In a previous study, we found that a raw Mekabu (Undaria pinnatifida sporophylls) diet stimulated and sustained GLP-1 secretion as well as suppressed postprandial blood glucose levels. Mekabu contains soluble dietary fibers, alginic acid and fucoidan. Therefore, we aimed to investigate whether alginic acid and fucoidan in Mekabu are involved in sustained postprandial GLP-1 secretion. Each of eight young women participated in the following experiment processes, that is (1) being fed with rice alone, (2) ingesting alginate 10 minutes before being fed with rice, and (3) ingesting fucoidan 10 minutes before being fed with rice. After each of these processes, changes in the level of their blood glucose, insulin, and GLP-1 were measured and compared over time to prove the effect of alginate and fucoidan. Alginic acid intake tended to contribute to sustained secretion of GLP-1, although there was no significant difference in blood glucose and GLP-1 compared to the white rice group. However, which of the components in Mekabu is particularly involved in the suppression of postprandial blood glucose elevation and the sustained secretion of GLP-1 requires further investigation.

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