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BAPP Publishes Botanical Adulterants Prevention Bulletin on Maca Root and Laboratory Guidance Document on Tea Tree Oil


The ABC-AHP-NCNPR Botanical Adulterants Prevention Program (BAPP) has released two new publications: a Botanical Adulterants Prevention Bulletin on maca (Lepidium meyenii syn. L. peruvianum, Brassicaceae) root* and root extract and a Laboratory Guidance Document (LGD) on tea tree oil, the essential oil obtained from the leaves of tea tree (Melaleuca alternifolia and M. linariifolia, Myrtaceae).

Maca Bulletin Describes Undeclared Addition of Flours from Corn, Wheat, or Yam

Maca roots have been cultivated in the Peruvian Andes for thousands of years as a nutritious food, and have a history of use as a medicine to enhance fertility, to provide energy, and for their effects on mood and well-being.

The use of maca as a dietary supplement is relatively recent. It was a little-known ingredient in the United States market before 2000, but retail sales have started to increase over the last decade. US retail sales exceeded a total of $15 million in the natural and mainstream retail channels in 2017, according to HerbalGram’s 2017 Herb Market Report. Maca ranked eighth in the natural channel and 36th in the mainstream channel.



Though maca is native to the Andes, its popularity in the past few years, especially in Asian countries as a means to enhance sexual stamina, has led to large amounts being grown in China from roots smuggled out of Peru. This has caused uncertainty about supply volume and pricing. At the same time, published reports have highlighted the undeclared dilution of maca root powders with flours from corn (Zea mays, Poaceae), wheat (Triticum aestivum, Poaceae), or yam (Dioscorea spp., Dioscoreaceae). As with other herbal ingredients marketed to boost sexual stamina, there is also evidence of the illegal sale of conventional sexual enhancement drugs (e.g., sildenafil) masquerading as maca dietary supplements.

The maca bulletin was authored by Jeremy Stewart, PhD, vice president of scientific affairs at herbal products manufacturer Gaia Herbs (Brevard, North Carolina), and Bill Chioffi, former vice president of global sourcing and sustainability at Gaia Herbs. It summarizes the published data on maca adulteration, details supply chain issues and their consequences for the maca market, and discusses maca’s market importance. It also includes a short section on analytical methods to detect adulteration. Fifteen quality control experts from academia and the herb industry in the United States and Europe provided input on the bulletin during the peer-review process.

“Maca is an example of a formerly obscure herb that has enjoyed recent popularity, and with this increased demand, unscrupulous suppliers have tried to take advantage of consumers by offering maca material adulterated with undisclosed lower-cost ingredients,” said Mark Blumenthal, founder and executive director of ABC and the director of BAPP. “We are deeply grateful to our friends at Gaia Herbs for their compilation of published data and technical information for the maca bulletin.”

Stefan Gafner, PhD, chief science officer of ABC and technical director of BAPP, commented: “The adulteration of maca root, or any botanical ingredient, with undisclosed lower-cost material is unacceptable. It is our hope that these issues will altogether disappear once the supply chain has stabilized. Nevertheless, maca dietary supplement manufacturers should be aware of the potential authenticity issues that can occur.”

The goal of the Botanical Adulterants Prevention Bulletins is to provide accounts of ongoing issues related to botanical identity and adulteration, thus allowing quality control personnel and lab technicians in the herbal medicine, botanical ingredient, dietary supplement, cosmetic, herbal tea, conventional food, and other industries where botanical ingredients are used to be informed about adulteration problems that are apparently widespread and/or imply safety concerns.

