Harmonizing dietary datasets for global surveillance: Methods and findings from the Global Dietary Database.

OBJECTIVE The Global Dietary Database (GDD) expanded its previous methods to harmonize and publicly disseminate individual-level dietary data from nutrition surveys worldwide. DESIGN Analysis of cross-sectional data. SETTING Global. PARTICIPANTS General population. METHODS Comprehensive methods to streamline the harmonization of primary, individual-level 24-hour recall and food record data worldwide were developed. To standardize the varying food descriptions, FoodEx2 was used, a highly detailed food classification and description system developed and adapted for international use by EFSA. Standardized processes were developed to: identify eligible surveys; contact data owners; screen surveys for inclusion; harmonize data structure, variable definition and unit, and food characterization; perform data checks; and publicly disseminate the harmonized datasets. The GDD joined forces with FAO and EFSA, given the shared goal of harmonizing individual-level dietary data worldwide. RESULTS Of 1,500 dietary surveys identified, 600 met the eligibility criteria, and 156 were prioritized and contacted; 55 surveys were included for harmonization and, ultimately, 52 were harmonized. The included surveys were primarily nationally representative (59%); included high- (39%), upper-middle (21%), lower-middle (27%), and low- (13%) income countries; usually collected multiple recalls/ records (64%); and largely captured both sexes, all ages, and both rural and urban areas. Surveys from low- and lower-middle vs high- and upper-middle income countries reported fewer nutrients (median 17 vs. 30), and rarely included nutrients relevant to diet-related chronic diseases, such as omega-3 fatty acids and sodium. CONCLUSIONS Diverse 24-hour recalls/records can be harmonized to provide highly granular, standardized data, supporting nutrition programming, research, and capacity development worldwide.