High-glycaemic foods contribute to elevated risk of obesity, type 2 diabetes, and cardiometabolic disease. Replacing digestible carbohydrates with dietary fibres is known to reduce postprandial glycaemic excursions, enhance satiety, and support beneficial microbial fermentation. However, limited evidence exists on how interactions between different isolated fibres within a processed food matrix may modulate these responses, particularly when such interactions could recreate structural features of intrinsic plant fibre networks that naturally restrict starch accessibility and alter fermentation dynamics. This randomized, single-blinded, placebo-controlled crossover trial will investigate how isolated dietary fibres, alone and in combination, influence metabolic and microbial responses when incorporated into a commonly consumed cereal-based food (scone). Overweight but otherwise healthy adults (BMI 25-\<30 kg/m²) will consume seven fibre-enriched scone formulations across two consecutive mornings per intervention phase. Outcomes include postprandial glycaemic response measured via continuous glucose monitoring (primary outcome), perceived satiety and energy intake, gastrointestinal symptoms, fermentation dynamics via breath hydrogen and methane, and gut microbiota composition assessed through 16S rRNA sequencing. This study will generate novel insights into potential synergistic interactions between isolated fibres within a food matrix and their consequences for glycaemic control, satiety, microbial fermentation, and community. Findings will inform next-generation food design strategies aimed at replicating complex intrinsic fibre structures to enhance the health impact of processed foods.
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Impact on Postprandial Glycaemic Response
Timeframe: Measured continuously over each 2-day intervention phase, with readings recorded every 15 minutes, covering all seven scone interventions plus baseline across the 28-day study period.