The ABC-AHP-NCNPR Botanical Adulterants Prevention Program (BAPP) recently published a review on turmeric adulteration in the peer-reviewed journal Pharmaceutical Biology. The special issue focuses on the safety, efficacy, and quality of turmeric, and marks BAPP’s 100th peer-reviewed publication since it was founded in 2011.

Turmeric (Curcuma longa) is widely used as a spice and as an ingredient in dietary supplements and other herbal products, and was the top-selling herb in the U.S. natural expanded channel and fourth top-selling herb in the U.S. mainstream channel in the American Botanical Council’s 2024 Herb Market Report. Reports on commercial products have found instances of adulteration with artificial dyes, undeclared diluents like cornstarch, and synthetic curcumin, among other lower-cost substances.

Turmeric has historically been adulterated, with records dating back to the 19th century. Synthetic dye adulterants, such as metanil yellow, which is classified as potentially genotoxic and carcinogenic, appear to have been used in the turmeric trade since the 1960s, while records dating back to around 1980 detail adulteration with undeclared bulking agents, pre-extracted turmeric root powder, and other Curcuma species. Synthetic curcumin is a more recent phenomenon, with the earliest reports dating to the early 2010s.

The review also covers information about the supply chain, a history of turmeric adulteration, geographical differences in adulteration practices, and the methods used to detect adulteration.

The new BAPP publication included 48 scientific papers covering lab assessments of proper identity and authenticity of commercial products as whole or powdered rhizomes/roots, and both non-standardized and curcumin-standardized extracts. 448 of the 2,235 turmeric products tested across these studies were considered to be adulterated, placing the adulteration rate at around 20% (22% for supplements and 20.4% for turmeric sold as a spice).

The review was authored by Stefan Gafner, PhD, chief science officer of ABC; Nilüfer Orhan, PhD, a research scientist at ABC and BAPP; Çiğdem Kahraman, PhD, assistant professor of pharmacognosy at Hacettepe University in Ankara, Türkiye; and Mark Blumenthal, founder and executive director of ABC.

“What I find encouraging in the case of turmeric, is that a combination of education, inspections, and regulatory measures has led to a substantial reduction in the amount of adulterated turmeric in certain areas of the world. This means that the problem of adulteration can be solved, and that education, which is the main focus of the Botanical Adulterants Prevention Program, is an essential part of the solution,” said Gafner.

“BAPP’s new turmeric paper is a significant milestone for the responsible sector of the herb and medicinal plant community,” said Blumenthal. “Since turmeric is consistently documented as one of the top-selling herbal dietary supplements in the United States, it is fitting that it should be the subject of BAPP’s 100th peer-reviewed publication. And, it should be noted that there are many authentic and reliable turmeric products that are produced and sold by responsible companies.”

“All of us here at the American Botanical Council, the American Herbal Pharmacopoeia, and the National Center for Natural Products Research at the University of Mississippi, the three BAPP partner organizations, are grateful to the many responsible companies and organizations in the United States and internationally that have supported BAPP since its founding 15 years ago,” Blumenthal continued. BAPP’s longevity and productivity represent the very best efforts of responsible elements of the herb industry and related research and natural medicine communities to take initiative and leadership in helping to ensure the authenticity of natural plant- and fungal-based ingredients and to reduce the scourge of adulteration and fraud in the global marketplace.”