Dietary Supplements: Defective Products, Defective Standards

*Clinical Associate Professor, Pharmacy Practice and Administration, UMKC School of Pharmacy, 4239 NHSB, 2464 Charlotte, Kansas City, MO 64108; e-mail: mcqueenc@umkc.edu Lately, the biggest topic in the herbal medicine/ dietary supplement arena seems to be the quality of supplements sold on store shelves. This has been an issue of concern and sometimes quite heated debate for a long time, but the flames were fanned in February 2015. The New York Attorney General’s office sent “cease and desist” letters to several major retailers that were selling dietary supplements, based on a study showing that a majority of the supplements did not contain what they were labeled as containing.1 This was no surprise to most pharmacists and other health care practitioners. Problems with quality in the supplement industry have existed as long as the industry, back beyond the snake-oil salesmen in the old West to the times when one could purchase bones of saints or magical amulets to ward off cholera-causing demons. But the result raised quite a few eyebrows because, if we are going to rely on science, then the science needs to be accurate and as clear-cut as possible; and many practitioners and researchers had serious questions about the appropriateness of the sole identification test used in the study – DNA barcoding. There is no question that DNA barcoding, also called DNA fingerprinting, can be an accurate test for the identification of botanical matter.2 But like any tool, it must be used properly. The big question is whether the test was used appropriately in the New York study. DNA testing can be appropriate for “whole herb” types of dosage forms, which are dried herbs ground and put into a capsule or combined with excipients and compressed into tablets. However, many herbal products are extracts. DNA barcoding may not be appropriate for those, as United States Pharmacopeia (USP), the nation’s standard-setting organization for prescription drug and over-the-counter (OTC) products, explained in their response to the New York situation.3 The “why” may be most easily explained to patients and consumers with an example from daily life: When you buy a cup of good quality coffee, do you expect to find coffee grounds? Usually not, as that is a clue that preparation of your drink was less than ideal. Coffee is an aqueous extract – a solvent (hot water) comes in contact with botanical matter (coffee beans) and leaches out various chemicals. Herbal extracts prepared into capsules or tablets undergo a great deal more processing (and very often use solvents other than water), but the basic idea is the same. A “perfect extract” should include only extracted chemicals, so that a negative result on a DNA test would be considered reason for celebration rather than condemnation. However, perfection is rarely achieved. Even extracts with some original botanical material intentionally remaining could present with negative results for DNA tests, if the extract process involved excessive heat or chemicals causing DNA damage.3 The same is true for heat-processed whole herb preparations. Of course, things are rarely as simple as analogies imply; some herbal medicinal products consist of combinations of extracts and original plant materials and therefore should have positive DNA test results. Examining the list of various supplements that were tested (echinacea, garlic, ginkgo, ginseng, St. John’s wort, saw palmetto, valerian root), it is very likely that both whole herb products and extract products were included in the New York study.1 Extracts with identified concentrations of certain “active ingredients” or marker compounds are usually recommended, or should be, over whole herb products for all listed supplements except possibly