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New York Attorney General Bashes Herbal Supplement Purity

Analysis: Industry questions technique used by New York to slam supplement product purity

by Marc S. Reisch
February 16, 2015 | A version of this story appeared in Volume 93, Issue 7

Credit: Marc Reisch
GNC and three other stores have been asked to pull some herbal supplements from shelves in New York.
A GNC Store in New York City.
Credit: Marc Reisch
GNC and three other stores have been asked to pull some herbal supplements from shelves in New York.

Dietary supplement makers are crying foul over analytical tests used by the State of New York to determine their products’ purity. Results of the tests led to a demand by the state attorney general that four major retailers halt the sale of certain herbal supplements because of suspect ingredients.

The tests used what is known as the DNA bar code technique. Close to 80% of the tests conducted for New York State Attorney General Eric T. Schneiderman’s office identified DNA from plant species other than those listed on the labels. Products tested included echinacea, ginseng, and St. John’s wort. Schneiderman is requiring GNC, Target, Walgreens, and Walmart to prove their supplements are properly labeled before putting them back on store shelves.

DNA bar coding is a method for identifying organisms using a short genetic marker, but the supplement industry argues that it has shortcomings and shouldn’t be used alone. They are concerned about having more aspersions cast on a product category that has weathered numerous bans, recalls, and scientific doubts about safety and efficacy nationwide.

GNC points out that ingredients are often stripped of their DNA in the supplement manufacturing process. The firm says its herbal products are tested in conformity with methods from standard-setting bodies, such as the U.S. Pharmacopeia (USP), and that they comply with all regulatory requirements.

Active ingredient extraction techniques “can purify the DNA away,” says Gabriel Giancaspro, vice president of dietary supplements for USP. In general, supplement makers use a variety of test protocols, including liquid and gas chromatography, to verify ingredients and screen for contaminants, he says.

Tod Cooperman, president of, a consumer-funded supplement testing service, says he can’t tell if the contaminants Schneiderman found pose any real danger because a shortcoming of DNA bar coding is that it doesn’t provide information about the amounts of contaminants in samples. Cooperman acknowledges that heavy-metal contaminants are not uncommon in herbal ingredients, and points out that DNA bar coding can’t identify them.

Moreover, the attorney general didn’t seem to verify the DNA bar code results, complains Stefan Gafner, chief science officer of the American Botanical Council, an herbal medicine education group. “Microscopy and validated chemical test methods ... should have been conducted to confirm the DNA findings,” he says.

A spokesman for Schneiderman confirms that only DNA bar coding was used on samples and no third-party verification was done. “We’re now asking that the industry demonstrate what is in their products,” he says.



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