The DNA-Based Authentication of Commercial Herbal Products Reveals Their Globally Widespread Adulteration

The herbal products, sold worldwide as medicines or foods, are perceived as low risk because they are considered natural and thus safe. The quality of these products is ineffectively regulated and controlled. The growing evidence for their lack of authenticity is causing deep concern, but the scale of this phenomenon at the global, continental or national scale remains unknown. We analyzed data reporting the authenticity, as detected with DNA-based methods, of 5,957 commercial herbal products sold in 37 countries, distributed in all six inhabited continents. Our global survey shows that a substantial proportion (27%) of the herbal products commercialized in the global marketplace is adulterated when their content was tested against their labeled, claimed ingredient species. The adulterated herbal products are distributed across all continents and regions. The proportion of adulterated products varies significantly among continents, being highest in Australia (79%), South America (67%), lower in Europe (47%), North America (33%), Africa (27%) and the lowest in Asia (23%). The commercial HPs' authenticity among the 37 countries included in our global analysis ranges between 0 and 100% from the total number of product reported for each specific national marketplace. For 9 countries, more than 100 products were successfully DNA-based authenticated and reported. From these countries, the highest percentage of adulterated commercial HPs was reported for Brazil (68%), followed distantly by Taiwan (32%), India (31%), USA (29%), followed closely by Malaysia (24%), Japan (23%), South Korea (23%), Thailand (20%), and China (19%). Our results confirm the large-scale presence of adulterated herbal products throughout the global market. The adulterated herbal products contain undeclared contaminant, substitute, and filler species, or none of the labeled species, which all may be accidental or intentional, economically-motivated and fraudulent. Due to the ever-increasing analytical sensitivity of the high throughput DNA sequencing, increasingly used for the untargeted, simultaneous multi-taxa identification, the proportion of adulterated HPs detected on the global market is expected to increase. In the context of the increasing demand for HPs, the limited supply of raw materials derived from many plant species, some of which being already nationally or internationally protected and having various degrees of trade restrictions, adds up to the differences and discrepancies between national HPs' regulatory frameworks and further increases the risks of adulteration of many types of herbal products. The globally widespread adulteration is a serious threat to consumers' well-being and safety, in spite of herbal products' claimed or expected health benefits.