The quality and safety of <i>Rhodiola rosea</i> supplements on the U.S. market: An analysis of biomarkers, heavy metals, and pesticide residues

by Steffen Porwollik, Mahtab Jafari

Rhodiola rosea supplements have become popular in the U.S., with a $3.4 billion market and an annual growth of about 10% in sales in the past few years. While the health benefits of this plant have been evaluated in many scientific studies, the potential differences in quality of these botanical products on the U.S. market have not been studied in detail. Using reversed-phase ultra-performance liquid chromatography, we determined the concentrations of the biomarker molecules, rosavins and salidroside, in a small but representative sample of R. rosea dietary supplement products commercially available in the U.S. Concentrations of rosavins and salidroside ranged from 0.01% to 3.08% and 0.07% to 2.91%, respectively, including substantial aberrations from advertised biomarker amounts. One product showed an undisclosed likely addition of synthetic salidroside. We also assessed heavy metal contaminations via inductively coupled plasma mass spectrometry and pesticide contents by gas chromatography-mass spectrometry or liquid chromatography-mass spectrometry in these botanical products. While pesticide levels were below detection limits, all seven tested capsular products had trace amounts of arsenic, cobalt, and lead. Two of these contained notably elevated levels of cobalt and arsenic, where follow-up arsenic speciation would be required to verify whether they remain within minimal risk levels established by the U.S. Department of Health and Human Services. Overall, these results underscore the need for more stringent quality control in herbal supplements containing R. rosea available in the U.S.