Research

Hormonal

Onion peel extract supplementation significantly improves endothelial function (Flow-Mediated Dilation) and increases circulating endothelial progenitor cells in overweight and obese patients, although it may not significantly reduce blood pressure or body weight in the general hypertensive population.

For individuals with obesity and hypertension, consuming onion peel extracts (rich in quercetin) may support vascular health by improving blood vessel function and increasing protective endothelial cells. This benefit exists even if overall blood pressure or body weight changes are modest in the general population.

ModerateQualifiesMEDIUM confidence
In the onion treated group a significantly improvement in FMD values between baseline and 12-weeks follow-up was observed... The percentages of EPCs were significantly increased in the onion consumption group as well... Overall, quercetin-rich onion did not affect 24 h ABP parameters and office BP in the total group. On the contrary, blood pressure was significantly affected in the subgroup of hypertensive patients.
Mariangela Marrelli et al. · Molecules · 2018

Why this rating

Based on small, short-term human clinical trials (12 weeks) with mixed results on primary endpoints (BP/Weight) but positive secondary endpoints (FMD/EPCs).

Source

Biological Properties and Bioactive Components of Allium cepa L.: Focus on Potential Benefits in the Treatment of Obesity and Related Comorbidities

Mariangela Marrelli et al. · Molecules · 2018

DOI 10.3390/molecules24010119

narrative_reviewCited 185×
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DOI resolved against Crossref · corpus check 2026-06-10

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