ConsumerLab finds lead in two goldenseal supplements and little berberine in a third

Five of six berberine supplements passed ConsumerLab's quality testing, but all three goldenseal supplements in the same round failed — one contained almost none of the expected berberine, and two were contaminated with lead, according to the testing group's review of products tested in 2023 ^[2].

What the tests found

ConsumerLab, an independent testing service that sells subscriptions to its reviews, said it tested 10 different products ^[1]. The review reports results for 10 supplements: nine selected by ConsumerLab and one additional product that passed the same testing through the company's voluntary Quality Certification Program ^[2].

Berberine is a yellow-colored compound found in goldenseal root. As a supplement it is typically sold as berberine HCl, which is 90% berberine, in capsules or tablets containing hundreds of milligrams. Goldenseal root powder or extract supplements generally provide less than 30 mg of berberine per serving, ConsumerLab said ^[2].

The review's product list includes items from Amazing Formulas, Bone Science, GlucoVantage, GNC, Eclectic Herb, Enzymedica, Natural Factors, Nature's Way, Nutricost, Solaray and Swanson ^[2]. The summary says three goldenseal supplements were selected for testing, while the alphabetical product list shows four products named for goldenseal ^[2]. Which specific products passed or failed, and how much lead was found in the two contaminated goldenseal products, is not disclosed in the public summary; full results and ConsumerLab's "Top Picks" require a paid membership ^[1][2].

Quality problems in berberine products are not new. ConsumerLab summarized a 2017 study of 15 products sold in the U.S. in which nine contained only 33% to 89% of their claimed amounts of berberine ^[1].

Why it matters for patients

Berberine has been marketed as "Nature's Ozempic," a reference to semaglutide, the active ingredient in Ozempic and Wegovy. ConsumerLab said the effects of semaglutide are much greater and better supported by evidence than those of berberine, and that berberine has not been shown to cause weight loss ^[2]. The company also said there is insufficient evidence that goldenseal root powder or extract treats or prevents any condition ^[2].

For people taking a GLP-1 drug or deciding whether to add a supplement, the results point to a practical gap: what is on the label is not always what is in the bottle. ConsumerLab said berberine can increase bilirubin levels and should not be taken by women who are pregnant or nursing or by young children; it may also affect blood sugar and blood pressure and can interfere with the activity of many drugs ^[2]. The products that failed testing are not named outside the paid review ^[1][2].

What happens next

ConsumerLab said it continues to update the review as products are added, including through its certification program; Bone Science Prime Berberine was recently approved for quality and added to the review ^[1][2]. No date for a next round of testing has been reported ^[2].