Suppression of blood glucose level elevation and promotion of GLP-1 secretion by ingestion of Undaria pinnatifida sporophylls (Mekabu): Open-label crossover design

Abstract

Background: It has been confirmed that the daily consumption of seaweed such as Wakame (Undaria pinnatifida) and Kombu (Saccharina japonica) has an inhibitory effect on the rise in postprandial blood glucose levels. Similar effects can also be expected for Mekabu, which is Wakame sporophylls and contains large quantities of water-soluble dietary fiber. In this study, we examined the effects of preprandial intake of Mekabu on postprandial blood glucose levels and blood glucose regulation-related hormones in healthy young women.Methods: The subjects were ten healthy young adult women. Mekabu was eaten, followed by rice only. Blood was sampled five times: while fasting (0 min), and 15, 30, 90, and 120 minutes after eating. Measurements were taken of blood glucose level and blood glucose regulation-related hormones.Result: Eating Mekabu before rice resulted in a significant reduction of Δglucose and Δinsulin at 30 minutes after ingestion (p = 0.034, p = 0.049, respectively). The concentration of glucagon-like peptide-1 (GLP-1) in plasma was higher 30 minutes after eating (p = 0.044), 60 minutes (p = 0.0.31), and 120 minutes (p = 0.019) when Mekabu was eaten preprandially.Conclusions: In the present study, GLP-1 secretion was sustained by eating Mekabu, which is Wakame sporophylls, before rice. Our results suggest that ingesting Mekabu, which contains large amounts of viscous alginic acid, prior to a meal not only suppresses postprandial blood glucose level, but supports the extended secretion of GLP-1, providing a sustainable incretin effect.