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Workshop: Addressing Challenges in the Assessment of Botanical Dietary Supplement Safety

herbals or herbal dietary supplements

April 26-27, 2016
9 a.m. - 5 p.m. EDT
Location: Lister Hill Auditorium

National Institutes of Health (NIH), Bethesda, Maryland

The safety of botanical dietary supplements, hereafter referred to as botanicals, is an important public health issue.  According to the 2012 National Health Interview Survey, 17.7 percent of Americans reported having used nonvitamin, nonmineral dietary supplements (including botanicals) in the past 12 months (Clarke et al., 2015).  Botanicals pose several unique challenges to efficacy and safety evaluation because of their inherent complexity and potential for wide variability in nominally related products.  The interrelated challenges associated with the evaluation of botanicals include: (1) developing methods and criteria for assessing phytoequivalence (i.e., similarity in chemical composition and biological activity) of botanicals, (2) identifying the active constituent(s) or patterns of biological response of botanicals, and (3) assessing absorption, distribution, metabolism, and elimination (ADME) of botanicals.  This workshop will engage experts from multiple disciplines to focus on practical approaches for addressing these challenges.

Multiple factors contribute to the variability in botanicals including complex and inconsistent source material, manufacturing processes, formulation, and storage.  Botanicals in commerce often display a wide range in the concentration of known constituents.  Robust procedures for comparing constituent profiles across multiple botanicals are needed to determine how broadly safety or efficacy evaluations with a specific product can be applied to related products.  Topics for discussion at the workshop include definition of important chemical and biological activity features, statistical methods for comparing across complex mixtures, and how to define “similarity” across botanicals (i.e., how similar do botanicals have to be in order to apply safety data from a reference botanical to nominally-related botanicals).

Botanicals are often perceived to have significant health benefits with low risk of harm.  Since botanicals are complex natural products, the particular constituent(s) responsible for biological activity, as related to efficacy or toxicity, is often unknown.  Participants at the workshop will discuss the relative merits of dedicating scientific attention to identifying the active constituent(s) in botanicals and identifying biological signatures that are predictive of adverse events (biomarkers of effect).  Furthermore, presentations will address promising approaches (e.g., high throughput screening, computational tools) and accompanying challenges for using these approaches to advance our understanding of the risks associated with botanical use.   

Understanding the ADME of botanicals is critical to evaluating their safety.  However, evaluating ADME in humans and animal models is complicated in the case of botanicals by the large number of constituents, the wide range of concentrations, potential interactions (botanical-botanical and botanical-drug interactions), as well as interindividual and animal-to-human differences in pharmacokinetics.  The workshop will include discussion of knowledge gaps and available options for assessing ADME of botanicals to inform future safety evaluations.    


Clarke, T.C., et al., Trends in the use of complementary health approaches among adults: United States, 2002–2012, in National health statistics reports. 2015, National Center for Health Statistics: Hyattsville, MD.

Federal Register notice (PDF/HTML) - published December 18, 2015
Speaker Abstracts (listed alphabetically)
NIH VideoCast (Day 1)
NIH VideoCast (Day 2)

Note: Individuals with disabilities who need accommodation must request it at least five business days prior to the meeting. TTY users should contact the Federal TTY Relay Service at 800-877-8339. Otherwise, contact Dr. Rider for assistance.

Contact information

For questions or additional information contact: