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Efficacy and Safety of Sakurajima Radish in Patients with Metabolic Syndrome: A Phase IIb Randomized, Three-Period Crossover Trial

Tokushige A, Akasaki Y, Shibata K, Sakoda T, Tajima A, Kajiya T, Shirasawa N, Hamada N et al.

Nutrients, 2026

21 participants

Abstract

Background/objectives: We aimed to evaluate the efficacy and safety of a short-term dietary intervention using trigonelline-rich Sakurajima radish on vascular endothelial function in patients with metabolic syndrome (MetS).

Methods: In this multicenter, open-label, randomized, three-period crossover phase IIb trial, 21 patients with MetS were assigned to three 14-day sequences (Sakurajima radish powder, Aokubi radish powder, and a usual diet), separated by 14-day washouts. The primary outcome was flow-mediated dilation (FMD). Key Secondary outcomes included blood pressure (BP), urinary nitric oxide metabolites (NOx), and the oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG).

Results: Sakurajima radish did not improve FMD versus the usual diet (p = 0.58) or Aokubi radish (p = 0.59), although a significant negative carryover effect following the Aokubi period likely confounded this estimation. Despite successfully stimulating NO production (elevated urinary NOx, p = 0.03), the intervention paradoxically increased oxidative stress (elevated 8-OHdG/creatinine, p = 0.02) and significantly elevated systolic BP compared with the usual diet (+9.67 mmHg, p = 0.03) and Aokubi radish (+8.86 mmHg, p = 0.04).

Conclusions: Sakurajima radish does not appear to improve endothelial function in patients with MetS within the constraints of this short-term crossover design. Importantly, the unexpected negative carryover effect inherently limits the interpretability of this primary…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 21 participants or records.

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