On February 3, 2015, New York State Attorney General Eric Schneiderman released results of DNA testing of herbal supplements at major local retail chains. See the AG's announcement.

Over half of Americans consume over 85,000 different supplements, including botanicals, spending $32 billion annually. Attorney General Schneiderman drew inspiration from a 2013 study performed at the University of Guelph in Canada, wherein a third of supplements tested with DNA barcoding did not find traces of the botanical being sold, only fillers. The Attorney General tested store brand bottles of St. John's Wort, ginseng, Ginkgo biloba, valerian, garlic, and saw palmetto at major local chains: Wal-Mart, GNC, Target, and Walgreen Co. Testing of samples using DNA barcoding alone were performed by James Schulte II of Clarkson University in Potsdam, New York. Results indicated that only 21% of the store brand supplements contained DNA fragments of the botanical product sold. Additionally, DNA evidence of rice, beans, wheat, and some unidentified contaminants were found. In response to these findings, Mr. Schneiderman noted that these products should be removed from the stores immediately, with the burden of proof on the industry to demonstrate that botanical products can be validated for authenticity and safety.


The American Botanical Council (ABC) retorted that relying on DNA barcoding technology alone to validate botanicals is premature. Traditionally, botanicals are analyzed using validated chemical methods or microscopic analysis to identify chemical constituencies of products. The ABC argued that DNA in botanicals may not be present in sufficient quantity or quality, due to the methods used in processing herbs, which may destroy DNA (e.g., heating). Furthermore, many supplements are made from extracts of herbs alone, which they argue would not contain DNA. See ABC's response.

How reliable is DNA barcoding technology in authenticating botanical supplements?

While the Attorney General's intentions may have been good, questions remain as to the conclusion of the study: that the botanical supplements were falsely labeled or dangerous until proven otherwise. However, DNA barcoding technology is relatively new, and questions remain regarding its accuracy; it is not the gold standard. It consists of identifying short DNA fragments, which are compared to a library of known plant and animal species. The test itself must be assessed further for its accuracy (the originators of the test at the University of Guelph claim 88% accuracy for supplements of plant and animal origin). It would help, for example, to do DNA barcoding on an extract to see if DNA is indeed found after processing, rather than assume the supplier is mislabeling or adulterating products on purpose. Similarly, it is unclear if "contaminants" are small fragments of DNA we might find in almost any product, rather than "fillers," or if these other substances produce adverse effects.

From a scientific perspective, the veracity of the results would be strengthened by central review of the testing, multiple test centers, and the use of traditional testing methods as a control. In contrast to the current study, in two separate studies of Gingko biloba extracts done at other centers, evidence of Gingko extracts was indeed present in a majority of samples. While the rebuke from the Attorney General's office was swift, with consumer confidence shaken, the debate is not yet settled.

A case for more oversight and testing

In Canada, supplements have been regulated since 2004 by Health Canada through the Food and Drugs Act and Natural Health Products Regulation. In the US, the FDA only gets involved with natural supplements in cases of serious adverse events that warrant investigation. In 1994, the Dietary Supplement Health and Education Act led to the current standard of assuming supplements are safe until proven otherwise. A proposed 2012 amendment, the Dietary Supplement Labeling Act, would have forced natural supplements to be registered with the FDA, providing more safety information to consumers, but it did not pass. It should be noted that despite FDA oversight, drug adverse events easily dwarf those from natural supplements.

While consumers are increasingly reaching for natural supplements, many assume that what comes from "nature" must be safe. However, the fact that an agency can independently test supplements and question the trust in this industry demonstrates that more oversight is needed to assure consumers that they are not completely dependent on suppliers to ensure safety. For the public to move forward with confidence in natural supplements, more pre-market testing and validation is necessary, otherwise similar impromptu tests could occur elsewhere and create more doubt in the authenticity of these products.

The Society of Integrative Oncology is founded upon the principles of evidence-based practice with safety in mind. We believe that natural supplements have a place in health care as a whole, and the evidence is growing in terms of efficacy and mechanism of action for many of these products. It is clear that many are inclined to take natural supplements for a variety of reasons. What we must do is ensure safety and transparency. We should be working together the business community, medical and scientific community, as well as regulatory forces to ensure that we are promoting standards that are accepted, enforced, and fair.

1. Cohen, Peter A. Hazards of Hindsight – Monitoring the Safety of Nutritional Supplements. NEJM 2014; 370: 1277-80.
2. O'Connor, A. Herbal Supplements Are Often Not What They Seem. New York Times, Nov 3, 2013.
3. O'Connor, A. New York Attorney General Targets Supplements at Major Retailers. New York Times. February 3, 2015.
4. A.G. Schneiderman Asks Major Retailers to Halt Sales of Certain Herbal Supplements as DNA Tests Fail to Detect Plant Materials Listed on Majority of Products Tested [press release]. Albany, NY: New York Attorney General's Office; February 3, 2015. Available at: www.ag.ny.gov/press-release/ag-schneiderman-asks-major-retailers-halt-sales-certain-herbal -supplements-dna-tests
5. Little DP. Authentication of Gingko biloba herbal dietary supplements using DNA barcoding. Genome. 2014 Sep; 57 (9): 513-16.
6. Wang M, Zhao J, Avula B, et al. High-resolution gas chromatography/mass spectrometry method for characterization and quantitative analysis of ginkgolic acids in Ginkgo biloba plants, extracts, and dietary supplements. J Agric Food Chem. 2014 Dec 17; 62(50): 12103-111.
7. Newmaster, Steven G, Grguric, Meghan, et al. DNA Barcoding Detects Contamination and Substitution in North American Herbal Products. BMC Medicine 2013, 11: 222.
8. ABC Says New York Attorney General Misused DNA Testing for Herbal Supplements, Should Also Have Used Other Test Methods as Controls: Media coverage does not mention known limitations of DNA testing protocols. http://cms.herbalgram.org/press/2015/ABCSaysNYAttyMisusedDNA.html?ts=1424146972&signature=561d9ec175d29b81900a1c007d2e0d17.

By, Santosh Rao, MD