2021 USP Open Forum: Elderberry Standards Development

elderberry standards development

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An Open Forum about Elderberry Standards Development was hosted by the United States Pharmacopeia (USP) on January 22, 2021. More than 100 participants attended the virtual event, where USP engaged stakeholders to obtain their input, perspectives, and feedback about issues involving quality standards for Elderberry. The attendees included dietary supplement manufacturers, regulatory agencies, academic researchers, and contract labs.


Since the emergence of COVID-19, consumer demand has increased for certain herbal/botanical supplements purported to have anti-viral or immunomodulating activity. Among the most popular is European Elderberry, Sambucus nigra, which has a long history of traditional use as a cold and flu remedy. Some dietary supplements provide Elderberry as a single ingredient, while others are multi-ingredient formulations containing other botanicals, zinc, and/or vitamin C. The increased demand and limited supply of traditional Elderberry species has created a situation that raises the risk for adulteration. As a result, products on the market may be adulterated with ingredients that can mimic the composition or color of Elderberry ingredients when quality testing is performed. USP has developed a monograph for European Elderberry Dry Extract, together with three reference standards, which became official on March 1, 2019. In general, a monograph and reference standards can serve as tools or resources that manufacturers and regulators can use to promote quality and consistency of dietary supplement ingredients.

The main topics discussed at the Open Forum are summarized below.

