A scale to assess teachers' dietary knowledge by the Brazilian Dietary Guidelines

This psychometric study adapted and validated a scale to assess teachers' knowledge of healthy eating. After selecting an instrument (GAB1), its wording was adapted to the school environment and the clarity, importance and relevance of the 16 statements were assessed. Teachers' responses to the adapted questionnaire were analysed using a three-parameter logistic model based on Item Response Theory. Assessment of parameters for retaining or excluding statements from the scale was followed by analysis of fit. Levels of interpretation of the scale were proposed and descriptive analyses were carried out to characterise the teachers. The statements presented satisfactory clarity, importance and relevance. After analysing the teachers' responses, the final 10-item model returned adequate goodness-of-fit (RMSEA = 0.012; SRMSR = 0.042; TLI = 0.99 and CFI = 0.99). Three levels of knowledge were identified: food choice; from food to meals; and food and nutrition education. Teachers who worked in schools where healthy eating was included in programme content were more knowledgeable. The GAB1-professores scale contributes to planning and evaluating teacher qualification processes.