It's odd that the U.S. turned against herbs since many modern drugs owe their origins to medicinal plants. Morphine comes from the opium poppy. Digitoxin, used to stimulate the heart and regulate its rhythm, comes from foxglove. Autumn crocus gives us colchicine, an anti-inflammatory drug used to treat gout, and belladonna provides atropine, a heart stimulant and treatment for Parkinson's disease. The cancer drug vincristine comes from periwinkles.
Researchers continue to examine the components of plants in their search for new medicines.
Proof of their safety and efficacy are not required. In fact, the government hasn't even established a standard of quality for herbal products. The best bet may be to buy European herbal products, which must adhere to strict guidelines. The guidelines not only standardize the herbal extracts according to chemical or biochemical markers, they also set limits on contaminants and require that the ingredients be stable over time. In any case, it's important to check purchases, use, and doses of these products with qualified professionals such as pharmacists and herbalists, and to discuss potential side effects.