Consumers of natural health products beware. The majority of
herbal products on the market contain ingredients not listed on the label, with
most companies substituting cheaper alternatives and using fillers, according
to new research from the University of Guelph.
The study, published today in the open access journal BMC
Medicine, used DNA barcoding technology to test 44 herbal products sold by 12
Only two of the companies provided authentic products
without substitutions, contaminants or fillers.
Overall, nearly 60% of the herbal products contained plant
species not listed on the label.
Researchers detected product substitution in 32% of the
More than 20% of the products included fillers such as rice,
soybeans and wheat not listed on the label.
"Contamination and substitution in herbal products
present considerable health risks for consumers," said lead author Steven
Newmaster, an integrative biology professor and botanical director of the
Guelph-based Biodiversity Institute of Ontario (BIO), home of the Canadian
Centre for DNA Barcoding.
"We found contamination in several products with plants
that have known toxicity, side effects and/or negatively interact with other
herbs, supplements and medications."
One product labelled as St John's wort contained Senna
alexandrina, a plant with laxative properties. It's not intended for prolonged
use, as it can cause chronic diarrhea and liver damage and negatively interacts
with immune cells in the colon.
Several herbal products contained Parthenium hysterophorus
(feverfew), which can cause swelling and numbness in the mouth, oral ulcers,
and nausea. It also reacts with medications metabolized by the liver.
One ginkgo product was contaminated with Juglans nigra
(black walnut), which could endanger people with nut allergies.
Unlabelled fillers such as wheat, soybeans and rice are also
a concern for people with allergies or who are seeking gluten-free products,
"It's common practice in natural products to use fillers
such as these, which are mixed with the 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."
Standard methods and
Until now, verifying what's inside capsules or tablets has
posed challenges, Newmaster said. His research team developed standard methods
and tests using DNA barcoding to identify and authenticate ingredients in
"There is a need to protect consumers from the economic
and health risks associated with herbal product fraud. Currently there are no
standards for authentication of herbal products."
Medicinal herbs now constitute the fastest-growing segment
of the North American alternative medicine market, with more than 29 000 herbal
substances sold, he said.
More than 1 000 companies worldwide make medicinal plant
products worth more than $60 billion a year.
About 80% of people in developed countries use natural
health products, including vitamins, minerals and herbal remedies.
Canada has regulated natural health products since 2004.
Regulators face a backlog of licence applications, and thousands of products on
the market lack a full product licence. Globally, regulatory problems involving
natural health products continue to affect consistency and safety, Newmaster
"The industry suffers from unethical activities by some
of the manufacturers."
The study also involved research associate Subramanyam
Ragupathy, U of G student Meghan Gruric and Sathishkumar Ramalingam of the
Bharathiar University in India.