Reproducibility and relative validity of a semi-quantitative food-frequency questionnaire in an adult population of Rosario, Argentina

Introduction: Dietary assessment of nutrients and food groups by food frequency questionnaire needs to be validated in each population. The objective of this cross-sectional study was to evaluate the reproducibility and relative validity of a semi-quantitative food frequency questionnaire among adults of Rosario, Argentina.Material and Methods: Two food frequency questionnaires and four 24-hour dietary recalls were applied in a sample of 88 adults. Reproducibility of food frequency questionnaire was estimated by correlation coefficients, and validity was assessed comparing the second food frequency questionnaire and the average of the 24-hour dietary recalls using cross-classification and Bland–Altman analyses.Results: Pearson and intraclass correlation coefficients showed higher correlation for food groups than for energy and nutrients. More than 65% of the subjects were classified into the same quintile or into the adjacent quintile by both food frequency questionnaires. Bland–Altman plots showed reasonably acceptable agreement between the second food frequency questionnaire and 24-hour dietary recalls, especially for the main Argentinian foods groups (meat, cereal, dairy products, vegetables and fruits).Conclusions: Overall, food frequency questionnaire showed acceptable reproducibility and relative validity for assessment main food groups and nutrient intakes for adult population in Rosario.