Influence of Proprietary White Kidney Bean Protein on Human Postprandial Glucose Response

Background: Elevated concentrations of blood glucose following intake of soluble starch are partly responsible forthe tissue and organ damage associated with diabetes and metabolic syndrome. A dietary supplement that lowersthe glycemic response to other starchy foods would provide diabetic patients with a wider variety of foods in theirdiet. Objective: This project tested the hypothesis that white kidney bean protein lowers the peak blood glucoseconcentration and the overall glycemic response to consumption of a fixed amount of carbohydrate. Methods: Glycemic response to white bread eaten with the bean protein or a placebo control protein was measured.Glucose in interstitial fluid was recorded with a continuous glucose monitoring (CGM) system calibrated to capillaryblood glucose samples measured by glucometer. After an overnight fast, healthy male and female subjects (N=12,age=27±13yr, BMI 22±2.4) consumed 1.1 g of protein from non-fat dry milk powder as placebo (Treatment 1) or awhite kidney bean protein powder (Treatment 2) suspended in 250 mL water, followed by two slices of white breadthat supplied 50 g of non-fiber carbohydrate. The procedure was repeated for 3 days for each beverage powder, in ablinded, random order. Incremental area under the curve (iAUC) for interstitial glucose concentration was calculatedfrom the CGM data and the positive values from the first rise and fall of the glucose were summed to calculate theaggregate iAUC for each subject on each day. Results: Significant differences were observed between the 2 treatments (P<0.005) and among different subjects(P<0.0001) for iAUC. Mean glycemic iAUC response for the placebo beverage (dilute milk) was an increase of 2209mg*min/dL and for the white kidney bean protein beverage the increase was 1625 mg*min/dL, or 26.4% less.Although 3 subjects had a non-significantly higher glycemic response to the bean protein beverage, 9 subjects hadhigher glycemic response to the placebo treatment. Conclusion: The data support the hypothesis that white kidney bean protein consumed with a carbohydrate mealmay lower the peak blood glucose concentration that results from starch digestion and absorption.