Glycemic and Insulinemic Response to a Commercial Food Bar Containing a Whey Protein Blend with Isomalto-oligosaccharides Plant Fiber as the Carbohydrate Source
T Grubic1, R Sowinski1, R Dalton1, C Favot1, B Sanchez1, PB Collins1, A Reyes1, C Rasmussen1, M Greenwood1, CP Earnest1,2, RB Kreider1
1Exercise & Sport Nutrition Lab, Human Clinical Research Facility, Texas A&M University, College Station, TX, USA
2Nutrabolt, Bryan, TX, USA
Background
This study examined the pharmacokinetic glucose and insulin response of a commercial Food Bar (Bar, Fitjoy™) containing a whey protein blend (20g), carbohydrate (25g) as isomalto-oligosaccharides plant fiber (VitaFiber™; 13 g fiber, 4 g sugar) fat (7g total, 1.5g saturated) (220 kcals) vs. 25 g of dextrose (96 kcals) placebo (PLA).
Methods
Twenty apparently healthy participants (50% female; BMI <24.9 kg/m2) participated in an un-blinded, randomized, cross-over trial. Participants donated a 10-h fasted blood sample prior to ingestion of their respective treatments. Additional blood samples were taken at 10, 20, 30, 60, 90, 120 and 240-min post-ingestion. Glucose and Insulin AUC were analyzed via a univariate general linear model (GLM) for treatment, treatment order, adjusted for sex and respective 0-min measures of glucose and insulin, as no sex- by-treatment effects were observed. A repeated measure GLM with the same adjustments was used to assess individual time point blood values. Data are mean ± SD, mean change (95% CI) and effect sizes as partial eta-squared (n2, 0.01 = small, 0.06 = medium, 0.13 = large).
Results
Glucose AUC was significantly greater following PLA (688±78 mmol-h/L) compared to Bar ingestion (599±50 mmol-h/L, n2, 0.08, P=0.001). No significant differences were observed between treatments for insulin AUC (PLA 1848±971; Bar 2136±1073 pmol-h/L, n2 = 0.14, P=0.38). Both groups demonstrated peak glucose concentrations at 30-min with significantly higher peak glucose values observed with PLA (PLA 7.51±1.24; Bar 5.61±0.62 mmol/L, P=0.001). At glucose peak, the Bar (5.61 mmol-h/L) was 25.3% lower than the PLA (7.51 mmol-h/L). For insulin, both groups demonstrated similar peak insulin concentrations at 30-min (PLA 27.83±15.17; Bar 30.87±20.68 pmol/L) with no differences between treatments. The insulin:glucose ratio was significantly lower at 30-min [PLA (3.65, 95% CI, 2.47, 4.82) vs. Bar (5.33, 95% CI, 4.15, 6.50)] and 60-min [PLA (2.69, 95% CI, 1.74, 3.65) vs. Bar (4.11, 95% CI, 3.16, 5.07)].
Conclusions
The estimated glycemic load of the Bar examined in this study ranges from 3.84-8.39 and exhibits a 25.3% lower glycemic response, but similar insulin response, compared to a dextrose PLA.
Acknowledgments
This study was supported by Nutrabolt (Bryan, TX) through an unrestricted research grant provided to Texas A&M University. CP Earnest serves as a Director of Clinical Sciences for Nutrabolt. RB Kreider serves as a university approved scientific advisor for Nutrabolt. PS Murano serves as quality assurance supervisor.