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Limited evidenceHeart & metabolic

Eucommia

Eucommia ulmoides bark (du zhong) has one small clinical trial showing a modest blood pressure reduction, and essentially nothing else in humans. The bone, joint and testosterone claims that dominate its marketing are animal-only.

What the science says

  • Small blood pressure reduction in the one published clinical trial Limited evidence

    A randomized, placebo-controlled trial of a standardized Eucommia ulmoides bark extract in adults with mild-to-moderate hypertension found reductions of roughly 5-8 mmHg systolic and a few mmHg diastolic over 8 weeks at doses of 1,000-1,500 mg/day, with good tolerability. This is a single small trial with an industry-standardized extract and has not been replicated. The proposed mechanism involves geniposidic acid, chlorogenic acid and pinoresinol diglucoside acting on vascular tone.

  • Bone and joint claims are preclinical only Limited evidence

    Du zhong's classical use is for lower back and knee weakness, and rodent work shows Eucommia extract preserves bone mineral density in ovariectomized rats and reduces cartilage degradation in osteoarthritis models. No human trial has measured bone density, fracture risk, or joint pain outcomes with eucommia. Anyone taking it for osteoporosis is extrapolating from rats.

  • Testosterone and "kidney yang" claims have no human data Limited evidence

    Eucommia appears in testosterone-booster stacks based on its traditional tonic classification and a handful of rodent studies reporting increased serum testosterone. There is no placebo-controlled human trial measuring androgens, libido, or strength with eucommia at any dose.

Dosage & safety

Studied doseThe clinical trial used 1,000-1,500 mg/day of a standardized bark extract in divided doses for 8 weeks. Traditional decoctions use 6-15 g/day of dried bark, often salt-processed, within a formula. Western capsules supply 300-1,000 mg of bark extract, sometimes standardized to chlorogenic acid; note that eucommia leaf (used for tea in Japan and Korea) has a different constituent profile from the bark, and most clinical interest concerns the bark.
SafetyTolerability in the one clinical trial was good, with mild and infrequent side effects. Because it lowers blood pressure, additive hypotension is plausible with antihypertensive medication — monitor if combining, and be alert for dizziness. Some animal data suggest sedative effects; caution with CNS depressants. No safety data in pregnancy or breastfeeding — avoid, despite its traditional use for threatened miscarriage in Chinese medicine, which is not backed by any modern safety evaluation. Eucommia bark harvesting is destructive to the tree, and sustainability and species-substitution concerns exist in the supply chain. The overall human safety database is very small, so the absence of reported harms should not be read as an established safety record.

Scientific references

Where to buy

Swanson Vitamins, Full Spectrum® Eucommia Bark, 400 mg, 60 Veggie Capsules

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