Développement et validation d’outils méthodologiques de mesure de l’adhésion aux recommandations nutritionnelles

Les recommandations nutritionnelles visent l’amélioration de la qualité alimentaire par la promotion de saines habitudes. Les enquêtes de santé nous confirment toutefois que ces recommandations sont mal comprises et que le concept de qualité alimentaire crée de la confusion chez plusieurs personnes. L’objectif de ce projet était de développer et de valider deux outils visant à mesurer la qualité de l’alimentation. Le premier est un rappel de 24 heures sur plateforme web totalement automatisé qui vise à faciliter la collecte d’information des chercheurs en nutrition. Les stratégies de validation déployées impliquent l’observation directe de la prise alimentaire chez une soixantaine de sujets, la comparaison des aliments rapportés avec une autre technique bien établie et l’analyse de marqueurs sanguins reflétant certains apports alimentaires chez 150 sujets ainsi que la comparaison des apports avec des marqueurs reconnus de la santé métabolique chez un troisième groupe de près de 1000 sujets. Les travaux réalisés tendent à démontrer un bon niveau de validité pour la mesure des apports en énergie et en nutriments ainsi que pour décrire la qualité de l’alimentation. Le deuxième outil est un outil de dépistage qui a été développé en identifiant les choix alimentaires prédicteurs d’une bonne qualité alimentaire. Une séquence de quatre à six questions est dictée par un algorithme et chacune d’elles demande oui ou non comme réponse. Nos analyses ont mis en lumière que ce nouvel outil avait la spécificité et la sensibilité nécessaire pour servir à identifier les individus ayant des habitudes alimentaires sous-optimales. Il sera mis à la disposition des médecins de famille et des autres intervenants en première ligne afin de faciliter l’identification des individus dont la qualité alimentaire pourrait être optimisée et le référencement vers des nutritionnistes. Enfin, plusieurs réflexions plus larges sur la validité de la mesure des apports alimentaires ainsi que sur la définition de la qualité de l’alimentation ponctuent cet ouvrage.Dietary recommendations are aimed at improving food quality by promoting healthy habits. However, health surveys confirm that these recommendations are poorly understood and that the concept of food quality creates confusion for many people. The objective of this project was to develop and validate two tools aimed at measuring food quality. The first one is a fully automatic web-based 24-hour dietary recall that aims to facilitate data collection for researchers in the field of nutrition. The validation strategies deployed involve direct observation of food intake in around sixty subjects, comparison of reported intakes with another well-established technique and analysis of blood markers reflecting specific dietary intakes in 150 subjects as well as comparison of food intakes with recognized markers of metabolic health in a third group of nearly 1000 subjects. The work carried out tends to demonstrate a good level of validity for measuring energy and nutrient intakes as well as for describing diet quality. The second tool is a screening tool that has been developed by identifying food choices predicting good nutritional quality. A sequence of four to six questions is dictated by an algorithm and each of them can be answered by yes or no. Our analyzes revealed that this new tool had the adequate specificity and sensitivity to be used to identify individuals with suboptimal eating habits. It will be made available to family physicians and other primary care workers to facilitate the identification of individuals whose food quality could be improved and the referral to nutritionists. Finally, broader reflections on the validity of the measurement of food intake and on the definitions of diet quality are found throughout this thesis

Validation of a newly automated web-based 24-hour dietary recall using fully controlled feeding studies

