The humble red onion is earning a new reputation beyond the kitchen: its papery skins, often tossed in the trash, may actually help lower blood pressure naturally. This surprising possibility is backed by a growing body of scientific research focused on quercetin—a flavonoid richly concentrated in onion skins.
Multiple clinical trials have found that supplementation with quercetin extracted from red onion skins can significantly reduce blood pressure in people with hypertension. In one double-blind, placebo-controlled study, daily supplementation of 162 mg quercetin from onion skin extract lowered both systolic and diastolic blood pressure among hypertensive patients, suggesting a clear cardioprotective effect (PMC).
Quercetin’s effectiveness isn’t just theoretical. A meta-analysis and several independent studies have shown that this plant pigment is associated with significant reductions in both systolic and diastolic blood pressure, especially in people at risk for cardiovascular disease (DocWire News). The mechanism? Quercetin appears to improve endothelial function, reduce inflammation, and enhance blood vessel flexibility—all important factors in controlling blood pressure (Almanac).
It’s worth noting that the benefits appear most pronounced in people with diagnosed hypertension, rather than those with normal blood pressure. The effect size, while not as dramatic as some pharmaceutical drugs, is meaningful enough that researchers are calling quercetin-rich onion skin extract a promising adjunct for natural blood pressure management (NutraIngredients).
But before you rush to brew onion skin tea or buy supplements, remember that more isn’t always better. The effective dosage in studies has been around 162 mg of quercetin daily, and safety for long-term supplementation hasn’t been fully established for everyone. It’s always a good idea to consult your doctor before adding any supplement to your routine, especially if you’re already taking blood pressure medications (Healthline).
Still, the evidence is strong enough that scientists are taking notice, and onion skins—once overlooked kitchen scraps—are rapidly gaining popularity in the world of natural remedies for high blood pressure.