Objective: Soluble dietary fiber has been shown to attenuate the postprandial rise in blood glucose levels and reduce the risk of type 2 diabetes and cardiovascular disease. This effect seems to be related to its rheological properties including viscosity. We examined the intra-fiber variability between two different processing methods of concentrating beta-glucan from oats (aqueous vs. enzymatic) in relation to the level of viscosity of beta-glucan and its effect on postprandial glycemia in healthy individuals.
Design: In an acute, randomized, double-blind, crossover study, 11 healthy subjects (gender: 5M:6F; age: 34 +/- 5 years; BMI: 23 +/- 0.8 kg/m(2)) were randomly assigned, on three separate occasions, to consume one of three fiber-matched treatments along with a 75 g oral glucose drink. The enzymatically processed beta-glucan (Oat-A) differed from beta-glucan processed through the aqueous method (Oat-B) solely with regard to viscosity. Finger-prick capillary blood samples were obtained at fasting and at 15, 30, 45, 60, 90 and 120 min after the start of the test drink. The viscosities of the fiber drinks were determined (Paar Physica UDS200 viscometer).
Results: Rheological measurements demonstrated that Oat-A had a significantly higher viscosity than Oat-B and control at 5, 15, 30, 60, and 120 min (p < 0.001). The incremental area under the glucose curve (AUC) on Oat-A was 19.6% and 17% lower than that of Oat-B and control, respectively (p < 0.01).
Conclusions: This study shows that processing oat beta-glucan through enzymatic, rather than by aqueous methods, preserves the viscosity and improves postprandial glycemic control.