Bread Composition and Dietary Fibre Intake: Modelling Consumption Patterns and Substitution of White with Wholegrain Bread

Background/Objectives: Inadequate dietary fibre intake remains a public health concern across Europe, particularly for adolescents. Bread is a widely consumed staple and a potential vehicle for improving dietary fibre intake. This study aimed to quantify the dietary fibre content of commonly consumed breads and assess their contribution to daily dietary fibre intake in the Slovenian population, with a focus on adolescents. Methods: A total of 58 bread samples were analysed using an accredited enzymatic-gravimetric method. Consumption data were drawn from the nationally representative SI.Menu dietary survey. Results: A substantial variation in dietary fibre content was observed across bread types, with wholegrain breads providing the highest levels (mean: 7.5 g/100 g) and white wheat breads the lowest (2.9 g/100 g). In adolescents, white wheat bread was most often consumed, contributing disproportionately to total bread intake and limiting dietary fibre intake. We modelled two substitution scenarios, replacing 30% and 50% of white wheat bread with wholegrain bread, which resulted in mean dietary fibre increases of 1.4 g/day and 2.0 g/day, respectively. Conclusions: These findings demonstrate that realistic bread substitution strategies—particularly in institutional settings such as schools—could significantly improve dietary fibre intake in youth populations. The study also underscores the need for clearer regulatory definitions and labelling of wholegrain bread, especially in non-prepacked products.