BACKGROUND: Assessment of food intake is a cornerstone of nutritional research. However, the use of minimally validated dietary assessment methods is common and can generate misleading results. Thus, there is a need for valid, precise and cost-effective dietary assessment tools to be used in large cohort studies. The objective is to validate a newly developed automated self-administered web-based 24-h dietary recall (R24W), within a population of adults taking part in fully controlled feeding studies. METHODS: Sixty two adults completed the R24W twice while being fed by our research team. Actual intakes were precisely known, thereby allowing the analysis of the proportion of adequately self-reported items. Association between offered and reported portion sizes was assessed with correlation coefficients and agreement with the kappa score while systematics biases were illustrated with Bland-Altman Plot. RESULTS: Participants received an average of 16 food items per testing day. They reported 89.3% of the items they received. The more frequently omitted food categories were vegetables included in recipes (40.0%) as well as side vegetables (20.0%) and represented less than 5% of the actual daily energy intake. Offered and self-reported portion sizes were significantly correlated (r = 0.80 P < 0.001) and demonstrated a strong agreement as assessed by the kappa score of 0.62. Reported portion sizes for individual food items were on average 3.2 g over the offered portion sizes. Portions of 100 g and above were on average underestimated by 2.4% (r = 0.68 P < 0.01; kappa score = 0.50) while small portions (less than 100 g) were overestimated by 17.1% (r = 0.46 P < 0.01; kappa score = 0.43). A nonsignificant underestimation (−13.9 kcal ± 646.3 kcal; P = 0.83) of energy intake was noted. CONCLUSION: R24W performed well as participants were able to report the great majority of items they ate and selected portion size strongly related to the one they received. This suggests that food items are easily to find within the R24W and images of portion sizes used in this dietary assessment tool are adequate and can provide valid food intake evaluation

Are French Canadians able to accurately self-rate the quality of their diet? Insights from the PREDISE study

Cette étude se propose principalement de comparer l’autoévaluation de la qualité du régime alimentaire à un score de qualité nutritionnelle globale et à évaluer la prédictibilité de l’autoévaluation concernant l’adhésion aux recommandations de saine alimentation. Cette étude examine aussi la possible influence des caractéristiques individuelles sur l’association entre l’autoévaluation du régime alimentaire et le score de qualité nutritionnelle globale. Dans le cadre du projet PRédicteurs Individuels, Sociaux et Environnementaux (PREDISE), 1045 participants (51 % femmes) du Québec (Canada) ont autoévalué la qualité de leur régime alimentaire (« En général, diriez-vous que vos habitudes alimentaires sont : excellentes, très bonnes, bonnes, passables ou mauvaises? »). Les données de trois rappels alimentaires de 24 h via Internet ont permis le calcul du Healthy Eating Index (C-HEI), un indicateur de qualité nutritionnelle globale. Les participants percevaient leurs habitudes alimentaires comme étant excellentes (2,4 %), très bonnes (22,7 %), bonnes (49,5 %), passables (20,3 %) ou mauvaises (5,1 %). Le C-HEI variait significativement entre les catégories d’autoévaluation dans la direction attendue (p 68) de saine alimentation en présentant une sensibilité de 44,5 % et une spécificité de 81,5 % (statistique C = 0,63). L’association entre l’autoévaluation et le C-HEI était modifiée significativement par le sexe (p interaction = 0,0131); les femmes avaient un C-HEI plus élevé que les hommes dans les catégories « bonnes » et « passables ». L’autoévaluation du régime alimentaire permet de donner un aperçu de la qualité du régime alimentaire d’une population. Cependant, les résultats de cette étude suggèrent d’utiliser ces données avec prudence compte tenu de leur faible prédictibilité concernant l’adhésion aux recommandations de saine alimentation. Des caractéristiques individuelles sont susceptibles d’influencer l’aptitude à autoévaluer adéquatement la qualité du régime alimentaire.The main objective of this study was to compare self-rated diet quality to a more comprehensive score of diet quality and to assess the ability of self-rated diet quality to predict adherence to healthy eating guidelines. This study also aimed at evaluating the influence of individual characteristics on the association between self-rated diet quality and the overall diet quality score. As part of the PREDISE study, 1045 participants (51% women) from the Province of Québec, Canada, self-rated their diet quality (“In general, would you say that your dietary habits are: excellent, very good, good, fair, or poor?”). Three web-based 24-hour food recalls were completed, generating data for the calculation of the Canadian Healthy Eating Index (C-HEI), an overall diet quality indicator. Participants rated their diet quality as excellent (2.4%), very good (22.7%), good (49.5%), fair (20.3%) or poor (5.1%). The C-HEI significantly differed between diet ratings, in the expected direction (p<0.0001). Self-rated diet quality predicted adherence to healthy eating guidelines (i.e. C-HEI>68) with a sensitivity of 44.5% and a specificity of 81.5% (c-statistic=0.63). Sex significantly modified the association between self-rated diet quality and C-HEI (p interaction=0.0131); women had higher C-HEI than men in the “good” and “fair” ratings. Self-rated diet quality can be useful to obtain an overview of the diet quality of a population. Results of this study suggest that such data should be used with caution given its poor ability to predict adherence to healthy eating guidelines. Individual characteristics may influence one’s ability to appropriately self-evaluate diet quality

