participants with more favorable scores also had a higher adherence to nutritional recommendations measured with the PNNS-GS (Δ = 2.13 points, P < 0.001). Women, older subjects, and higher-income subjects were more likely to have more favorable scores. CONCLUSION Our results show adequate validity of the FSA nutrient profiling system to characterize individual diets in a French context. The NutriNet-Santé Study was registered in the European Clinical Trials Database (EudraCT) as 2013-000929-31.

Dietary patterns and risk of elevated C-reactive protein concentrations 12 years later

Inflammation mediates several chronic diseases. Micronutrients can act on inflammation, either through modulating cytokine production or by scavenging by-products of activated white cells. Identifying dietary patterns (DP) reflecting these mechanisms and relating them to inflammation is of interest. The objective of the study was to identify DP specifically associated with intakes of nutrients potentially involved in inflammatory processes in a middle-aged population and investigate long-term associations between these DP and C-reactive protein (CRP) status assessed several years later. Subjects included in the Supplementation in Vitamins and Mineral Antioxidants 2 cohort study, having available data on dietary assessment carried out in 1994-5 and CRP measurement in 2007-9, were included in the analysis. DP were extracted with reduced rank regression (RRR), using antioxidant micronutrients and PUFA as response variables. Associations between CRP measurements >3 mg/l and extracted DP were then examined with logistic regression models providing OR and 95% CI. A total of 2031 subjects (53·2% women, mean follow-up duration: 12·5 years) were included in the analyses. Of the four extracted DP, a DP with high loading values of vegetables and vegetable oils, leading to high intakes of antioxidant micronutrients and essential fatty acids, was significantly and negatively associated with risk of elevated CRP (OR 0·88; 95% CI 0·78, 0·98). Conversely, a DP reflecting a high n-6:n-3 fatty acid intake ratio was positively and significantly associated with elevated CRP (adjusted OR 1·15; 95% CI 1·00, 1·32). DP extracted with RRR provide support for further exploration of relationships between dietary behaviour and inflammation.

Prospective association between the Dietary Inflammatory Index and mortality: modulation by antioxidant supplementation in the SU.VI.MAX randomized controlled trial

BACKGROUND Chronic inflammation is a central mechanism involved in cardiovascular diseases, cancer, diabetes, and chronic respiratory diseases, 4 leading causes of mortality. Diet is a major source of pro- and anti-inflammatory bioactive compounds. The Dietary Inflammatory Index (DII) was designed to estimate the overall inflammatory potential of the diet. OBJECTIVE Our aim was to study the prospective association between the DII and mortality, as well as assess whether antioxidant supplementation could modulate this association. DESIGN The Supplémentation en Vitamines et Minéraux Antioxydants study was a randomized, double-blind, placebo-controlled trial in which participants received low-dose antioxidants or a placebo from 1994 to 2002. In this observational prospective analysis, 8089 participants (mean ± SD age at baseline: 49.0 ± 6.3 y) were followed between 1994 and 2007 (median: 12.4 y). The DII was calculated from repeated 24-h dietary records; higher scores correspond to more proinflammatory diets. A total of 207 deaths occurred during follow-up, including 123 due to cancer and 41 due to cardiovascular events. Multivariate Cox proportional hazards models were computed. RESULTS Sex-specific tertiles of the DII were positively associated with cardiovascular + cancer mortality (HR for tertile 3 compared with tertile 1 = 1.53; 95% CI: 1.01, 2.32; P-trend = 0.05) and specific cancer mortality (HR for tertile 3 compared with tertile 1 = 1.83; 95% CI: 1.12, 2.99; P-trend = 0.02). The corresponding P value was 0.07 for all-cause mortality. The DII was statistically significantly associated with increased all-cause mortality in the placebo group (HR for tertile 3 compared with tertile 1 = 2.10; 95% CI: 1.15, 3.84; P-trend = 0.02) but not in the antioxidant-supplemented group (P-trend = 0.8; P-interaction = 0.098). CONCLUSION These results suggest that a proinflammatory diet is associated with increased all-cause and cancer mortality and antioxidants may counteract some of the proinflammatory effects of the diet. This trial was registered at clinicaltrials.gov as NCT00272428.

Intakes of PUFAs Were Inversely Associated with Plasma C-Reactive Protein 12 Years Later in a Middle-Aged Population with Vitamin E Intake as an Effect Modifier

Although n-3 (ω-3) polyunsaturated fatty acids (PUFAs) are considered anti-inflammatory components, the role of dietary n-6 PUFAs in inflammation remains controversial. Some mechanistic evidence suggests vitamin E as a potential effect modifier in the relationship between PUFAs and inflammation. Our objectives were to evaluate the long-term associations between dietary intakes of PUFAs and elevated plasma C-reactive protein (CRP) and to investigate potential effect modification by vitamin E. Individuals in the placebo group of the SU.VI.MAX trial who had available CRP measurements in 2007-2009 were included in the study (n = 843). Dietary intakes of n-3 PUFAs, n-6 PUFAs, and vitamin E were assessed in 1994-1996 with at least 6 dietary records. The logistic regression OR for elevated CRP (>3 mg/L) and 95% CI were estimated for individual PUFAs and for total n-3 and n-6 PUFA intakes. Models were adjusted for sociodemographical, lifestyle, anthropometric, and dietary variables. Interactions with vitamin E intakes were also assessed. Inverse associations were observed between intakes of total n-3 PUFAs [α-linolenic acid (ALA; 18:3n-3), ALA + eicosapentaenoic acid (EPA; 20:5n-3), EPA + docosapentaenoic acid (DPA; 22:5n-3), DPA + docosahexaenoic acid (DHA; 22:6n-3)] and n-6 PUFA [linoleic acid (18:2n-6) + arachidonic acid (20:4n-6)] and elevated CRP (OR for tertile 3 vs. tertile 1 of intake: 0.41; 95% CI: 0.21, 0.77; P-trend = 0.01; and OR 0.38; 95% CI: 0.21, 0.70; P-trend = 0.002, respectively). Stratification on vitamin E intakes showed that inverse associations between dietary n-3 and n-6 PUFA intakes and elevated CRP were substantial only in individuals with low intakes of vitamin E. Our results supported the contention that intakes of both n-3 and n-6 PUFAs are inversely associated with plasma CRP concentrations. Vitamin E is a potential effect modifier and should therefore be taken into account in such investigations. This trial was registered at clinicaltrials.gov as NCT00272428.