Many of the most-adulterated natural products and supplements on the market, as well as the most common adulterants, are not on most people’s radar. When we think about adulteration in the natural products industry, typically we think about adulterants like active pharmaceutical ingredients, fraudulent fillers, and trace allergens. But did you know that a high percentage of botanicals are actually contaminated with other plants—even toxic plants? Most don’t realize this.
For instance, many don’t know that grasses such as oat grass and barley grass, as well as alfalfa, are among the most-adulterated natural products. Surprisingly, one of the top-selling herbs that can be found in kitchens around the world—oregano—is also highly adulterated. In fact, according to an NSF AuthenTechnologies annual review of over 1200 samples from nearly 250 different plant species, over 82% of the oregano samples we tested were contaminated or adulterated in some way by another plant species. (This review was conducted at our next-generation DNA testing lab in California.) Half of the oregano samples contained bindweed (Convolvulus arvensis), a common weed found on roadsides around the world. In some samples, most of the DNA in a bottle of “oregano” actually came from bindweed, not from oregano. It turns out that bindweed is one of the most prevalent adulterants in the natural product supply chain. More than 5% of all botanical samples that we’ve tested over the past year contain this toxic plant.
Bindweed gets into the natural product supply chain as an artifact of poor harvesting practices or as a fraudulent filler. In either case, bindweed can be hazardous to health. Phytochemicals present in bindweed can cause potentially serious health problems. Known adverse effects in animal research include hallucinations, liver damage, ulcers, and even cardiac arrest.
Widespread Botanical Adulteration
In our annual review, NSF AuthenTechnologies found that more than 50% of the plant samples we tested were, in fact, adulterated. This study is not only the most comprehensive review of botanical authentication data to date; it also reveals some pretty alarming and unexpected trends in adulteration.
In addition to bindweed, our study detected nearly 30 other toxic plant adulterants in nearly 150 plant samples, including several “legal high” herbs used as substitutes for recreational drugs.
One such herb is kratom (Mitragyna speciosa). In September, the U.S. Drug Enforcement Agency asked FDA to add kratom, a highly addictive herb whose adverse effects can lead to death, to the agency’s list of Schedule I drugs. On FDA’s import-alert website, FDA says, “there does not appear to be a history of use or other evidence of safety establishing that kratom will reasonably be expected to be safe as a dietary ingredient. In fact, the scientific literature disclosed serious concerns regarding the toxicity of kratom in multiple organ systems. Consumption of kratom can lead to a number of health impacts, including respiratory depression, nervousness, agitation, aggression, sleeplessness, hallucinations, delusions, tremors, loss of libido, constipation, skin hyperpigmentation, nausea, vomiting, and severe withdrawal signs and symptoms.”
In the results from our annual review, we detected kratom in an everyday cinnamon sample. As a mother of two girls, I find these examples of adulteration in common foodstuffs highly alarming.
The Value of Targeted Next-Generation DNA Sequencing
Considering just how insidious botanical adulteration can be, it’s crucial to identify good tools to catch adulteration. DNA testing is a method with a growing profile in recent years.
There is no denying that DNA testing has changed the landscape of numerous fields, such as forensics and medical diagnostics. Like computer microchips that get smaller, faster, and more powerful every year, DNA testing methodologies are becoming cheaper, faster, and more accurate.
Traditional DNA testing techniques have their limitations, however. DNA barcoding, for instance, which uses Sanger Sequencing, falls short in authenticating samples that are processed, including adulterated samples of commercial products. Luckily, there’s a next generation of DNA sequencing that can help identify numerous species in a wide range of processed materials, and in only a few hours and for less, compared to many other traditional methods.
We call this technology Target Specific DNA Sequencing (TSDS). TSDS detects and identifies unwanted and unexpected adulterants, contaminants, and even toxic weeds. Because the test methods are unbiased, TSDS is also a great method for assessing current trends in adulteration throughout the natural product supply chain, from seed to shelf.
Using the power of Next Generation Sequencing (NGS) technology, TSDS applies specific tests that target unique regions of the genome and that can both authenticate the plant species and identify adulterants. Each specific test relies on a unique combination of polymerase chain reaction (PCR) primers, or probes, which produce millions of copies of each species in the material. Unlike traditional barcoding, which uses only long, universally available PCR primers for all species, the TSDS process also uses unique, short, genus-specific primers. These short primers allow the technology to test a much wider range of products than traditional DNA barcoding can handle, including products that are heated, processed, and extracted.
Once the DNA copies are produced, an NGS machine will elucidate the unique arrangement of bases (A, C, G, T) in the sequence. Each sequence is then compared to a validated reference DNA database for identification.
What Can TSDS Do?
In addition to identifying unexpected botanical adulterants and contaminants, TSDS can indicate the potential presence of an allergen. In a recent study we conducted of ground black and white pepper samples purchased from multiple retailers around the world, we identified fillers and contaminants in approximately 75% of the products tested. In fact, the white pepper samples frequently contained unlabeled wheat or rice flour, posing a potentially serious health risk to those with related allergies. And these fillers weren’t just present in trace levels; in many cases, they comprised a majority of the DNA in the product. Also surprisingly, even products labeled as “non-GMO” and “organic” were not immune to adulteration by these fillers and allergens.
Novel methods such as TSDS are uncovering important trends in botanical adulteration. This is important, because it is critical for suppliers and testing labs to understand which species are commonly adulterated so they can take the necessary precautions to eliminate them from finished products. This information can also be useful to suppliers, manufacturers, and retailers as an early warning system for possible issues that could be detrimental to their businesses and may require further action in areas such as cleaning procedures, cross-contamination in the field or facility, or issues even further down the supply chain.
Source: Nutritional Outlook
