An Herbal Caution

The belief that an herbal or botanical supplement is "natural" and therefore can be only beneficial, even in high doses, is incorrect. Many vitamins and herbal compounds are toxic at high levels. There is currently no regulatory oversight of herbal supplements, which has led to hazardous doses and contaminants in marketed products. Consumers should be warned about the use of high-dose supplements of any type. There is not evidence that any nutritional supplements can reproduce the apparent benefits of a diet high in vegetables and fruits. It is always advisable for patients to inform their health care providers about any vitamin, herbal or botanical supplement use.

More: http://pathology2.jhu.edu/pancreas/nutrition.cfm#herbal