Supplement analysis backed by scientific evidence · PT

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Limited evidenceImmunity

Goldenseal

Goldenseal has no credible clinical evidence for any of the infections it is sold for, and it is one of the strongest herbal CYP3A4 inhibitors ever measured in humans — meaning its best-documented biological effect is a drug interaction, not a benefit. It is also a threatened wild-harvested plant.

What the science says

  • Colds, sinus and respiratory infections Limited evidence

    Despite being a top-selling "immune" herb, goldenseal has no randomized controlled trials showing it prevents or treats any respiratory infection. Its reputation is borrowed from berberine's in-vitro antimicrobial activity, but goldenseal root contains only about 2-6% berberine and oral berberine has very low bioavailability (under 1%), so systemic antimicrobial concentrations are not plausible.

  • Clinically significant CYP3A4 inhibition Strong evidence

    In a controlled human phenotyping study, 3,210 mg/day of goldenseal for 14 days inhibited CYP3A activity by roughly 40%, an effect comparable to some prescription inhibitors, and an earlier trial in the same programme found simultaneous inhibition of CYP2D6. This is the best-replicated effect of goldenseal and it is a hazard, not a benefit — it can raise blood levels of statins, calcium-channel blockers, immunosuppressants, benzodiazepines and many other drugs.

  • Masking drug tests Limited evidence

    The folk belief that goldenseal masks urine drug screens dates to a 19th-century novel and has been repeatedly disproven; it does not interfere with modern immunoassay or GC-MS testing.

Dosage & safety

Studied doseNo evidence-based dose exists. Products typically supply 500-1,000 mg of dried root two to three times daily, or extracts standardized to 5-10% alkaloids. The human interaction study used 3,210 mg/day of powdered root. Given the interaction data, dosing recommendations are not clinically appropriate for most people.
SafetyThe dominant concern is drug interactions: strong CYP3A4 and CYP2D6 inhibition, plus P-glycoprotein effects, can produce dangerous increases in concurrent drug levels — do not combine with statins, ciclosporin, tacrolimus, midazolam, many antiarrhythmics or antidepressants without medical supervision. Berberine-containing plants displace bilirubin from albumin and can cause kernicterus in neonates: goldenseal is contraindicated in pregnancy, in breastfeeding and in newborns. High doses can cause GI upset, mouth ulceration and, rarely, hypertension or seizures. Hydrastis canadensis is listed on CITES Appendix II as a threatened wild-harvested species — much commercial "goldenseal" is also adulterated, so certified cultivated sourcing matters.

Scientific references

Where to buy

Nature's Way, Goldenseal Root, 100 Vegan Capsules (333 mg per Capsule)

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