  • Concerns about detecting adulteration and contaminants in Elderberry
    The main adulteration concerns are:
    • Species substitution. The use of Sambucus williamsii is increasing drastically in the market and might not always be declared on the label of products.
    • Use of other, cheaper sources of anthocyanins (especially black rice). Most of the evidence collected so far reveals adulteration of bulk extracts, but adulteration with black rice extract has also been detected in some gummy or chewable gel products. Currently there is no reference standard material available for other anthocyanins sources used for adulteration; building a library or database of the HPLC anthocyanin profile of the different sources used as natural colorants could be a valuable project to embark on.
    • Use of synthetic dyes (amaranth and Sudan dyes). Amaranth dyes are suspected carcinogens and have the potential for adverse events with other dyes. Also, there is always a potential for a food sensitivity or allergy/adverse reaction.
  • Taxonomy, or classification, of different species of Elderberry and its implications for dietary supplements
    • The most common species are European Elder followed by American Elder. The fact that subspecies are separated by geography may have led to over-description of the species.
    • A radical change in taxonomy/classification was introduced by Bolli in 1994. In the field of taxonomy, you can combine or separate different species and subspecies. Bolli combined the subspecies together. Most post-1994 authors have not accepted Bolli’s classification, but some others accept part of his classification.
    • Correct nomenclature: i) Sambucus nigra L. and Sambucus canadensis L., or ii) according to Bolli, Sambucus nigra L. subsp. nigra and Sambucus nigra L. subsp. canadensis (L.) Bolli, which depends on your preferred classification. Plants are “real” whereas taxa are theoretical. All of this relates to labeling, i.e., for accuracy and honesty in the labelling.
    • The best way to distinguish closely related species is by starting in the field, with a wild harvested species. Although some species have very similar macroscopy, the chemical profile could help differentiate them. Differentiation by chemical analysis becomes important when the material is processed into powders. Microscopy analysis of powdered material also becomes important to detect adulteration. Stakeholders using the USP HPLC method have been able to differentiate European from American Elder so far, but this will be researched further.
    • The USP Dietary Supplement and Herbal Medicine (DSHM) Nomenclature Joint Subcommittee has decided that because European and American Elder have different profiles, it would be best to have different monographs.
  • Purported efficacy of Elderberry
    • There is no proven efficacy of Elderberry for COVID-19, and in fact there is no clinical data at all on Elderberry for COVID-19. Some data suggest that Elderberry can reduce symptoms of the common cold.
    • It is not known which compounds in Elderberry are the most bioactive, anthocyanins versus other polyphenols. Although the USP monographs focus on analysis of the four main anthocyanin compounds in Elderberry, this does not guarantee efficacy. The purpose of the USP monograph is to propose quality criteria based on marker compounds or surrogate markers.
    • In addition, USP monographs are supported by technical specifications from manufacturers, in this case showing standardization of the ingredient on anthocyanins. Besides anthocyanins, the current monograph also considers other polyphenols (phenolic acids and flavonoids) present in Elderberry to complete the identity test by HPTLC profiling.
    • There is a concern in industry since some Sambucus canadensis (American Elder) products are implying they have the same efficacy as European Elder, even though it is well known that the anthocyanin profile is different. It would be helpful to carry out clinical studies with American Elder.
  • Methodologies for identifying and measuring anthocyanins and other polyphenols in Elderberry ingredients
    • The USP HPLC-UV anthocyanins method used for the identity and composition tests seems very robust as a compendial method. The HPTLC identity test also provides additional information to complement the anthocyanins profile. A multi-pronged approach like the one proposed in the USP monograph, combining HPLC and HPTLC profiles, makes it possible to overcome possible spoofs that can occur with the use a single analytical approach.
    • USP is developing more modern methods and needs stakeholder input. Due to its increased sensitivity, HPLC-MS is very valuable for the analysis of complex matrixes such as multicomponent formulations containing vitamin C and other nutrients, which can impact the chromatogram of anthocyanins. Both HPLC-MS and NMR are useful tools to further investigate adulteration, but they are more sophisticated and expensive techniques.
    • The usefulness of spectrophotometric methods to measure total anthocyanins or total polyphenols for quality control during manufacturing was discussed. However, it was agreed that they are not specific enough for compendial applications or to detect adulteration in Elderberry ingredients.
  • Need for development of new USP Elderberry standards for the different types of ingredients and dosage forms
    • A scheme describing the different types of Elderberry ingredients on the market was discussed with the attendees to better understand the need to develop new USP monographs and reference standard materials. Based on the information received from manufacturers, new standards for Elderberry liquid extracts, aqueous extracts, regular strength juices, juice concentrates, dried juice concentrates, and fruit powders can be of value to industry. Moreover, for each ingredient category, individual monographs for European Elder and American Elder need to be developed.
    • The importance of creating new Elderberry juice standards, which are currently missing from existing pharmacopeias and other standard-setting organizations, was discussed. Tests for organic acids and sugars are considered identification and authentication requirements for fruit juices and juice-derived ingredients, which are the most important category of Elderberry ingredients on the market. Examples of the usefulness of existing juice standards for Pomegranate Juice and Cranberry Juice were highlighted.
    • The role played by the Definition section of the USP monograph was described to explain how USP sets specifications to allow flexibility for ingredients falling into the same category but developed by different technologies (for example, use of different extraction solvents in the elaboration of dry extracts).
    • Attendees proposed the possibility of developing a monograph that would only focus on the fingerprint for different species instead of content specifications. The experience of USP in developing identity standards for food ingredients was also highlighted to support this possible route for standard development.
    • The spectrum of dosage forms for Elderberry is very wide, including sachets, effervescent tablets, capsules, gummies and other chewables, lozenges, syrups, liquid extracts, tinctures, decoctions, and infusions. USP requested input from attendees for the prioritization of new standards, keeping in mind that some of these finished products are used by children (age 2 years and above).
    • Attendees were concerned about the use of carriers and the related labeling requirements because some products are excessively diluted with carriers and consumers should know this. A USP working group is developing new guidelines on plant-to-extract ratio for botanical ingredients in order to make the labeling more transparent for consumers. This is a very important issue, especially for juice-derived ingredients like most Elderberry ingredients (which are not considered botanical extracts, per se). There are two ratios to consider; the first ratio is related to the original Brix level of the juice concentrate. The second ratio is the juice-to-finished powder ratio, which is indicative of the amount of carriers used during the spray-drying process.
    • The value of developing individual USP Reference Standard materials for European and American Elder was also highlighted. USP will examine the HPTLC and HPLC profiles of different types of ingredients and dosage forms from both species and will gather more supporting information from stakeholders in order to propose a new reference standard for American Elder.

Next steps

  • USP appreciates the participation of all attendees and the support of those manufacturers that have already submitted technical information and analytical samples.
  • USP welcomes additional, ongoing input from manufacturers, regulators, and others. In particular, prioritization of monographs for dosage forms and multi-component formulations needs to be established.
  • In the future, more Open Forums and other types of discussions may be held. Please watch for updates from USP.
  • If needed, training on use of the monograph(s) may be offered.
  • Stakeholders are encouraged to share with USP their Elderberry technical information (specifications, sheets, certificates of analysis, and manufacturing flow charts) and analytical samples for the development of new monographs and reference standards.

Please contact Maria Monagas, Senior Scientific Liaison (mjm@usp.org) with any questions or comments. We welcome your feedback!

The United States Pharmacopeia (USP) is an independent, nonprofit, science-based organization that seeks to improve global public health. USP convenes and engages a broad range of stakeholders through its Open Forum events and other programs. Open Forums provide an opportunity to share information on current, impactful topics. A top priority for USP is to solicit input from all stakeholders so that all perspectives are heard. These discussions may lead to networking and collaboration among diverse stakeholders, thereby bolstering efforts to improve global public health.