New research for the University of Guelph shows that the majority of herbal products on the market contain ingredients that are not listed on their labels.
The study, published in the journal BMC Medicine, used DNA barcoding technology to assess the components of 44 herbal products from 12 companies. They found that 60% of the products contained plant species that were not listed on the label, and 20% used fillers like rice, soybeans, and wheat which were also not divulged on the bottles.
For instance, products sold as St. John’s wort supplement, which is sometimes used to treat depression, contained Senna alexandrina, which is a plant that spurs laxative symptoms. Other products contained Parthenium hysterophorus (feverfew), which is known to cause swelling and mouth numbness. One ginkgo product contained Juglans nigra (black walnut), which should not be consumed by people with nut allergies — but this warning was not noted on the label.
“It’s common practice in natural products to use fillers such as these, which are mixed with active ingredients. But a consumer has a right to see all of the plant species used in producing a natural product on the list of ingredients,” lead author Steven Newmaster, an integrative biology professor at the Guelph-based Biodiversity Institute of Ontario said in a statement.