A Comparison of British and <scp>US</scp> Pharmacopoeia Standards for Quality of Ashwagandha Dietary Supplements in Commerce

Pharmacopeias are essential for ensuring the quality of botanical raw materials, yet their utility is limited by slow adaptation to rapid innovation in the dietary supplement industry. Challenges arise from differing standards (e.g., the British Pharmacopoeia (BP) and the United States Pharmacopoeia (USP)), as well as a critical lack of comparative data for globally sourced ingredients. The post-COVID surge in adaptogens, such as ashwagandha, underscores the urgency of these issues. The commercial use of aerial parts-despite traditional root-only use and phytochemical variability-raises concerns about quality and safety. The situation necessitates rigorous source verification and re-evaluation of current pharmacopeial methods. To address these deficiencies, we developed and compared an HPLC-PDA method utilizing BP and USP standards to quantify three steroidal lactones (withaferin A, withanolide A, and withanoside IV) in ashwagandha samples and commercial products. Our analysis revealed substantial variations in steroidal lactone content. Alarmingly, over 44% of products failed to meet BP standards, and 60% failed to meet USP standards. The high failure rate was attributed to the elevated presence of co-eluted dihydrowithaferin sulfate, primarily found in leaf samples, which led to an underestimation of withanolide A. Only 10 of 25 supplement products met both standards; only two were confirmed as root-derived, while the remainder contained varying proportions of (un)disclosed aerial parts. These findings highlight critical plant-part-specific chemical variations and the need for enhanced source verification and improved quality control. Developing robust analytical methods and revisiting existing pharmacopeial guidelines are crucial for assessing the quality and safety of ashwagandha products, including novel formulations.