Submitted to: UJNR Food & Agricultural Panel Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 14, 2005
Publication Date: October 21, 2005
Citation: Behall, K.M. 2005. Benefits of soluble fiber from barley on glycemic parameters. UJNR Food & Agricultural Panel Proceedings. Interpretive Summary: Diabetes, obesity and the metabolic syndrome are major health problems in the United States. Consumption of soluble fiber has been reported to have beneficial health effects, especially the reduction of blood glucose and insulin after a meal containing soluble fiber. Consumption of starches that resist digestion in the upper intestine reduces blood glucose and insulin after a meal containing the resistant starch. Two studies carried out at the Beltsville Human Study Facility investigated whether the beneficial effects of soluble fiber and resistant starch on glucose and insulin response after a meal are additive. Twenty normal-weight (BMI: 22.0, women; 23.8, men) and 20 overweight (BMI: 30.4, women; 29.0, men) subjects were given 10 meals in a random order. Meals included glucose alone and 9 muffins made with three levels of starch that resists digestion in the small intestine and 3 levels of soluble fiber (beta glucan). To maintain similar normal blood glucose levels, men and women who were overweight needed higher plasma insulin levels after the meals than the normal-weight subjects did. The amount of glucose and insulin found in blood after a meal decreased as the amount of resistant starch and beta-glucan increased. The greatest reduction in summed glucose (28% and 33% lower for women and men, respectively) and insulin (49% and 39.6% lower for women and men, respectively) occurred after meals containing the highest amounts of beta-glucan and resistant starch. Soluble fiber appears to have a greater effect on glucose and insulin postprandial response than does resistant starch. The reduction in glycemic response was moderately enhanced by combining resistant starch and soluble fiber. These results indicate that both soluble fiber and resistant starch are an effective addition to a healthy diet to lower blood glucose and insulin after a meal. This information is important to the general public and to health care workers planning diets for individuals with type 2 diabetes or the metabolic syndrome since it increases the number of grains that can be consumed for beneficial reduction of blood glucose and insulin levels.
Technical Abstract: Previous studies conducted at Beltsville Human Nutrition Research Center found consumption of a meal high in resistant starch or soluble fiber (beta-glucan) decreases peak insulin and glucose concentrations and area under the curve (AUC). The objective of these studies was to determine whether the effects of soluble fiber and resistant starch (RS) on glycemic variables are additive. Twenty normal-weight (BMI: 22.0, women; 23.8, men) and 20 overweight (BMI: 30.4, women; 29.0, men) subjects were given 10 tolerance tests in a Latin square design: glucose alone (75 g glucose) and 9 muffins (75 g available carbohydrate) made with three levels of RS(averaging 0.6, 5.7, and 9.5 g/100 g dry weight) and 3 levels of soluble fiber (0.2, 2.2, and 4.2 g/100 g dry weight). A standard menu was fed for 3 d. Overweight subjects responded with plasma insulin concentrations higher than those of normal-weight subjects to maintain similar plasma glucose levels. Glucose and insulin responses decreased with increasing RS and beta-glucan content. The greatest AUC reduction occurred after meals containing high beta-glucan and high resistant starch; glucose AUC was 28% and 33% lower for women and men, respectively, and insulin AUC was 49% and 39.6% lower, respectively. Soluble fiber appears to have a greater effect on glucose and insulin postprandial response than does resistant starch. The reduction in glycemic response was minimally enhanced by combining RS and soluble fiber.