Most of the herbal products tested were of poor quality, including considerable product substitution, contamination and use of fillers. These activities dilute the effectiveness of otherwise useful remedies, lowering the perceived value of all related products because of a lack of consumer confidence in them. We suggest that the herbal industry should embrace DNA Barcoding for authenticating herbal products through testing of raw materials used in manufacturing products. The use of a standard reference material DNA herbal barcode library for testing bulk materials could provide a method for 'best practices' in the manufacturing of herbal products. This would provide consumers with safe, high quality herbal products.
That's from the abstract of a new publication that caused a bit of a hype in the press during the last few days. Colleagues here at the institute tested a variety of herbal products using DNA Barcoding. They published their finding in BMC Medicine and given their results it is no wonder that it got picked up by the press.
We recovered DNA barcodes from most herbal products (91%) and all leaf samples (100%), with 95% species resolution using a tiered approach (rbcL + ITS2). Most (59%) of the products tested contained DNA barcodes from plant species not listed on the labels. Although we were able to authenticate almost half (48%) of the products, one-third of these also contained contaminants and or fillers not listed on the label. Product substitution occurred in 30/44 of the products tested and only 2/12 companies had products without any substitution, contamination or fillers. Some of the contaminants we found pose serious health risks to consumers.
So, not only 'just' substitution and mis-labelling but also serious health risks through fillers and contaminants. One product labeled as St. John's wort (Hypericum perforatum) was actually fully substituted with Senna alexandrina which can cause adverse effects such as chronic diarrhea, cathartic colon, liver damage, abdominal pain, epidermal breakdown and blistering.
A Ginkgo product was contaminated with black walnut (Juglans nigra). If those traces were from the nuts this could lead to some severe problems for people with nut allergies. However, even if you are not allergic to nuts there is a problem as walnut leaves, woods, bark and fruits all contain juglone which has been listed as tumor agent that is known to promote skin tumors.
A while ago I wrote about a similar study that was done on a much smaller scale to serve as prove of concept. Seems there is a lot more going on in this industry than we initially thought and it would send a strong positive signal out to consumers if science, industry, and regulatory institutions could jointly work on fighting the unethical activities of some manufacturers. Again, no excuse - the tools are in place and we are working on the reference libraries to make them most efficient.