DNA barcoding detects contamination and substitution in North American herbal products

TLDR: Most of the herbal products tested were of poor quality, including considerable product substitution, contamination and use of fillers, which suggests that the herbal industry should embrace DNA barcoding for authenticating herbal products through testing of raw materials used in manufacturing products.

Abstract: Background: Herbal products available to consumers in the marketplace may be contaminated or substituted with alternative plant species and fillers that are not listed on the labels According to the World Health Organization, the adulteration of herbal products is a threat to consumer safety Our research aimed to investigate herbal product integrity and authenticity with the goal of protecting consumers from health risks associated with product substitution and contamination Methods: We used DNA barcoding to conduct a blind test of the authenticity for (i) 44 herbal products representing 12 companies and 30 different species of herbs, and (ii) 50 leaf samples collected from 42 herbal species Our laboratory also assembled the first standard reference material (SRM) herbal barcode library from 100 herbal species of known provenance that were used to identify the unknown herbal products and leaf samples Results: We recovered DNA barcodes from most herbal products (91%) and all leaf samples (100%), with 95% species resolution using a tiered approach (rbcL + ITS2) Most (59%) of the products tested contained DNA barcodes from plant species not listed on the labels Although we were able to authenticate almost half (48%) of the products, one-third of these also contained contaminants and or fillers not listed on the label Product substitution occurred in 30/44 of the products tested and only 2/12 companies had products without any substitution, contamination or fillers Some of the contaminants we found pose serious health risks to consumers Conclusions: Most of the herbal products tested were of poor quality, including considerable product substitution, contamination and use of fillers These activities dilute the effectiveness of otherwise useful remedies, lowering the perceived value of all related products because of a lack of consumer confidence in them We suggest that the herbal industry should embrace DNA barcoding for authenticating herbal products through testing of raw materials used in manufacturing products The use of an SRM DNA herbal barcode library for testing bulk materials could provide a method for ‘best practices’ in the manufacturing of herbal products This would provide consumers with safe, high quality herbal products Background Globalization of trade is expanding natural product commodity markets that sustain life and promote good health, yet the challenging financial climate is squeezing profit margins and exacerbating the propensity for contamination, fraudulent market substitution and the use of unlabeled fillers This comes at a time when consumers are becoming increasingly concerned about the authenticity of the products they purchase North America is a major provider of goods such as herbal products, a commodity that has come under scrutiny recently in the media due to product substitution [1-3] The International Trade in herbal products is a major force in the global economy and the demand is increasing in both developing and developed nations There are currently more than 1,000 companies producing medicinal plant products with annual revenues in excess of US$60 billion Notably, medicinal herbs now constitute the most rapidly growing segment of the North American alternative medicine market [4,5], with over 29,000 herbal substances [6,7] generating billions of dollars in trade These statistics are indicative of the rapid growth