Substitution of Corn Starch with Resistant Starch Type 4 in a Breakfast Bar Decreases Postprandial Glucose and Insulin Responses: A Randomized, Controlled, Crossover Study

BACKGROUND: Resistant starches type 4 (RS4) are chemically modified starches that are resistant to digestion by human enzymes. OBJECTIVE: We aimed to test our hypothesis that replacement of standard starch with RS4 in a baked breakfast bar would decrease postprandial glycemic and insulinemic responses in healthy adults. METHODS: In this double-blind, randomized crossover study, 21 healthy adults [10 men; 20–45 y old; BMI (kg/m(2)): 19.3–27.0] consumed a baked breakfast bar containing tapioca-based RS4 (Actistar 75330; Cargill, Inc.) or a macronutrient-matched control bar, delivering 32 g and 4 g of dietary fiber, respectively. Primary outcome was the incremental area under the curve (iAUC(0–120 min)) for postprandial capillary glucose. Other outcomes included postprandial serum insulin iAUC(0–120 min), glucose and insulin maximum concentration (C(max)), and time to C(max) (T(max)). RESULTS: Median glucose iAUC(0–120 min) was 22% lower (P < 0.05) and median insulin iAUC(0–120 min) was 37% lower (P < 0.05) after consumption of the RS4 food compared with the control food. Glucose and insulin C(max) and T(max) were not significantly different (P > 0.05) between foods. CONCLUSION: The results suggest that replacement of standard starch with tapioca-based RS4 is a practical approach for reducing available carbohydrate in products and achieving postprandial blood glucose management. This trial was registered at clinicaltrials.gov as NCT03239288.