Quality Standards Issued for Testing Herbal Products

Dietary supplements

The National Institute of Standards and Technology (NIST) has issued the first suite of Standard Reference Materials (SRMs) in a planned series of reference materials for botanical dietary supplements.

The dietary supplement industry has exploded in the past decade to about 29,000 products, with about 1,000 new products introduced each year, according to the Food and Drug Administration (FDA). In 2001 NIST began working with the FDA and the National Institutes of Health's Office of Dietary Supplements (NIH/ODS) on a series of SRMs of popular botanical dietary supplements. Manufacturers can use these materials for quality control, and researchers can use them to ensure that their laboratory analyses of supplements are accurate. Products such as botanical supplements, that have been derived from extracts of plant materials are challenging to analyze accurately because of their complex sample matrices.

The new NIST reference materials were designed primarily for quality control of supplements containing ephedra, a plant once widely used in herbal weight-loss products. Ephedra products were pulled from the market by the FDA in 2004 after being linked to cardiovascular problems, but the new test materials remain valuable both to assure that new products are not adulterated with ephedra and because they also can be used to improve several other key measurements in other botanical supplements, including concentrations of potentially toxic heavy metals.

The new reference materials represent several different forms of ephedra and include powdered plant material (SRM 3240), a ground solid oral dosage form (SRM 3243), and a protein powder (SRM 3244). The materials are certified for their concentrations of the ephedrine alkaloids and potentially toxic elements (including arsenic, cadmium, lead and mercury). SRM 3243 also provides certified values for synephrine (a compound in some of the "ephedra-free" weight-loss products) and caffeine. SRM 3244 adds values for caffeine, theobromin, theophylline, and nutrients including fat, protein, carbohydrate, individual fatty acids and amino acids, vitamins and nutritive elements.

Future dietary supplement SRMs will include: Ginkgo biloba, saw palmetto, bitter orange, carrot extract, green tea, blueberries, cranberries, bilberries and St. John's wort. For further information visit www.nist.gov/srm