Dr Len McEwen refers to the use of berberis tincture and then to the use of berberin as if they were in fact the same substance (WDDTY vol 5 no 12). They are not. Herbalists use whole plant exactions (berberis tincture is an example). They do not use extractions of single constituents from plants (berberin is one of these).
The other constituents within a whole plant extract will often limit the adverse side effects of the main "active" constituent. Aspirin is known to irritate the stomach lining, but when given in the form of Willow bark or Meadowsweet, this irritation does not occur because the plants contain mucilage and tannins which protect the stomach lining from these harmful effects.
Just because a substance is natural, it does not mean it is safe. In view of the ever increasing number of horror stories that come my way of wrongly prescribed herbal medicines, if people are given herbal medicine by any therapist, they should check that therapist is qualified to advise them in herbal medicine.
In the hands of a qualified and competent herbalist herbal medicine is very safe, but it is medicine and should be treated with respect. Christine Steward, Vice President, National Institute of Medical Herbalists, Exeter......