Effects of Sakurajima-radish (<i>Raphanus sativus</i> cv. Sakurajima Daikon) and trigonelline on nitric oxide (NO) production from vascular endothelial cells and human vascular endothelial function

In Japan, there is an approximate 10 year gap between average life expectancy and healthy life expectancy, which represents a decade characterized by poor health. To shorten this period and promote healthy aging, we searched for food ingredients that promote vascular health. Focusing on nitric oxide (NO) released by vascular endothelial cells, we first established an evaluation method to measure the NO production capacity of the vascular endothelium in real-time. This helped identify Sakurajima-radish (Raphanus sativus cv. Sakurajima Daikon), which promotes NO production in vascular endothelial cells. The ability of Sakurajima-radish to induce NO production was observed in both the edible part of the enlarged root and the leaves to an equal extent. We identified the active component, trigonelline, and found that Sakurajima-radish contains much higher amounts of trigonelline than other natural products. There was no statistically significant difference in trigonelline content among the varieties of Sakurajima-radish distributed across Kagoshima Prefecture, nor was there any significant difference among the production areas within Kagoshima Prefecture, including outlying islands. The trigonelline content of Sakurajima-radish remained relatively stable across most cooking methods. A clinical study involving healthy individuals showed that Sakurajima-radish consumption (170 g/day for 10 days) caused a significant increase in flow-mediated dilation and blood trigonelline levels. This article elucidates the potential of Sakurajima-radish as a functional food that can be stored, cooked, and eaten in various forms with significant health benefits contributing to improved vascular function.