At the 74th International Congress and Annual Meeting of the Society for Medicinal Plant and Natural Product Research (GA), which took place in Reims, France from Aug. 30 to Sept. 2, Stefan Gafner, chief science officer of the American Botanical Council (ABC), presented data detailing the scale of the problem.
According to data from three reviews conducted by ABC, gingko showed the highest rates of adulteration at 57%, followed by black cohosh (42%), echinacea (29%), ginseng (25%), elderberry (17%) and turmeric (22%).
For gingko, adulteration rates have risen significantly over the past two decades, increasing from around 39% from 2006 to 2010. Contributing factors include trade wars, military conflicts, climate change, diseases and spikes in demand, Gafner said.
“If you impose a tariff on another country and the raw materials get 50% more expensive, some companies will start to take shortcuts,” he noted. “There’s also military conflicts. Currently, with the war in Iran, gas prices are much higher which has increased shipping costs. Fertilizer costs have massively increased, too. As raw materials get more expensive, some companies start to cheat.”
Climate change and spikes in consumer demand can also reduce the availability of botanical ingredients and lead to increased adulteration rates, Gafner added, contributing to a fragmentation of the market in which reputable, tested brands compete against less expensive but lower quality products.
Methods of adulteration
ABC defines adulteration as accidental or intentional deviations in declarations of a botanical ingredient’s identity, strength, composition, geographic origin or production methods.
The methods of adulteration are wide-ranging and often vary in function of the desired outcome. Where cost reduction is the primary issue, manufacturers may dilute products by adding large quantities of fillers such as maltodextrin, thereby reducing the potency of the finished product.
Alternatively, some companies use chemical markers from other plants to reduce the cost of production while evading detection with simple chemical marker tests. This presents a risk to consumer health depending on which plant compounds are used.
Adulteration with pure compounds is also becoming more common, according to Gafner, citing data recently obtained by Morris Zelkha, CEO and co-founder of TriNutra, showing that Nigella sativa oils are often spiked with synthetic thioquinone.
Essential oils are also at risk of degradation as a result of improper handling, storage or processing.
“We had four samples where the free fatty acids were extremely high—four to five times higher than permissible limits,” Gafner said. “That basically means the oils are probably rancid. They may have been processed in an inappropriate manner or just stored badly, but this is not something that you would like to use.”
Essential oils are increasingly at risk of adulteration, with a review of studies finding that approximately 65% of tested bergamot oils, 52% of lavender oils and 42% of peppermint oils were adulterated.
Gafner highlighted 126 case reports of seizures associated with eucalyptus oil use identified in India between 2018 and 2023, following oral and topical use as well as inhalation. An analysis of several samples identified monoterpene ketones such as isofenchone, which are known to induce seizures.
“These monoterpene ketones are by-products of camphor synthesis,” he explained. “If you make camphor for the pharmaceutical industry, you start with turpentine oil to extract alpha-pinene and then you end up with camphor crystals, but the mother liquid around the camphor crystals contains exactly these compounds, so I assume that [companies] would just pipet it off, mix it and sell it as eucalyptus oil. This is really dangerous.”
Another significant concern for the supplement industry is the spiking of herbal products with pharmaceutical drugs to produce an immediate, noticeable effect. Certain sexual enhancement supplements, for example, have been found to contain sildenafil, the active ingredient in Viagra. When taken alongside nitrate medication, sildenafil can cause a dangerous drop in blood pressure.
Other companies have been found to use illegal botanical ingredients to produce therapeutic effect. Examples shared by Gafner included a Mexican Hawthorne supplement adulterated with yellow oleander that led to cardiovascular side effects requiring hospitalization and a kava supplement containing undeclared kratom and akuamma that reportedly led to opioid dependence.
“This is a very concerning type of adulteration,” he said.
What is being done to combat adulteration?
The ABC is actively combatting botanical adulteration through its Botanical Adulterants Prevention Program (BAPP).
Founded in 2011 with the American Herbal Pharmacopoeia (AHP), and the University of Mississippi’s National Center for Natural Products Research (NCNPR), BAPP has produced over 100 peer-reviewed documents exposing the extent of botanical adulteration. The aim is to equip suppliers, manufacturers and regulators with the scientific tools needed to detect poor-quality materials and source authentic ingredients.
A recent survey of industry members undertaken by the ABC showed that around 90% of respondents changed their quality control procedures as a result of the council’s publications, and around half said they changed suppliers.
Despite BAPP’s best efforts, however, botanical adulteration persists. As a result, some researchers have taken matters into their own hands. For example, Dr. Jenna Forsyth, an environmental health scientist at Stanford University, recently discovered that turmeric in Bangladesh was being adulterated with lead, causing high blood lead levels in rural populations.
Forsyth went to the authorities in Bangladesh and strategically placed posters around the country warning traders about the danger of lead adulteration. The authorities consequently provided inspectors with hand-held X-ray devices to check the quality of the turmeric being sold. Within three years, adulteration rates dropped from around 30% to 40% to zero.
“So, there are ways to deal with adulteration,” Gafner said. “It can be eliminated if there’s a will and if authorities, educators and academic institutions collaborate. This gives me hope also that our efforts at the Botanical Adulterants Prevention Program may lead to something tangible.”
