Dietary Supplements - Quality
"Dietary supplement" is regulatory term. Dietary supplements include vitamins, minerals, herbs, botanicals, fatty acids, and amino acids which are administered as capsules, tablets, liquids, gels or powders. The FDA regulates dietary supplements based on 1994 Congressional legislation referred to as DSHEA (Dietary Supplement Health Education Act). While the consumer is guaranteed access to a wide variety of supplements by the current legislation, and guaranteed access to promotional literature and dosage suggestions, quality of dietary supplements is not assured. Although counterintuitive, the contents listed on the label of a dietary supplement do not always correspond to the actual contents in the bottle, when the contents of the bottle are subject to third party biochemical analysis. There is extensive published documentation of sub-potent products, contamination of products with toxic metals (lead, mercury, and others), pesticides, herbicides, aftlatoxin, bacteria, PCBs and dioxin. At times, third party analysis shows that a toxic solvent used to create an extract of an herb remains in the finished product. There are some instances of adulteration of a product, possibly a function of inadvertent misidentification of an herb in its natural environment, such that the herb in the bottle is not the herb on the label. One example of this is skullcap, listed in the Consumer Reports May, 2004 "Dirty Dozen," even though the published literature indicates that the liver toxicity of the skullcap product was due to mislabeling of germander, which is known to be toxic to the liver.
DSHEA in 1994 mandated that the FDA establish good manufacturing practices (GMPs) for dietary supplements. The FDA did not issue the "Final Rule" for cGMPs for dietary supplements until June 22, 2007, thirteen years after the DSHEA legislation was passed by Congress. The rule ensures that dietary supplements are produced in a quality manner, do not contain contaminants or impurities, and are accurately labeled. The final cGMP and the interim final rule became effective October 24, 2007. To minimize any adverse impact upon small businesses manufacturers of dietary supplements, the rule had a three-year phase-in for small businesses. Companies with more than 500 employees had until June 2008 to comply, companies with less than 500 employees had until June 2009 to comply, and companies with fewer than 20 employees had until June 2010 to comply with the regulations. The final rule itself, 814 pages, published in the Federal Register, is posted here. Some experts have identified concerns with the comprehensiveness of the final rule - two critiques are published in Integrative Medicine: A Clinician's Journal (IMCJ. 2007. 6. 8-9 and 28-31).
Resources at the FDA to monitor compliance of manufacturers with the Final Rule are limited, and thus FDA action tends to be reactive rather than proactive. Thus, the consumer who shops for supplements based on price alone may be purchasing an inferior quality product, or worse, an adulterated or contaminated product. Fortunately, there are a variety of trade groups and private businesses that provide information for the consumer who wishes to purchase high quality products. Consumerlab is a business which purchases a variety of brands of popular dietary supplements off the shelves of health food stores and pharmacies, and from internet sites, contracts for independent analysis of each brand for quality, and posts the results of the independent analysis on its web site. There is a nominal annual fee to subscribe to Consumerlab and access the information posted on the site. In addition to Consumerlab, there are businesses which certify manufacturers of dietary supplements for Good Manufacturing Practices. Certification of high-quality manufacturing is available through NSF, NPA, and USP - web sites which list companies which are certified are available here, here and here. Beware though that even if a company is certified by NSF, NPA or USP, this information is not necessarily included on the product label. Beware also that NPA and NSF certifications address only the chemical composition, not the bioavailability of the herb. USP and Consumerlab do address bioavailability as well as chemical composition. A newer resource is information posted on the website of Emerson Ecologics, a business that serves health care professionals as a distributor for multiple manufacturers. Emerson initiated a quality program in 2010, ranking manufacturers based on a number of criteria. Information is posted here regarding manufacturers who meet the standards to qualify as either "Gold Partner," "Silver Partner," or "Partner." The limitation of this database is that manufacturers who choose not to distribute through Emerson Ecologics will not be listed in any of the categories.
For herbs, it is essential that manufacturers use analytical methods to confirm the identity of the herb (avoid inadvertent adulteration). These analytical methods include HPTLC (high-pressure thin-layer chromatography), HPLC (high performance liquid chromatography) and DNA barcoding (the newest technology). NOTE that DNA barcoding is valuable for analyzing the whole herb, but not necessarily valuable for analyzing extracts, as most of the DNA may be removed with extraction. In 2015, the NYS Attorney General claimed adulteration of some herbal products based on DNA barcoding of extracts; industry experts objected to the conclusions based on mis-use of this technology
Disclaimer: the preceding is intended as educational material and not as individual treatment recommendations.
Page Updated January 2, 2016; reviewed July 3, 2017