FITS and KNHS Overview: Methodological Challenges in Dietary Intake Data Collection among Infants, Toddlers, and Children in Selected Countries.

The FITS (Feeding Infants and Toddlers Study) and KNHS (Kids Nutrition and Health Study) are large-scale cross-sectional surveys designed to explore eating patterns, nutrient intakes, and food sources of nutrients among infants and children. FITS and KNHS use data from national surveys when available, but when data are not available for age groups of interest, we collect data using similar methods. So far, we have applied a common analysis approach in Australia, China, Mexico, the Philippines, Russia, and the United States. Although dietary data collection methods shared similarities, other aspects of the survey methodology differed considerably. Food composition tables varied, limiting accurate intake estimates to a short list of nutrients in some countries. Age groups and food grouping systems were not consistent, and the level of detail varied. Not all surveys recorded details about the meals or times when foods were consumed. Nonetheless, the FITS and KNHS have standardized age categories and food groupings, so comparisons can be made, and we have imputed missing values to complete data sets for nutrients of interest. We have also supported primary data collection to fill gaps. This manuscript provides an overview of the individual studies and country data that comprise the current FITS and KNHS.