Many herbal products don't list all ingredients and contain fillers

Study: Herbal products omit ingredients, contain fillers

Here's the first paragraph:
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 report says approximately 60 per cent of the products tested had cheaper alternatives.

Of great danger to people with allergies, is this quote from the story

More than 20 per cent of the products included fillers such as rice, soybeans and wheat not listed on the label.