SUPPRESSION OF POSTPRANDIAL HYPERGLYCEMIA BY BUCKWHEAT ALBUMIN

• Published in: Annals of nutrition and metabolism 2017-10, Vol.71 (Suppl. 2), p.381
• Main Authors: Kumagai, Hitomi, Yamaguchi, Yusuke, Ninomiya, Kazumi, Ina, Shigenobu, Akao, Makoto, Kumagai, Hitoshi
• Format: Article
• Language: English
• Subjects: Albumin; Ammonium; Amylases; Blood; Blood glucose; Buckwheat; Carbohydrates; Diabetes; Diabetes mellitus; Diabetes mellitus (non-insulin dependent); Digestive enzymes; Food intake; Gel filtration; Glucose; Hyperglycemia; Insulin; Nutrition; Pancreas; Peptides; Proteins; Saliva; Starch; Sulfates; Wheat; α-Amylase
• ISSN: 0250-6807; 1421-9697
• DOI: 10.1159/000480486

Background and objectives: Diabetes mellitus is a disorder of blood glucose regulation. Most of the patients are categorized into type 2 that shows a symptom of insulin resistance and/or deficiency. For the prevention of type 2 diabetes, it is important to control the postprandial blood glucose level by an appropriate food intake. The retardation of starch hydrolysis by inhibiting the α-amylase activity is one of the effective ways to suppress the elevation in blood glucose level. Wheat α-amylase inhibitor possesses the inhibitory activity against α-amylase and suppresses postprandial hyperglycemia after starch administration. It has been used as a functional component in Food for Specified Health Uses (FoSHU) in Japan. We have already reported that rice albumin is indigestible and effectively suppresses the elevation in blood glucose level not only after starch administration but also after glucose administration. However, the effect of other cereal protein on hyperglycemia has not been fully examined yet. Therefore, the present study was conducted to examine if buckwheat protein could suppress postprandial hyperglycemia. Methods: Albumin was purified from buckwheat by ammonium-sulfate precipitation and gel filtration. First, the inhibitory activity of buckwheat albumin against α-amylase from human saliva, porcine pancreas and mealworm was evaluated in vitro. Next, rats were administered starch with and without the addition of buckwheat albumin. After the administration, the blood was collected from the tail vein at certain intervals. Then, the blood glucose level and the plasma insulin level were measured. Results: Buckwheat albumin inhibited the activity of α-amylase from porcine pancreas and mealworm, but did not inhibit that of α-amylase from human saliva. Although buckwheat albumin was hydrolyzed by digestive enzymes, it suppressed the elevation in blood glucose level after carbohydrate administration. The plasma insulin level was also suppressed by the administration of buckwheat albumin. Conclusions: Buckwheat albumin suppressed postprandial hyperglycemia in vivo though it was digestible indicating that peptides in the hydrolysate maintained the inhibitory activity against α-amylase even after digestion.