Measurements and Standards for Botanical Dietary Supplements

As part of a multi-year interagency agreement among the National Institute of Standards and Technology (NIST), the National Institutes of Health's Office of Dietary Supplements (NIH/ODS), the Food and Drug Administration (FDA) Center for Food Safety and Applied Nutrition (CFSAN), and the FDA Center for Drug Evaluation and Research (CDER), NIST is developing Standard Reference Materials (SRMs) for botanical dietary supplements.

SRMs with assigned values for concentrations of active and/or marker compounds, pesticides, and toxic elements are being produced to assist in the verification of manufacturers’ label claims and for use in quality control during the manufacturing process in support of the Good Manufacturing Practices released by the FDA in 2007.

Many consumers believe that botanical dietary supplements will improve their health and that these “natural” remedies are both effective and free from the side effects that may occur with other medications. There are occasional reports of inaccurate labeling, adulteration, contamination (with pesticides, heavy metals, or toxic botanicals), and drug interactions. Congress recognized the lack of publicly available, validated analytical methods for dietary supplements – and a lack of reference materials for validation of analytical methods – in 1994 when the Dietary Supplement Health and Education Act (DSHEA) was enacted. As part of DSHEA, NIH/ODS was directed to fund development of analytical methods and reference materials for dietary supplements. NIST’s dietary supplement program began in 2001 as a collaborative effort between NIST and NIH/ODS to underpin the then-anticipated GMPs. Subparts E and J of the GMPs require manufacturers to establish specifications for identity, purity, strength, and composition; to set limits on contaminants and adulterants for every ingredient in their products; and to analyze both “materials in process” and finished products to determine whether specifications are met. The validity of analytical methods must be verified and then routinely used for monitoring against the manufacturer’s specifications. Thus, the SRMs can be used both to demonstrate that a method is appropriate for its intended use and as a quality control material when demonstrating that specifications are met, ultimately reducing public health risks that may be associated with these products.

Listed below are materials that are currently available or for which Certificates of Analysis are in review. In most cases, these SRMs are provided as suites of materials (plant, extract, finished product) that represent different analytical challenges. The constituents for which values are assigned are also listed. The constituents in all of these materials have been determined by multiple independent methods with measurements performed by NIST and collaborating laboratories. The methods utilized different sample extraction and cleanup steps in addition to different instrumental analytical techniques and approaches to quantification. These materials are provided primarily for use in method development and as control materials to support the measurement of these constituents in other similar products. 

Suites of materials based on green tea, black cohosh, blueberries, bilberries, cranberries, soy, kudzu, and red clover are currently in progress.

Goals:

• Increase the types and availability of botanical dietary supplement SRMs to meet the needs of analytical laboratories, manufacturers, and regulators
• Develop methods of analysis for these materials
• Enable the establishment of a link to label information on botanical dietary supplements
• Provide calibration solutions for selected constituents in the botanical products

Nineteen natural-matrix SRMs have been produced with 34 more in progress.

Analytical methods have been developed for the measurement of ephedrine and citrus alkaloids, flavonoids, catechins, phytosterols, and organic acids.

Certificates of Analysis for these materials can be found at http://www.nist.gov/srm or by clicking the SRM numbers in the table below.