Effect of Powdered Morus australis Leaves on Arterial Stiffness Response after Sucrose Ingestion in Healthy Young Men: A Pilot Study

Acute arterial stiffening occurs during postprandial hyperglycemia. Such vascular responses are suggested to be averted by suppressing the postprandial glycemic response. We previously developed an α-glucosidase-inhibiting tea powder from the leaves of Morus australis (M. australis), a mulberry species distributed in the Ryukyu Islands, and demonstrated that this powder has an inhibitory effect on blood glucose elevation after sucrose ingestion. This study aimed to investigate the effect of powdered M. australis leaf intake on the arterial stiffness response after sucrose ingestion. In a randomized crossover design, 12 healthy young men completed two trials: with (mulberry [M] trial) and without (control [C] trial) intake of powdered M. australis leaves before ingestion of 75 g of sucrose. Blood glucose levels and brachial-ankle pulse wave velocity (baPWV), an index of systemic arterial stiffness, were measured at baseline and 30, 60, and 120 min after ingestion. Both trials caused a significant increase in blood glucose levels at 30 and 60 min after ingestion, with significantly lower values at 30 min after ingestion in the M trial than in the C trial. baPWV significantly increased at 60 min after ingestion in the C trial, but not in the M trial. These findings demonstrate that prior ingestion of powdered M. australis leaves can prevent the transient arterial stiffening after sucrose ingestion in healthy young men.

Effects of super-hard rice bread blended with black rice bran on amyloid β peptide production and abrupt increase in postprandial blood glucose levels in mice

Alzheimer's disease and type 2 diabetes are very serious diseases with the latter having been suggested to cause the former. We prepared super-hard rice bread blended with black rice bran (SRBBB), which contained a high amount of resistant starch that showed strong inhibitory activities against β-secretase and acetylcholinesterase even after heating. Black rice bran showed greater β-secretase inhibitory activity (3.6-fold) than Koshihikari rice. The bran contained more oleic acid and anthocyanin, meaning that it is potentially a biofunctional food with a high antioxidant capacity. Furthermore, aged mice, which were fed a SRBBB diet for four weeks, showed lower amyloid β 40 peptide in the blood than mice fed a commercial diet (p < 0.01). Additionally, their initial blood glucose levels (BGLs) after 12 weeks of being fed SRBBB were significantly lower than those in the control group. Taken together, our results indicate SRBBB shows promise for inhibiting not only amyloid β production, but also abrupt increases in postprandial BGLs.