The concept of food literacy is evolving and expanding, increasing the need for a comprehensive measurement tool for food literacy. This study aimed to develop a validated food literacy questionnaire based on an expanded conceptual framework for food literacy. A literature review of existing frameworks and questionnaires for food literacy and focus group interviews (n = 12) were conducted to develop a conceptual framework and candidate questions. A Delphi study (n = 15) and pilot survey (n = 10) to test the preliminary questionnaire’s content and face validity were conducted, which were followed by the main survey (n = 200). Construct validity and reliability were assessed using exploratory factor analysis (EFA) and Cronbach’s alpha, respectively. Criterion validity was assessed by comparing food literacy scores with food knowledge scores (FN-score) and nutrient quotient scores (NQ-score). By integrating and revising the six existing conceptual frameworks and focus group interview results, we proposed a two-dimensional conceptual framework comprising a literacy dimension and a food system dimension. After reviewing 560 items and categorizing them into 18 domains (3 in the literacy dimension × 6 in the food system dimension), 32 questions were selected. As a result of the Delphi study, two items were deleted, and content validity was confirmed for the remaining 30 items (content validity ratio (CVR) = 0.92). Ten items were revised during the face validation process, and five items were excluded as a result of the EFA. The final food literacy questionnaire comprised 25 questions related to five factors: production, selection, preparation and cooking, intake, and disposal. Food literacy scores were positively associated with FN- and NQ-scores, confirming the reliability and criterion validity of the final questionnaire. The two-dimensional food literacy conceptual framework developed in this study systematically encompasses complex food literacy concepts by adding a food systems dimension (production, selection, preparation and cooking, intake, and disposal domain) to the existing literacy dimension (functional, interactive, and critical literacy domain). Based on this integrated conceptual framework, a 25-item food literacy questionnaire was developed and validated for practical use.

Food literacy refers to the knowledge, skills, and attitudes required for individuals to choose foods that promote health. As the rate of diet-related diseases increases, food literacy is becoming more important. However, there are no tools available to evaluate food literacy among the Korean elderly. We derived 547 questions from a literature review and, after three rounds of Delphi surveys, selected 33 preliminary questions. We calculated the content validity ratio of the questions and applied a face validity procedure. We then selected 32 questions, assessed their validity, and distributed them as a questionnaire to 205 elderly people. We then conducted exploratory factor analysis (EFA) to determine the validity of the questionnaire and used an internal consistency index (Cronbach’s α coefficient) to determine reliability. Based on the factor analysis, 13 questions were selected, distributed among three factors, and evaluated using the Kaiser–Meyer–Olkin (KMO) and Bartlett sphericity tests. The factor analysis showed that KMO was 0.872, which is a highly acceptable score, and the Bartlett sphericity test was χ² = 1,374.69 at p = 0.00. The food literacy questionnaire developed in this study will likely be helpful for improving the healthcare of elderly people.