Quoted from The Hundred-Year Lie:

For thirty years James A. Duke was a botanist for the United States Department of Agriculture and chief of the USDA Medicinal Plant Laboratory. He ranks as one of the world’s leading authorities on botanical medicine, a term that describes medicinal trees and shrubs along with the herbs and medicinal plants used by traditional societies. “I’ve personally seen medicinal herbs successfully treat conditions that high-tech pharmaceuticals could not touch,” declares Duke. “I’ve also used many of these medicinal remedies myself.”

In Duke’s experience the botanical remedies are often more effective, more economical, and much safer than the pharmaceuticals that try to imitate them. His extraordinary book, The Green Pharmacy, published in 1997, gives hundreds of natural botanical remedies for arthritis, diabetes, backache, toothache, emphysema, cataracts, menopause, and on and on. He declares his life’s ambition to be “getting the FDA to make the drug companies test their new synthetic drugs not only against an inactive substance [a placebo] but also against any known or suspected herbal alternative.

“I wrote this book to show that traditional medicine has legitimate scientific value. Scientific critics counter that ‘old folk tales’ are no match for Western-style scientific experimentation. But the basis of science is careful observation, and that’s what traditional peoples have been doing since time immemorial—observing and experimenting with the world around them. In general, traditional people have managed to select the good medicines and have rejected the bad. Most of these folk medicines have thousands of years of experimental selection behind them, and few are associated with adverse reactions. That’s something that you really can’t say about our modern pharmaceuticals. All too often, synthetic drugs turn out to be hazardous.”

Fitzgerald, Randall (2006-06-22). The Hundred-Year Lie: How to Protect Yourself from the Chemicals That Are Destroying Your Health (pp. 199-200). Plume. Kindle Edition.