(P20-061-25) Impact of a Diet in Which Digestible Carbohydrates Are Systematically Substituted With Isolated Dietary Fibers on Glycemia, Satiety, Energy Intake and the Gut Microbiome

Objectives: Food reformulation in which dietary fibers (DF) replace digestible carbohydrates can decrease the energy density and glycemic index of starch-based foods while providing substrates for gut microbial metabolism. However, it is unclear whether reformulated fiber rich (RFR) foods contribute to metabolic improvements and a reduction in energy intake when incorporated into a daily diet. This randomized controlled trial aimed to investigate the impact of a whole diet incorporating RFR foods on glycemia, energy intake, satiety and gut microbiome composition and function.

Methods: The Fiber Full Study was a randomized, single-blinded, crossover-controlled trial. Twenty-four adults (22-45 years) with excess body weight (BMI 25-35 kg/m²) were randomized to either a RFR or control diet for an 8-day period. Adopting a whole diet approach that provides and assesses all meals and snacks, participants on the RFR diet began on a lower fiber dose (38-45 g/day) which increased (57-67 g/day) for four days each verses a control diet (21-25 g fiber/day). A minimum washout period of 13-days followed before crossover to the alternate intervention. RFR foods (bread, pasta and scones) were engineered so that refined carbohydrates were systematically replaced with isolated DF. Outcomes included: continuous glucose concentration, energy intake, satiety, gastrointestinal tolerability, product acceptability and gut microbiome composition and function.

Results: Twenty-two participants completed the study. High adherance was observed on both interventions with participants consuming on average < 100 kcal/day of non-study foods. No significant difference (p>0.05) was noted in the hedonic acceptability of the scone and pasta formulations between treatments. Study diets were well tolerated with no significant difference in the frequency of bowel movements or flatus between treatments. Analyzes on glycemia, satiety, energy intake and the fecal microbiome are ongoing.

Conclusions: These findings highlight the feasibility to deliver around 60 grams of DF per day at the expense of digestible carbohydrates in foods that are palatable and well tolerated. Upon completion of analyzes this study aims to determine the tangible value of food reformulation to benefit human metabolic health and energy control.

Funding Sources: Research Ireland