Getting Safer Supplements: Why DNA Testing Is Not the Answer

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GNC has struck a deal with New York Attorney General Eric Schneiderman, ending the battle that's been raging ever since the Schneiderman ordered GNC, Walgreens, Walmart, and Target to stop selling herbal products that his secret investigation deemed fraudulent or hazardous. As part of this agreement, Schneiderman announced that GNC's supplements were compliant with federal law after all and cleared them to return to store shelves. And even though GNC had ample third-party verification to prove its products had not been unadulterated, the chain agreed to bolster its testing protocols to include the DNA barcode testing used in Schneiderman's probe.

The attorney general called this a "landmark agreement" that will help protect consumers against adulterated herbal supplements and rein in the loosely regulated supplement industry. There's just one problem: DNA barcoding is at best a problematic technology.

Most of the herbs in supplements are herbal extracts, not intact plants. Since an herb's DNA is usually destroyed during extraction, DNA barcoding will not normally detect it. Therefore, multiple botanical experts — and even some of the supplement industry's harshest critics — say that DNA barcoding is the wrong test to use. "Although DNA barcoding can be very reliable when applied to crude plant material, for extracts, it's not all it's cracked up to be," says Mark Blumenthal, founder of the American Botanical Council, a nonprofit botanical research organization. If the lab had instead used a suitable testing method, Blumenthal believes GNC's supplements would have checked out — as they did when the company had them analyzed properly by a third-party lab.

As for the DNA of rice, weeds, and other plants, this also may not be as scandalous as it seems. "If a stray dandelion blows into a field of ginseng, dandelion DNA might show up in a barcode test," says Dan Fabricant, former director of the FDA's Division of Dietary Supplement Programs and the current CEO of the Natural Products Association. "But that doesn't mean there's actually dandelion in the finished product."

Ingredients used in manufacturing can also show up in a DNA test, Blumenthal adds. "Since DNA barcoding is qualitative, not quantitative, it will pick up that DNA and amplify it as much as anything else in the product," he says. Even so, there may not be enough of that ingredient for it to matter, or even for manufacturers to be required to list it on labels as a potential allergen.

"Because of GNC's agreement, DNA barcoding is now perceived as the best analytical method, when in reality it may not be," Blumenthal says. "What's going to happen when other companies don't agree to this standard?" Or can't agree to it? While GNC manufacturers its own products and sources some of its own raw materials, Walmart, Walgreens and Target do not, which is why they've stayed mum. 

Blumenthal also believes that the GNC deal will create more headaches for consumers, rather than protecting them from fraudulent products, which are predominantly made by fly-by-night brands not sold at GNC or the other retailers. "This type of activity will only result in a patchwork quilt [of regulations]," says Blumenthal. "The reason we have the Interstate Commerce Act is to level the playing field. I'm concerned about how these actions will affect products sold at a national level."

But at the end of the day, even if DNA barcoding requirements won't offer you much additional protection, the most positive thing to come from this may be a heightened emphasis on transparency — which almost always bodes well for consumers. "This whole story sends a signal to the industry," Fabricant says. "We have a perception problem that we need to address. And the only way is to so is to increase transparency."