LGD Assesses Strengths and Limitations of Lab Methods to Verify Authenticity of Tea Tree Oil

Tea tree oil is a popular ingredient known for its antimicrobial properties. Medicinally, it is widely used as a topical treatment for minor cuts, wounds, and other skin problems, and as an inhalant or in chest rub formulations to help alleviate symptoms of the common cold. In addition, it frequently is included as an ingredient in animal care, home care, personal care, and cosmetic products. Australia is the major producer of tea tree oil, providing an estimated 80% of the global supply. In 2018, Australian tea tree oil exports reached a market value of AU$35 million (roughly US$21 million).1

Due to the relatively high cost of authentic tea tree oil, some suppliers substitute materials labeled to contain tea tree oil with lower-cost adulterants. Tea tree oil adulterants include monoterpene-rich materials obtained from the industrial waste stream after the purification of camphor (Cinnamomum camphora, Lauraceae), eucalyptus (Eucalyptus globulus and other Eucalyptus spp., Myrtaceae), and pine (Pinus spp., Pinaceae) essential oils. Tea tree oil also can be adulterated by adding pure chemical compounds that originate from fermentation, chemical synthesis, or other plant materials.

Common analytical assays to evaluate the identity of essential oils include organoleptic (sensory) evaluations, physicochemical tests, and chemical methods. The main advantages and disadvantages of each analytical method and their usefulness to detect tea tree oil adulteration have been summarized by Gafner and Ashley Dowell, manager of the Analytical Research Laboratory at Southern Cross University (East Lismore, New South Wales, Australia).

In addition to the assessment of analytical methods, the document details the chemical composition of tea tree oil, potential confounding species, and known adulterants. The LGD was peer-reviewed by 13 international experts from third-party contract analytical laboratories and the herbal industry.

“In the past three decades, tea tree oil has become a significant ingredient in many consumer health products, particularly topical products used for their antibacterial, antifungal, or other beneficial health effects,” said Blumenthal. “The rise in tea tree’s popularity has motivated unscrupulous suppliers to add cheap, sometimes synthetic chemicals to materials that are fraudulently marketed as ‘tea tree oil’ in international commerce. The tea tree oil LGD will help enhance the quality control process and help protect companies and consumers from being victimized by sellers of fraudulent material.”

Gafner commented: “Essential oils have a long history of being adulterated. As unethical suppliers become more sophisticated in their ways of substituting essential oils with lower-cost materials, companies that manufacture products with ingredients such as tea tree oil need the right tools to detect potential adulteration. I hope that the tea tree oil LGD will be a useful contribution in helping companies select the best methods for the task at hand.”

BAPP’s LGDs identify the most suitable analytical methods for detection of certain adulterants and authentication of specific botanical materials in various forms (whole, cut, powdered raw materials, extracts, juices, and/or essential oils). Positive assessments of analytical methods are based on a thorough review of available methods from official compendia and the peer-reviewed scientific literature, and sometimes those provided by botanical ingredient suppliers, manufacturing companies, and independent third-party analytical laboratories. The guidance is intended for quality control personnel in the herbal medicine, botanical ingredient, dietary supplement, conventional food, and cosmetic industry sectors.

About the ABC-AHP-NCNPR Botanical Adulterants Prevention Program

The ABC-American Herbal Pharmacopoeia (AHP)-National Center for Natural Products Research (NCNPR) Botanical Adulterants Prevention Program is an international consortium of nonprofit professional organizations, analytical laboratories, research centers, industry trade associations, industry members, and other parties with interest in herbs and medicinal plants. The program advises industry, researchers, health professionals, government agencies, the media, and the public about the various challenges related to adulterated botanical ingredients sold in commerce. More than 200 US and international parties have financially supported or endorsed the program.

To date, the program has published 45 peer-reviewed articles, Botanical Adulterants Prevention Bulletins, LGDs, and Botanical Adulterants Monitor e-newsletters. All of the program’s publications are freely available on the program’s website.

—ABC Staff


* Technically, in the case of maca, the plant part used is a tuber consisting of the root and the hypocotyl, the stem of a germinating seed just above the root.


  1. Brown J. Tea tree industry fights to keep its oil classified as a therapeutic good, not an aromatherapy product. The Land. Published April 19, 2018. Available at: Accessed September 15, 2018.