Les caroténoïdes sériques comme biomarqueurs : une stratégie pour améliorer la validité de l’évaluation alimentaire

La marge d’erreur dans l’évaluation de la prise alimentaire au moyen des outils traditionnels comme le rappel de 24h, le questionnaire de fréquence et le journal alimentaire est grande et peut conduire à l’interprétation erronée de résultats de recherche. La recherche sur des biomarqueurs associés à la consommation de fruits et de légumes a le potentiel d’améliorer sensiblement la validité de l’évaluation de la prise alimentaire ainsi que la mesure des associations entre la qualité nutritionnelle et la santé. Les caroténoïdes, des pigments issus presque exclusivement du monde végétal, présentent un intérêt grandissant dans ce domaine. Les caractéristiques des caroténoïdes ainsi que les avantages et les défis que pose leur utilisation dans l’évaluation nutritionnelle seront développés dans la présente revue

Validity of a new 24-hour dietary recall

Objective : To assess the relative validity of a new, web-based, self-administered 24 h dietary recall, the R24W, for assessment of energy and nutrient intakes among French Canadians. Design : Each participant completed a 3d food record (FR) and the R24W on three occasions over a 4-week period. Intakes of energy and of twenty-four selected nutrients assessed by both methods were compared. Setting : Québec City metropolitan area. Subjects : Fifty-seven women and fifty men (mean (sd) age: 47·2 (13·3) years). Results : Equivalent proportions of under-reporters were found with the R24W (15·0%) and the FR (23·4%). Mean (sd) energy intake from the R24W was 7·2% higher than that from the FR (10 857 (3184) kJ/d (2595 (761) kcal/d) v. 10 075 (2971) kJ/d (2408 (710) kcal/d); P<0·01). Significant differences in mean nutrient intakes between the R24W and the FR ranged from –54·8% (i.e. lower value with R24W) for niacin to +40·0% (i.e. higher value with R24W) for alcohol. Sex- and energy-adjusted deattenuated correlations between the two methods were significant for all nutrients except Zn (range: 0·35–0·72; P<0·01). Cross-classification demonstrated that 40·0% of participants were classified in the same quartile with both methods, while 40·0% were classified in the adjacent quartile and only 3·6% were grossly misclassified (1st v. 4th quartile). Analysis of Bland–Altman plots revealed proportional bias between the two assessment methods for 8/24 nutrients. Conclusions : These data suggest that the R24W presents an acceptable relative validity as compared with the FR for estimating usual dietary intakes in a cohort of French Canadians

Relative validity of a web-based, self-administered, 24-hour dietary recall to evaluate adherence to Canadian dietary guidelines

Objectives: A new, web-based, 24-h recall (R24 W) was developed and programmed to assess adherence to Canadian dietary guidelines by automatically generating the Canadian Healthy Eating Index 2007 (C-HEI 2007). The aim of the present study was to determine the relative validity of the R24 W in terms of its ability to generate C-HEI 2007 scores that match those derived from a food record (FR). Methods: A total of 57 women and 50 men filled a 3-d FR and three 24-h food recalls with the R24 W. C-HEI 2007 was calculated with both dietary assessment tools and compared using de-attenuated correlations and kappa scores. Internal validity (correlations between total score and components) and external validity (comparison of the C-HEI 2007 by sex and age groups) were compared between the two dietary assessment methods. Results: The average C-HEI 2007 score obtained with the R24 W (59.4 ± 11.8) was significantly lower than the one obtained with the FR (62.6 ± 11.1). However, the de-attenuated correlation coefficient between C-HEI 2007 obtained either with R24 W or FR was 0.80 (P 51 y) received a higher score than younger adults (age: 18-30 y; P < 0.01) with the R24 W but not with the FR (P = 0.22). Conclusions: Although the R24 W yields lower C-HEI 2007 scores compared with data from FR, the classification of individuals was highly consistent between the two measurements

