Effect of Oak Flour on Glycemic Index and Satiety Index of White Bread

Background: Low Glycemic Index (GI) and high Satiety Index (SI) foods have been associated with the decreased risk of chronic diseases and obesity. Objectives: The present study examined the effect of oak flour on GI, Glycemic Load (GL), and SI of white bread. Methods: This randomized crossover trial was conducted at Ahvaz University of Medical Sciences, Ahvaz, Iran, during the year 2017. To determine the GI, 10 healthy subjects consumed three bread types (white bread, bread containing 25% oak flour, and bread containing 50% oak flour) and reference food (glucose) containing 50 g of carbohydrates on separate occasions. Finger-prick blood samples were collected at fasting (0 min) and at 15, 30, 45, 60, 90, and 120 min after meal consumption. To determine the SI, 20 healthy individuals consumed 240 kcal portions of test bread types (white bread, bread containing 25% oak flour, and bread containing 50% oak flour) on separate occasions. The satiety ratings were collected at fasting and every 15 min for over 2 h after food ingestion to evaluate the SI. Results: There were no significant differences in the mean of blood glucose Incremental Areas Under the Curve (IAUC) between the test bread types (white bread: 2,883.2 ± 353.7 vs. 25% oak flour bread: 3,163.1 ± 214.7 vs. 50% oak flour bread: 3,245.1 ± 255.9) (P > 0.05). Also, no significant differences were observed between the mean of bread GIs (P > 0.05). The satiety IAUCs of both oak bread types (25% oak flour bread: 377.17 ± 59.83, 50% oak flour bread: 427.87 ± 55.46) were significantly greater than that of white bread (248.55 ± 46.45) (P < 0.001). The SI of both oak bread samples (25% oak flour bread: 202.48 ± 7.92, 50% oak flour bread: 266.25 ± 11.66) was significantly greater than that of white bread (100) (P < 0.001). Conclusions: The addition of oak flour did not modify the GI; however, it increased the SI of white bread and created a greater feeling of satiety.