Continual magic bullet view of DNA barcoding frustrates testing expert

By Hank Schultz

- Last updated on GMT

Related tags Dna testing Species Plant Dna

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A recently aired media report once again seemed to elevate DNA testing to magic bullet status. It’s a development that dismays Danica Harbaugh Reynaud, PhD, one of the foremost experts in the DNA testing of plants.

The report, aired last week on the investigative TV show Frontline​, took at face value a number of cases in which DNA tests were used to look at the quality and authenticity of dietary supplement finished goods. One case was a paper published by Steven Newmaster, PhD, of the University of Guelph, the other was the widely criticized first attack on the herbal products industry by New York Attorney General Eric Schneiderman. Newmaster’s original tests, which many in industry believe may have formed the basis for Schneiderman’s initial foray, were first made public in 2013 in an open access journal. These were taken by the show’s producers as gospel and Newmaster was quoted at length in the show. What the producers either didn’t know or did not see fit to include was that his findings of widespread adulteration and substitution of herbal products were so gravely flawed in the eyes of herbal experts that the American Botanical Council called for the outright retraction of his findings​ in a paper that was co-authored by Harbaugh Reynaud herself.

No magic bullet

Harbaugh Reynaud, CEO of DNA testing firm Authen Technologies that was acquired earlier this month by NSF, said that DNA testing can be a powerful tool, but is not the simplistic one-size-fits-all technique that was alluded to in the show.  That aspect of the diagnostic tool is best reserved for crime fiction where definitive answers are a staple feature of many scripts, she said.

“I think they do tend to think of it as a magic bullet. It’s interesting to see that people like NY AG Schneiderman seem to assume that any DNA testing is good DNA testing. We have to think about how it was done and who was doing it,” ​she told NutraIngredients-USA.

Harbaugh Reynaud said that to equate tests done for species in the animal kingdom with those of plants is to misunderstand the challenges of the technology. Plants might be considered ‘lower’ organisms, but taken as a whole the kingdom presents a much more complex DNA picture.

“Hands down plants are going to be the most difficult type of organism to deal with. Tests for animals are going to be unreliable for plants,” ​she said.

“Most animals are very distinct from one another, and there are not very many species compared to plants. With plants you deal with many thousands of species and the species can often be very closely related to one another,”​ Harbaugh Reynaud said.

Making those fine distinctions can be crucially important in the plant kingdom, she said.  DNA testing has recently been used to distinguish substitutions in the marketing of fish, where the flesh of less desirable species has been fraudulently substituted for more expensive types. In the plant arena, it can be more grave, even up to a matter of life and death, she said.

“Star anise is a good example.  One variety is great in food;  its very close relative can kill you,” ​she said.

Long road to reliable technology

Harbaugh Reynaud said that, while difficult, it is possible to develop a viable plant DNA testing methodology that is repeatable.  NSF, with the addition of her company, now has a big leg up in this arena, she said.  She worked for a number of years refining the method and building a library of authenticated DNA reference materials for use in botanical identification. In her opinion, it is a service that for the moment stands above the rest of the marketplace in terms of its comprehensiveness.

“If we are looking 10 or 15 years in the future I think we will probably see this being done in more labs around the world. But just as buying a scalpel doesn’t make you a surgeon, buying a next generation gene sequencer doesn’t make you a DNA testing lab. It took us 15 years to develop this technology. There are going to be lag times for new entrants to the market. When we started doing this there were no other companies offering this service,” ​she said.

The demand for DNA testing will only grow, Harbaugh Reynaud believes. For example, GNC in its agreement with Schneiderman committed itself to instituting these tests within its supply chain where appropriate.  Even so, Harbaugh Reynaud said that the tests, however good they might become, should still be viewed as only one arrow in the quiver.

“We would never recommend DNA testing on its own. Other types of chemical tests are necessary and other checks to determine that the proper plant part is being used. But we see DNA testing as the first line of defense.  As we tell clients, it’s better to know what’s in your product before someone else does,”​ she said.

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