Most people don’t know what dangers could lurk in their cabinets—whether it’s their spice cabinet or their medicine cabinet. I’m not talking about pests, either. It is possible that some products billed as herbal medicines or even some spices, made under poor quality control practices, could be adulterated somewhere in the manufacturing process, either by accident or by a company’s attempt to increase profit margins by substituting materials. Either way, consuming an adulterated material could harm your health.
The sale of botanical supplements has increased dramatically. According to the American Botanical Council’s HerbalGram journal, in the U.S. alone, botanical supplement sales experienced record growth in 2018, increasing by an estimated 9.4% from 2017, the strongest growth since 1998. Meanwhile, concerns about economically motivated adulteration have grown as well. Adulteration of botanical ingredients with another botanical species is one of the most fundamental quality issues for botanical supplements, and in the United States, the law prohibits the sale of adulterated products. The presence of undeclared botanical species leads to adverse impacts on consumer confidence in the sector and potentially consumer health.
In the best-case scenario, the efficacy of the botanical product claim is not supported, and the only injury is to your wallet. Take for example, black cohosh (Actaea racemosa), a flowering plant native to eastern North America that is mainly used to alleviate premenstrual discomfort in women. Adulteration of black cohosh with Asian species is influenced by the low price of Asian Actaea materials1.
However, these Asian species are not substances that have been studied to establish a benefit for women’s health.
Similarly, in your spice cabinet you probably have a botanical product as common as dried parsley (Petroselinum crispum) leaf. Parsley is an herb widely consumed for its health benefits in gastrointestinal disorders, diabetes, hypertension, and cardiovascular diseases. However, celery leaf (Apium graveolens) has similar structural features and chemical profiles to parsley. The celery leaf is sometimes a source of substitution in commercial parsley materials because it is more economical. So, while it may not be a danger to your health, it is not what you paid for and you may not be receiving all the benefits of the botanical you thought you purchased.
In the worst-case scenario, serious safety consequences can arise from using alternate ingredients. For example, star anise (Illicium verum), a popular food spice and ingredient for some medicines, can be adulterated with Japanese star anise (Illicium anisatum) due to mistakes in harvesting, because of their similar appearance, or through deliberate economically motivated adulteration. Such adulteration could cause serious neurological effects or kidney and digestive organ damage2.
What’s the Fix?
Botanical adulteration can generally be prevented and overcome by rigorously identifying and testing raw botanical materials during the manufacture of botanical products—steps required by current good manufacturing practices (cGMPs). To implement the highest quality standard for botanical materials, a combination of test methods that address raw botanical material identification from different angles should be applied.
Morphological examination, including macroscopic and microscopic, is essential in detecting foreign matter and discriminating plant parts. However, it is difficult to use morphological examination to confirm all the available taxonomic features, especially for fine powder and plant parts that lack species-specific, unique features.
Phytochemical analyses, which usually target marker compounds or reference material phytochemical profiles, are the most widely used approach for botanical identification. These are powerful tools to confirm the presence of target botanical species, even plant parts, and detect adulteration based on prior knowledge. But they may still fall short when testing botanical species that are not well studied (e.g. limited data on marker compounds and adulterants) and bulk materials partially substituted with the motivation to maximize profit.
With progress being made in molecular biology, genomic tools like DNA testing not only provide a reliable means of understanding the relationship between plants but also show their potential in quality control of botanical materials, especially the identification of botanical raw materials.
It is important that such testing be conducted to rigorous standards and with understanding of the false positives that testing might produce, as well as environmental factors in test validity. Even the best test method can be applied incorrectly, or results interpreted poorly.
Companies should utilize all tools to fight botanical adulteration in the manufacture of botanical products. Dietary supplement ingredients are required, under U.S. cGMP regulations, to have their identity verified by at least one appropriate test or examination. For the benefit and safety of consumers, manufacturers of ingredients and manufacturers of supplements need to take the initiative to utilize all validated tools that are available to detect and halt the use of adulterated ingredients and make best efforts to minimize the risks related to the entrance of noncompliant products into the market. This means considering when multiple test might be required, and under what conditions, to ensure that results are reliable.
Although research projects on the application of genomic tools in highly processed and finished products is still ongoing, there are many affordable genomic-based test methods now considered fit-for-purpose3,4, to complement widely used morphological and chemical methods on the proper identification of raw botanical materials in routine quality control.
Zhengfei Lu is a senior analytical scientist at Herbalife Nutrition.
1. Foster S. “Exploring the peripatetic maze of black cohosh adulteration: A review of the nomenclature, distribution, chemistry, market status, analytical methods and safety.” HerbalGram, Issue 98 (2013): 32-51
2. Perret C. et al. “Apparent life-threatening event in infants: think about star anise intoxication.” Archives de Pediatrie, vol. 18, no. 7 (July 2011): 750-753
3. Dhivya S. et al. “Validated identity test method for Ginkgo biloba NHPs using DNA-based species-specific hydrolysis PCR probe.” Journal of AOAC International, vol. 102, no. 6 (November 2019): 1779-1786
4. Lu Z. et al. “Single-laboratory validation of a two-tiered DNA barcoding method for raw botanical identification.” Journal of AOAC International, vol. 102, no. 5 (September 1, 2019) 1435-1447