Sakurajima radish and blood vessel function in metabolic syndrome
What it found
In 21 people with metabolic syndrome, 14 days of Sakurajima radish powder did not improve blood vessel function.
It did raise a marker of oxidative stress and systolic blood pressure.
What they found
Studies in people
Blood vessel function
Sakurajima radish did not improve flow-mediated dilation compared with the usual diet or Aokubi radish. The authors note that a carryover effect from Aokubi radish may have interfered with this measurement.
Systolic blood pressure
Systolic blood pressure was higher after Sakurajima radish than after the usual diet (by 9.67 mmHg) and after Aokubi radish (by 8.86 mmHg). Diastolic blood pressure changes were not statistically significant.
Oxidative stress marker
Urinary 8-OHdG, a marker of oxidative DNA damage, was higher after Sakurajima radish than after the usual diet. The difference from Aokubi radish was not significant.
Nitric oxide metabolites
Urinary nitric oxide metabolites were higher after Sakurajima radish than after the usual diet, suggesting the intervention stimulated nitric oxide production. The comparison with Aokubi radish was not significant.
Lipids and inflammatory markers
Total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, high-sensitivity troponin I, and pentraxin 3 showed no statistically significant differences between Sakurajima radish and the other periods.
Taste and side effects
Sakurajima radish scored higher for sweetness and umami than Aokubi radish, and palatability was similar. Adverse events were generally mild, mostly transient stomach or gut symptoms that resolved without stopping the intervention.
What the authors conclude
“Sakurajima radish does not appear to improve endothelial function in patients with MetS within the constraints of this short-term crossover design.”
Also in their conclusions
- They conclude that Sakurajima radish does not appear to improve endothelial function in patients with metabolic syndrome within the constraints of this short-term crossover design.
- They say the unexpected negative carryover effect limits the interpretability of the primary FMD outcome, as it may have masked potential benefits.
- They advise that NO-boosting functional foods may cause unintended adverse hemodynamic responses in people with metabolic syndrome, and call for careful risk-benefit evaluation and parallel-group trial designs.
How it was done
The authors wanted to see whether a radish rich in trigonelline, which boosted blood vessel function in healthy people, would also help people with metabolic syndrome. They also asked whether the high oxidative stress in metabolic syndrome might change how the body handles the extra nitric oxide.
They ran a randomised crossover trial in 21 patients with metabolic syndrome. Each person took Sakurajima radish powder, Aokubi radish powder, or stayed on their usual diet for 14 days each, with 14-day washouts in between. The main measure was flow-mediated dilation of the brachial artery.
What it can’t tell you
- This was a 14-day study in 21 people with metabolic syndrome, so it cannot show what would happen over longer periods or in other groups.
- The carryover effect from Aokubi radish may have distorted the blood vessel function results, so the true effect of Sakurajima radish on FMD is unclear.
- The study measured surrogate markers, not long-term cardiovascular outcomes, so it cannot show whether these changes affect heart disease risk.
Who paid
- Conflicts
- The authors declare no conflicts of interest. In addition, the funders had no involvement in the study design, data collection/analysis, or manuscript writing.
- Authors work at
- Kagoshima University, Japan; University of the Ryukyus, Japan; Tenyoukai Central Hospital, Japan
The paper
- Title
- Efficacy and Safety of Sakurajima Radish in Patients with Metabolic Syndrome: A Phase IIb Randomized, Three-Period Crossover Trial
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Tokushige A, Akasaki Y, Shibata K, et al (2026). Efficacy and Safety of Sakurajima Radish in Patients with Metabolic Syndrome: A Phase IIb Randomized, Three-Period Crossover Trial. Nutrients. doi:10.3390/nu18111801Free full textPubMed 42280444DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error