Validity of questionnaires to assess fruit and vegetable consumption in children when compared with blood biomarkers: a systematic review

Abstract

The intake of fruits and vegetables is essential to help maintaining a healthy weight and promoting cardiovascular health in children. Different instruments are used to measure dietary intake such as food frequency questionnaires and 24-hour recalls, but they are subjective and could present errors. Therefore, testing the validity of these instruments is key. The objective of this project is to perform a systematic review of validation criteria of questionnaires used to assess fruit and vegetable consumption in school-aged children, utilizing blood biomarkers as the reference method. Searches are going to be executed in five electronic databases (MEDLINE, CINAHL, Scopus, PsycINFO, Web of Science), using the following descriptors and medical terms: (Child OR Children OR school OR boy OR son OR girl OR daughter) AND (Fruit OR Vegetable) AND (Questionnaire OR 24h Dietary Recall OR 24h-Dietary-Recall OR 24 hour Dietary Recall OR Recall OR Food Frequency Questionnaire OR FFQ) AND (Biomarker OR Blood OR concentration biomarker OR serum OR serum marker OR carotenoids OR vitamins) AND (Validation OR Validity OR coefficient OR reliability). Articles are going to be screened and selected by title, abstract and, posteriorly, read in full to determine whether they meet inclusion criteria. We are planning to perform a meta-regression analysis, but this depends on the possibility of the articles being compared and summarizing the validation coefficients. To identify an a priori hypothesis, the sample-weighted pooled correlation coefficient will be calculated by meta-analysis with a fixed or random-effects model due to the moderate-to-high heterogeneity found study-by-study and biomarker-by-biomarker. The florets plot will be calculated by meta-regression analysis to summarize the validation coefficients of the subjective methods.