Reproducibility and Validity of a Nova-Based Food Frequency Questionnaire in Older Italian Adults: The NFFQ-Elderly

Background/Objectives: Nutritional research emphasizes evaluating food processing levels alongside nutrient content. The Nova system categorizes foods as minimally processed foods (MPFs), processed culinary ingredients (PCIs), processed foods (PFs), and ultra-processed foods (UPFs). High UPF consumption is linked to adverse health outcomes in older adults. Traditional Food Frequency Questionnaires (FFQs) often fail to capture processing differences. This study evaluated the reproducibility and relative validity of a Nova-based FFQ (NFFQ-Elderly) in Italian healthy older adults aged ≥65 years. Methods: A total of 111 older adults (73.7 ± 5.9 years; 56.8% women) completed the NFFQ-Elderly twice (4-6 weeks interval). Relative validity was compared with a three-day weighed food record. Foods were categorized by Nova groups and analyzed for absolute intake, energy and weight percentages. Pearson correlation (r), intraclass correlation coefficients (ICCs), and Bland-Altman plots were used. Results: Reproducibility was satisfactory for MPFs (r = 0.75; ICC = 0.74), UPFs (r = 0.87; ICC = 0.85), and PFs (r ≈ 0.73; ICC ≈ 0.66-0.67). Relative validity was moderate for MPFs (r = 0.57; ICC = 0.53) and UPFs (r = 0.48; ICC ≈ 0.37), but lower for PCIs. Accuracy generally improved when intakes were expressed as percentages of total energy or weight. Bland-Altman analyses showed limited mean bias for MPFs and PFs, but higher variability for PCIs and absolute energy intake. Conclusions: The NFFQ-Elderly appears to be a suitable tool for ranking older adults according to their relative intake of MPFs and UPFs. Estimates for PCIs are less reliable, indicating caution when interpreting absolute intake values.