How Not to Test Dietary Supplements

Echinacea capsules look harmless enough. They promise immune support, natural healing, and centuries-old botanical wisdom packed neatly into a pill. But what if what’s inside the bottle isn’t echinacea at all?

Echinacea is, beyond dispute, a striking pink flower from the daisy family, native to the American plains. According to a small body of scientific research—much of it conducted in Germany—it may help stimulate the immune system. Advocates claim it can treat everything from the common cold to liver toxicity when consumed as tea, tincture, or capsules. These claims, however, have never been evaluated by the U.S. Food and Drug Administration (FDA), which classifies echinacea not as a drug but as a dietary supplement—a far less strictly regulated category.

And yet, consumers reasonably assume that a bottle labeled “Echinacea” actually contains echinacea.

Last week, that assumption was shaken.

What’s Really in the Capsule?

New York Attorney General Eric Schneiderman announced that his office had tested a range of store-brand herbal supplements sold by major retailers including Walgreens, Walmart, Target, and GNC. The results were alarming: many of the echinacea products contained little to no echinacea DNA. Instead, they were composed largely of rice, houseplant material, and other fillers.

The findings didn’t stop there. Target’s valerian root supplements contained garlic and wild carrot—but no valerian. Walgreens’ St. John’s wort included garlic, rice, and dracaena, a common houseplant. Walmart’s ginkgo biloba consisted of dracaena, mustard, wheat, and radish.

For consumers, the reaction was immediate: confusion, anger, and a sense of betrayal. At best, they had been paying for placebo pills. At worst, they had been deliberately misled.

DNA Barcoding Enters the Scene

To conduct the analysis, Schneiderman’s office enlisted Beckman Coulter Genomics and a biologist from Clarkson University named James Schulte. The team used a method known as DNA barcoding, which identifies organisms based on short, species-specific genetic sequences—much like scanning a barcode at a grocery store.

The technique was pioneered in 2004 by biologist Paul Hebert at the University of Guelph, who envisioned a global database that would allow scientists to rapidly identify species by genetic signature alone. Since then, DNA barcoding has been used in conservation biology, pest control, biosecurity, and increasingly, food fraud investigations. The FDA itself adopted the method in 2011 to identify mislabeled fish.

On the surface, the case seemed airtight.

But science, as usual, is more complicated.

When the Test Is the Problem

Experts in pharmacology and food science quickly raised concerns—not about supplement fraud (which is real and widespread), but about the method used to prove it.

First, inert fillers like rice or wheat are legally allowed in dietary supplements, provided they remain below certain thresholds. Yet there was no indication that the DNA tests accounted for quantity.

Second, industrial processing can destroy DNA without destroying the active compounds responsible for a supplement’s effects. Heat, irradiation, solvents, and extraction processes can all degrade genetic material. As Markus Lipp of the U.S. Pharmacopeia (USP) put it bluntly:“DNA is extremely fragile. The moment it’s stressed, it breaks down.”

In other words, a supplement could contain genuine echinacea compounds—even if echinacea DNA is no longer detectable.

The Limits of DNA Alone

This raises a critical question:

If echinacea DNA is gone due to processing, why does rice DNA remain?

The likely answer is timing. Rice powder is often added after extraction, as a filler. Its DNA remains intact, while the plant DNA has already been degraded.

USP scientists emphasize that DNA barcoding is not recommended as a standalone test for highly processed botanical supplements. Instead, USP certification relies on chemical assays that detect specific phenols, alkylamides, and acids—markers that confirm both identity and potency, regardless of DNA integrity.

DNA may tell you what was once there. Chemistry tells you what still works.

The Bigger Picture

None of this means dietary supplement fraud isn’t a serious problem. It is. But choosing the wrong scientific tool can undermine even the right fight.

Under U.S. law, pharmaceuticals must meet USP identity standards. Dietary supplements, however, are held to a far looser definition of “appropriate and scientifically valid” testing. Schneiderman’s office appears to have decided that DNA barcoding meets that bar. USP disagrees.

As Gabriel Giancaspro of USP explains, DNA testing may one day be part of a broader toolkit—but never the only instrument.

Science, Trust, and Consumer Protection

Dietary supplements are not always what they claim to be—and they don’t always do what they promise. But in this case, the investigation may have relied on a method better suited to identifying species than judging processed products.

When it comes to public trust, scientific precision matters. Fighting fraud requires not just good intentions, but the right evidence.

Otherwise, even the truth can become misleading. By Nicola Twilley

February 10, 2015 https://www.newyorker.com/tech/annals-of-technology/dna-barcoding-new-york-dietary-supplement#rid=563336df-33a8-486a-b2a4-468aa23957f2&q=supplement