Addition of Orange Pomace Attenuates the Acute Glycemic Response to Orange Juice in Healthy Adults

Background Fiber is an important part of a healthy diet and is known to attenuate postprandial glycemia. Orange pomace (OP) is a by-product of orange juice (OJ) production and is a rich source of fiber. Objective Two separate studies determined the impact of added OP to 100% OJ on postprandial glycemic response compared with sugar-matched OJ or whole orange fruit (WOF). Methods Study 1 included 17 adults [65% female, age 39.3 ± 3.1 y, and BMI (in kg/m2) 24.6 ± 0.7], and study 2 included 45 different adults (47% female, age 25.1 ± 4.3 y, and BMI 22.5 ± 1.6). Studies were conducted at separate locations using a randomized, 3-arm, crossover design to test the glycemic response to sugar-matched OJ, OJ with 5 g fiber from OP (OPF), or WOF. The primary outcomes were 2-h glucose incremental area under the curve (iAUC) in study 1, analyzed by repeated measures ANOVA, and maximum glucose concentration (Cmax) in study 2, analyzed using PROC MIXED (ANCOVA). Glucose and insulin concentrations were measured at fasting and multiple time points over 2 h after test product consumption (study 1, serum; study 2, plasma). Results In study 1, glucose iAUC was not significantly lower in OPF compared to the OJ or WOF (825 ± 132 compared with 920 ± 132 and 760 ± 132 mg · min · dL-1, respectively, P = 0.57 for both). In study 2, glucose iAUC was significantly lower in WOF compared with OPF and OJ (689 ± 70.7 compared with 892 ± 70.7 and 974 ± 70.7 mg · min · dL-1, P = 0.02 and 0.001, respectively). Data from both studies indicated OPF reduced Cmax compared with OJ and that the reductions were comparable to WOF (study 1: OPF, 115 ± 4.06 compared with OJ, 124 ± 4.06 and WOF, 114 ± 4.06 mg · dL-¹, P = 0.002 and 0.75, respectively; study 2: OPF, 128 ± 1.92 compared with OJ, 136 ± 1.92 and WOF, 125 ± 1.92 mg · dL-¹, P = 0.001 and 0.28, respectively). Conclusion Data from both studies demonstrated no significant effect of OPF on postprandial iAUC compared with OJ. However, adding OP into OJ attenuates the postprandial glucose Cmax, and the responses were comparable to WOF in healthy adults.