Oregano Herb and Oil Adulteration Data Summarized in New Botanical Adulterants Prevention Bulletin

Publication raises issue of economically motivated substitution of oregano herb with undeclared leaf and herb material from other plants

AUSTIN, Texas (October 28, 2019) — The ABC-AHP-NCNPR Botanical Adulterants Prevention Program (BAPP) announces the publication of a new Botanical Adulterants Prevention Bulletin (BAPB) on oregano herb and oregano essential oil.

Oregano (Origanum vulgare subsp. hirtum; O. onites) is one of the most popular herbs for culinary use especially in countries of the Arabian Peninsula, Europe, North Africa, and North America. Powdered oregano herb, herb extracts, and oregano essential oil are also popular as dietary supplement ingredients, which in the United States are primarily sold in natural retail stores, where oregano dietary supplements were the 10th top-selling dietary supplement with annual retail sales totaling roughly $10 million in 2017, according to the 2018 Herb Market Report published in the American Botanical Council’s (ABC’s) peer-reviewed journal HerbalGram. Besides its use in dietary supplements, oregano essential oil is included as an ingredient in formulations of the perfume and cosmetic industry.

A large number of plant species have the term “oregano” as part of their common name and therefore can be mistakenly sold instead of oregano. Some of these species are legally allowed to be used interchangeably, depending on their sale as a spice, dietary supplement, or cosmetic ingredient, while others are considered to be adulterants. Also problematic is the substitution of oregano herb with undeclared lower-cost plant materials to add volume (bulking agents), including the following plants: Cistus spp. leaf, hazelnut (Corylus avellana) leaf, strawberry (Fragaria spp.) leaf, myrtle (Myrtus communis) leaf, olive (Olea europaea) leaf, sweet marjoram (Origanum majorana) herb, sumac (Rhus spp.) leaf, summer savory (Satureja hortensis) herb, winter savory (Satureja montana) herb, and thyme (Thymus spp.) herb. Such inappropriate substitution and mislabeling appears to be fairly common according to a number of articles published over the last decade, many of which are referenced in the new bulletin.

Oregano oil is made from the distillation of the naturally occurring essential oil in oregano leaves and other aerial parts of the plant. Information on oregano essential oil adulteration is scarcer than evidence of adulteration of the herb itself. However, there are published reports of admixture of other, lower-cost essential oils with oregano oil, as well as the addition of the pure compounds carvacrol, thymol, or limonene (naturally occurring characteristic chemical compounds found in true oregano essential oil which are sometimes made by chemical synthesis).

The new bulletin, written by Ezra Bejar, PhD, an expert in botanical research in San Diego, California, lists the known adulterants, summarizes current analytical approaches to detect adulterants, and provides information on the nomenclature, supply chain, and market importance of oregano. It also discusses safety aspects of the known adulterants. The BAPB was reviewed by 19 experts from the nonprofit research sector, contract analytical laboratories, and the herb industry.

Stefan Gafner, PhD, chief science officer of ABC and the technical director of BAPP, commented: “In the past, researchers have mainly investigated the authenticity of oregano as a spice, where the addition of undeclared other plant materials appears to be quite widespread. It is not clear if these fraudulent practices are also occurring in the dietary supplement supply chain which is dominated by extracts and essential oil products. If so, we hope that the oregano bulletin will provide companies in the oregano trade with helpful information to enable the detection of adulterated raw materials.”

The oregano bulletin is the 19th publication in the series of BAPBs and the 54th peer-reviewed publication published by BAPP. As with all publications in the Program, the BAPBs are freely accessible to all ABC members, registered users of the ABC website, and all members of the public on the Program’s website (registration required).

About the ABC-AHP-NCNPR Botanical Adulterants Prevention Program

The ABC-AHP (American Herbal Pharmacopoeia)-NCNPR (National Center for Natural Products Research at the University of Mississippi) 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. To date, more than 200 United States and international parties have financially supported or otherwise endorsed the Program.

To date, the Program has published 54 extensively peer-reviewed articles, Botanical Adulterants Prevention Bulletins, Laboratory Guidance Documents, and Botanical Adulterants Monitor e-newsletters. All of the Program’s publications are freely available on the Program’s website (registration required).