Beta-Glucan from Two Sources of Oat Concentrates Affect Postprandial Glycemia in Relation to the Level of Viscosity

@article{citeulike:2214613, abstract = {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 -glucan from oats (aqueous vs. enzymatic) in relation to the level of viscosity of -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/m2) were randomly assigned, on three separate occasions, to consume one of three fiber-matched treatments along with a 75g oral glucose drink. The enzymatically processed -glucan (Oat-A) differed from -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 -glucan through enzymatic, rather than by aqueous methods, preserves the viscosity and improves postprandial glycemic control.}, author = {Panahi, Shirin and Ezatagha, Adish and Temelli, Feral and Vasanthan, Thavaratnam and Vuksan, Vladimir }, citeulike-article-id = {2214613}, comment = {It has been repeatedly demonstrated that daily consumption of soluble dietary fiber can significantly reduce the risk of type 2 diabetes and cardiovascular disease [1]. This is due in part to the ability of fiber to reduce postprandial glycemia and improve long-term glycemic control [2,3]. It is hypothesized that the rheological properties of soluble dietary fiber are highly related to its effects on glucose control [4]. For instance, the ability of oat-derived β-glucan to reduce postprandial glycemia has been strongly correlated with its viscosity [5], demonstrating an inverse linear relationship between the logarithm of viscosity measures and peak postprandial plasma glucose and insulin responses after consuming various doses of purified oat β-glucan with a 50g oral glucose load. Despite these findings, the levels of viscosity required to achieve specific glucose-lowering effects are poorly understood. Still, the majority of trials investigating dietary fiber have not accounted for the principles of polysaccharide solubility and viscosity as the main determinants of its physiological outcome. While a small number of studies have shown the inter-fiber variability in viscosity [3], none have compared the intra-fiber variability or the differences in viscosity within the same type of fiber. In order to increase the physiological effectiveness of oat β-glucan concentrates, a unique technology has been developed to increase their β-glucan content while maintaining its native molecular weight and thus, viscosity. The current study investigated oat β-glucan concentrates produced by two processing methods: the first is an aqueous process conventionally used to extract β-glucan by solubilizing it in large quantities of water; the second is a novel process which is an alcohol-based enzymatic technique used to concentrate the native cell walls containing the β-glucan. While the aim of both procedures is to remove the starch and protein components of the oats, the second process aims to obtain a fiber concentrate of high viscosity by preserving the native state of β-glucan, whereas the β-glucan can be degraded upon solubilization in the first process due to high shear and endogenous enzyme activity. }, journal = {J Am Coll Nutr}, keywords = {diet, dietaryfiber, glycemiapp}, month = {December}, number = {6}, pages = {639--644}, posted-at = {2008-01-10 14:41:37}, priority = {2}, title = {Beta-Glucan from Two Sources of Oat Concentrates Affect Postprandial Glycemia in Relation to the Level of Viscosity}, url = {http://www.jacn.org/cgi/content/abstract/26/6/639}, volume = {26}, year = {2007} }

TY - JOUR ID - citeulike:2214613 L3 - citeulike-article-id:2214613 TI - Beta-Glucan from Two Sources of Oat Concentrates Affect Postprandial Glycemia in Relation to the Level of Viscosity JF - J Am Coll Nutr VL - 26 IS - 6 SP - 639 EP - 644 N2 - 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 -glucan from oats (aqueous vs. enzymatic) in relation to the level of viscosity of -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/m2) were randomly assigned, on three separate occasions, to consume one of three fiber-matched treatments along with a 75g oral glucose drink. The enzymatically processed -glucan (Oat-A) differed from -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 -glucan through enzymatic, rather than by aqueous methods, preserves the viscosity and improves postprandial glycemic control. KW - diet KW - dietaryfiber KW - glycemiapp N1 - It has been repeatedly demonstrated that daily consumption of soluble dietary fiber can significantly reduce the risk of type 2 diabetes and cardiovascular disease [1]. This is due in part to the ability of fiber to reduce postprandial glycemia and improve long-term glycemic control [2,3]. It is hypothesized that the rheological properties of soluble dietary fiber are highly related to its effects on glucose control [4]. For instance, the ability of oat-derived β-glucan to reduce postprandial glycemia has been strongly correlated with its viscosity [5], demonstrating an inverse linear relationship between the logarithm of viscosity measures and peak postprandial plasma glucose and insulin responses after consuming various doses of purified oat β-glucan with a 50g oral glucose load. Despite these findings, the levels of viscosity required to achieve specific glucose-lowering effects are poorly understood. Still, the majority of trials investigating dietary fiber have not accounted for the principles of polysaccharide solubility and viscosity as the main determinants of its physiological outcome. While a small number of studies have shown the inter-fiber variability in viscosity [3], none have compared the intra-fiber variability or the differences in viscosity within the same type of fiber. In order to increase the physiological effectiveness of oat β-glucan concentrates, a unique technology has been developed to increase their β-glucan content while maintaining its native molecular weight and thus, viscosity. The current study investigated oat β-glucan concentrates produced by two processing methods: the first is an aqueous process conventionally used to extract β-glucan by solubilizing it in large quantities of water; the second is a novel process which is an alcohol-based enzymatic technique used to concentrate the native cell walls containing the β-glucan. While the aim of both procedures is to remove the starch and protein components of the oats, the second process aims to obtain a fiber concentrate of high viscosity by preserving the native state of β-glucan, whereas the β-glucan can be degraded upon solubilization in the first process due to high shear and endogenous enzyme activity. AU - Panahi, Shirin AU - Ezatagha, Adish AU - Temelli, Feral AU - Vasanthan, Thavaratnam AU - Vuksan, Vladimir PY - 2007/12/01/ UR - http://www.jacn.org/cgi/content/abstract/26/6/639 ER -