When Canadian researchers recently ran tests on popular herbal products on sale in the US and Canada they found one third contained no trace of the plant advertised on the bottle.
The researchers used DNA barcoding – a type of genetic fingerprinting – to test 44 products representing 12 companies and 30 different species of herbs.
Their study found that most (59%) of products tested contained plant species not listed on the labels – substituted ‘ingredients’ included weeds and powdered rice.
The researchers wrote: “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.”
Industry groups in America have criticized the study’s “flawed” methodology, claiming that DNA barcoding is of limited use in identifying herbs.
The Canadian researchers decided not to name brands or manufacturers.