Many pharmaceuticals were, or are still derived from natural sources. Herbs of all kinds are unquestionably of great value. I think a big problem with many or most of the natural sources available in stores or internet is the variance in the amount of the important active chemicals. If you read 6 labels, you will find 4 or 5 different ways to measure what you are taking. All of which are nearly impossible to meaningfully compare. I have read there is also reason to doubt the accuracy of what is labeled in terms of active ingredients and their strength or bioavailability.