Associations between self-reported vegetable and fruit intake assessed with a new web-based 24-h dietary recall and serum carotenoids in free-living adults: a relative validation study

The aim of the present study was to assess the relative validity of a new web-based 24-h dietary recall (R24W) in terms of vegetable and fruit (VF) intake assessment using serum carotenoid concentrations as reference biomarkers. A total of seventy-four women and seventy-three men (mean age 47·5 (sd 13·3) years; mean BMI 25·5 (sd 4·4) kg/m2) completed the R24W four times to assess their VF intake. Serum carotenoids were obtained from 12-h fasted blood samples and measured by HPLC. Raw and de-attenuated partial Spearman's correlations were performed to determine how usual vegetable and/or fruit intake was associated with serum carotenoids. Relevant confounders were selected using a stepwise regression analysis. Finally, cross-classification was used to determine agreement between intake of VF and serum carotenoids. Intake of total dietary carotenoids was significantly associated (r 0·40; P < 0·01) with total serum carotenoids (without lycopene). Total VF intake was also associated with total serum carotenoid concentrations without lycopene (r 0·44; P < 0·01). HDL-cholesterol, waist circumference and age were identified as confounders in the association between total VF intake and total serum carotenoids (without lycopene). De-attenuated partial correlation adjusted for these confounders increased the associations between dietary carotenoids and total serum carotenoids without lycopene (r 0·49; P < 0·01) and between total VF intake and total serum carotenoids without lycopene (r 0·48; P < 0·01). Almost 80 % of respondents were classified in the same or the adjacent quartile for total VF intake and total serum carotenoids without lycopene, while less than 6 % were classified in the opposite quartile. Overall, these observations support the appropriateness of the R24W to assess the dietary intake of VF

Validation of a self-administered web-based 24-hour dietary recall among pregnant women

Abstract Background The use of valid dietary assessment methods is crucial to analyse adherence to dietary recommendations among pregnant women. This study aims to assess the relative validity of a self-administered Web-based 24-h dietary recall, the R24W, against a pen-paper 3-day food record (FR) among pregnant women. Methods Sixty (60) pregnant women recruited at 9.3 ± 0.7 weeks of pregnancy in Quebec City completed, at each trimester, 3 R24W and a 3-day FR. Mean energy and nutrient intakes reported by both tools were compared using paired Student T-Tests. Pearson correlations were used to analyze the association between both methods. Agreement between the two methods was evaluated using cross-classification analyses, weighted kappa coefficients and Bland-Altman analyses. Results Pearson correlation coefficients were all significant, except for vitamin B12 (r = 0.03; p = 0.83) and ranged from 0.27 to 0.76 (p < 0.05). Differences between mean intakes assessed by the R24W and the FR did not exceed 10% in 19 variables and were not significant for 16 out of 26 variables. In cross-classification analyses, the R24W ranked, on average, 79.1% of participants in the same or adjacent quartiles as the FR. Conclusions Compared to a 3-day FR, the R24W is a valid method to assess intakes of energy and most nutrients but may be less accurate in the evaluation of intakes of fat (as a proportion of energy intake), vitamin D, zinc and folic acid. During pregnancy, the R24W was a more accurate tool at a group-level than at an individual-level and should, therefore, be used in an epidemiological rather than a clinical setting. The R24W may be particularly valuable as a tool used in cohort studies to provide valid information on pregnant women’s dietary intakes and facilitate evaluation of associations between diet and adverse pregnancy outcomes