Description and performance of two diet quality scores based on the Nova classification

To describe two low-burden diet quality scores and evaluate their performance in reflecting the dietary share of the least and most processed foods defined within the Nova food system classification.

This cross-sectional study included data from the NutriNet-Brasil cohort. Participants answered the Nova24hScreener, a 3-minute self-administered questionnaire measuring the consumption of a set of foods on the day before. Food items included in this tool belong to two main groups of the Nova classification: unprocessed or minimally processed whole plant foods (WPF, 33 items) and ultra-processed foods (UPF, 23 items). Two scores were obtained by summing the number of items checked: the Nova-WPF and the Nova-UPF. We compared the scores, respectively, with the dietary intake (% of total energy) of all unprocessed or minimally processed whole plant foods and all ultra-processed foods obtained from a full self-administered web-based 24-hour recall performed on the same day.

The approximate quintiles of each score had a direct and linear relationship with the corresponding % of energy intake (p-value for linear trend < 0.001). We found a substantial agreement between the intervals of each score and the corresponding % of energy intake (Nova-WPF score: Prevalence-Adjusted and Bias-Adjusted Kappa (PABAK) 0.72, 95%CI 0.64-0.81; Nova-UPF score: PABAK 0.79, 95%CI 0.69-0.88).

These two scores performed well against the dietary share of unprocessed or minimally processed whole plant foods and ultra-processed foods in Brazil and can be used to evaluate and monitor diet quality.