Reproducibility and validity of a food-frequency questionnaire (NFFQ) to assess food consumption based on the NOVA classification in adults

NOVA is a classification that divides foods into four groups according to processing. Since no questionnaires have been validated assess the consumption of with different levels processing in general adult population, we tested reliability and validity 94-item Food Frequency Questionnaire (NFFQ) designed estimate intake (g/day) weight ratio (%) food Italian adults. Time were by administrating NFFQ 110 subjects on two occasions comparing it weighed dietary record (WDR). Strong correlations between NFFQs (r > 0.7, p < 0.001) intraclass correlation coefficients (ICC) 0.851–0.940 indicated good test-retest reliability. Moderate WDR (0.6<r 0.7), ICC 0.536–0.741, consistent agreement for percentages as revealed Bland-Altman plots moderate validity. The could be useful future investigations this research field.