You’ve probably seen the headlines by now: four large retailers were just ordered by the New York State Attorney General’s office to stop selling their store brands of herbal dietary supplements due to allegedly mislabeled or adulterated ingredients.[1] But what you probably haven’t seen yet—because the media didn’t report it—was that the DNA testing used was not appropriate for herbal supplements.

Science was inappropriate and actions taken were premature

You and I likely agree that the dietary supplement industry has problems. But experts in botany, pharmacognosy, and natural product chemistry—three key scientific areas related to herb and medicinal plant research—are calling the testing flawed, scientifically-inappropriate, and inconsistent with the FDA’s Current Good Manufacturing Practices (cGMP) for herbal product quality control (detailed procedures for validating composition and purity).[2,3]

What did the New York Attorney General’s study find?

Based on the results of a single study, using testing methods known to not often work for identifying the contents of herbal extracts, the Attorney General’s office ordered GNC, Target, Walgreens, and Wal-Mart to stop selling seven herbal supplements: Ginkgo biloba, St. John’s Wort, Ginseng, Garlic, Echinacea, Saw Palmetto, and Valerian root. The office utilized a contracted researcher, James Schulte, PhD, of Clarkson University, whose background is in evolutionary biology and reptilian zoology—not botany, pharmacognosy, or natural product chemistry.

Products from the New York state retail stores were allegedly tested up to five times each by a DNA barcoding technique. The testing determined that only 4 percent to 41 percent of products contained DNA from the plant species indicated on the product label. Some samples had absolutely no DNA in them and others had DNA from the wrong plants.

DNA testing not appropriate as sole testing for herbal extracts

Researchers and expert scientists involved in herbal dietary supplement quality are criticizing the study and the Attorney General’s actions, saying the study is not based on adequate science the cease-and-desist order is thus premature.[2,3]

While herbal products containing the whole plant would certainly be expected to have the appropriate DNA, few herbal supplements are sold this way anymore. Instead, manufacturers prepare extracts of the plant using organic solvents like alcohol and numerous other commercial extraction processes. In many of these complex herbal extracts, little or no DNA is actually extracted. “…The plant DNA would be long gone by the time the final, finished product was produced, so finding no DNA in many of these products would actually be expected.”[3]

“The use of DNA barcoding technology for testing of the identity of botanical dietary supplements is a useful but limited technology. DNA testing seldom is able to properly identify chemically complex herbal extracts…,” according to a statement released by the non-profit American Botanical Council.[2]

The American Botanical Council, in conjunction with the University of Mississippi’s National Center for Natural Product Research and the American Herbal Pharmacopeia, is a leader in developing and implementing methods to assure authenticity in plant-based dietary supplement products. Their Botanical Adulterants Program issues guidelines for the most appropriate analytical techniques for the authentication of specific botanical materials.

The best test depends on type of plant and form of product

The most appropriate methods depend on whether the product being tested is in the form of whole, cut, or powdered raw materials, extracts, or something else. The best analytical method for the product may be based on genetic, microscopic, and/or chemical tests, including those commonly known as HPTLC, HPLC/UHPLC, flow-injection MS, NMR, and NIR hyperspectral imaging. Even the United Stated Pharmacopia’s dietary supplement verification methods, which are sometimes more outdated that those recommended by Botanical Adulterants Program, require the demonstration of known active chemicals from the herbal products, not DNA.

No follow-up testing or control?

Not only that, but the scientists are correct in pointing out that it is inappropriate for the Attorney General’s office to base its actions on only one testing technology from only one laboratory. The correct scientific procedure would be to conduct additional testing to confirm the initial results. Researchers who study herbal extract quality would typically follow up using microscopic analysis and validated chemical methods for further substantiation.

Results don’t agree with other recent studies

Another troubling issue with the Attorney General’s contracted study results is that they don’t agree with recently published DNA studies on commercial ginkgo extracts conducted at the New York Botanical Garden and the highly respected University of Mississippi’s National Center for Natural Product Research. Two recent tests on commercial ginkgo extracts from these reputable laboratories have found ginkgo in all or almost all of the samples tested.[4,5]

How to get the best out of herbal supplements

Like you, I am fully aware that the dietary supplement industry has issues that must be addressed. But is this the best way to handle the industry’s problems—using faulty research methods to prematurely pull products from the market? We all deserve access to pure, unadulterated supplements as well as accurate and reliable information about them. I strongly disagree with critics’ assertions about the general poor quality and ineffectiveness of dietary supplements. Every day, I read and write about high-quality, peer-reviewed, clinical studies documenting the effectiveness of natural supplements for treatment and prevention of all kinds of health conditions. Unfortunately, not all supplements on store shelves contain what they’re supposed to. For the time being, I urge you to do research before purchasing any supplements. Stick with companies that maintain the highest quality assurance standards and extensive testing programs.

[1] Attorney General Schneiderman. Press Release. Feb 3, 2015.

[2] American Botanical Council. Press Release. Feb 3, 2015.

[3] Forbes. Pharma and Healthcare. Cease-and-Desist… Feb 3, 2015.

[4] J Agric Food Chem. 2014 Dec 17;62(50):12103-12111.

[5] Genome. 2014 Sep;57(9):513-516.