Characterization of the Impact of Dietary Fibre Interactions in Food Products on Postprandial Glycaemic Response, Satiety, and Microbiome Composition and Function
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.
• Be willing and able to give written informed consent.
• Be between 18 and 45 years of age.
• Have a BMI of =25\<30kg/m2(overweight).
• Have a waist circumference of \>94cm for a male, \>80cm for a female (increased risk of metabolic syndrome).
• Have had a stable body weight (\<5% change over the past three months).
• Be in general good health as determined by the investigator through interview and vital signs (blood pressure, pulse, temperature). Systolic blood pressure less than 160mm Hg and diastolic blood pressure less than 100 mm Hg (defined as Hypertension stage 2).
• Be willing to avoid consuming dietary supplements (at the discretion of the investigator), prebiotics, probiotics, or fibre-rich supplements within four weeks before the baseline visit, and until the end of the study.
• Be willing to avoid vigorous physical activities on the interventional days (defined as any physical activity that is planned to achieve a fitness goal).
• Be willing to consume the investigational food products and menu plan daily for the duration of the study.