As herbal products are mostly unregulated you need to put in your due diligence to make sure you are buying from a reputable source. As this late 2013 study indicates, the majority of the companies tested were not delivering as promised.
Usually your herbalist will have a good understanding of which sources of herbal products can be trusted. Regulation may not be the solution as industry in general marginalizes herbal solutions. Do not assume the herbs you buy at a health food store are of a good quality. Do your homework.
The University of Guelph press release about the study: http://www.uoguelph.ca/news/2013/10/study_herbal_pr.html
From the press release:
The study, published today in the journal BMC Medicine, used DNA barcoding technology to test 44 herbal products sold by 12 companies. Only two of the companies provided authentic products without substitutions, contaminants or fillers. Overall, nearly 60 per cent of the herbal products contained plant species not listed on the label. Researchers detected product substitution in 32 per cent of the samples. More than 20 per cent of the products included fillers such as rice, soybeans and wheat not listed on the label.
From the study:
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 an SRM 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.
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