Consumers' knowledge of healthy diets and its correlation with dietary behaviour

Background: Procedural nutrition knowledge is knowledge of how to eat a healthy diet. This type of knowledge potentially plays an important role in dietary behaviour. Previous studies of consumers' nutrition knowledge did not systematically assess procedural nutrition knowledge. Thus, we administered a survey of procedural nutrition knowledge to Swiss consumers to assess the prevalence of misconceptions about healthy eating. Methods: We developed 13 procedural nutrition knowledge items. Nine items were based on qualitative consumer interviews and four items were derived from expert guidelines. The items had a true/false format. We administered the items to a random population sample in a written postal survey (n = 1,043). The survey also assessed the consumers' self-reported food consumption. For each respondent, we computed the number of correctly answered knowledge items and we correlated this number with food consumption frequencies. Results: The procedural nutrition knowledge items received between 3% and 38% incorrect answers. Individuals with a higher number of correctly answered items consumed more vegetables (r = 0.29). Higher knowledge was associated with the female gender, younger age, higher education, nutrition-related qualifications and not being on a diet (P < 0.001). Conclusions: Our findings indicate that misconceptions exist in the general population about healthy eating. These misconceptions are associated with a decreased consumption of foods usually defined as healthy. Some population sub-groups seem particularly susceptible to holding such misconceptions. The implications for nutrition education, particularly concerning the role of fruit and vegetable consumption as well as the food pyramid are discussed.