Scientific research can be a slow process. It starts with simple observation, followed by the collection of scientific data. A few years ago, an Austrian herbalist named Maria Treben wrote a bestselling book that was translated into English as Health Through God's Pharmacy (Ennsthaler, 1998). In it, she recommended a tea prepared from the small-flowered willow herb (Epilobium parviflorum) as an effective treatment for benign prostatic hyperplasia (BPH), or prostate enlargement. The herb became very popular in Europe, but there was no evidence to support its value.
Scientists have isolated compounds known as oenotheins from the Epilobium species and, in test-tube experiments, have shown them to inhibit the enzymes aromatase and 5-alpha-reductase, both of which are involved in prostate enlargement. Clinical studies have not yet been carried out, but the signs are hopeful that the traditional use of this herb will be validated. Willow herb is not yet widely available in the US.