NEW YORK (Reuters Health) – While many people swear by the benefits of certain herbal therapies, a review of the medical literature provides only incomplete evidence of efficacy, making any risk benefit assessment unreliable, a UK researcher reports in the Annals of Internal Medicine for January 1.
In a review of published studies of ginkgo, St. John's wort, ginseng, Echinacea, saw palmetto and kava, Dr. Edward Ernst from the University of Exeter, found that what clinical trials existed were too short, too small and too few.
Data from these studies showed that ginkgo had some positive effects on dementia and impaired circulation, but is of questionable value for memory loss and tinnitus. St. Johns wort was effective for mild to moderate depression, but adversely interacts with many common drugs, decreasing their effectiveness.
Echinacea may be of benefit in the prevention and treatment of upper respiratory infection, but the data are unconvincing. Saw palmetto did reduce symptoms of benign prostatic hyperplasia in the short-term, and kava appears effective in reducing anxiety in the short-term. Ginseng was of no proven benefit in treating any condition.
While there are books on these remedies, Dr. Ernst finds them for the most part useless. "According to our preliminary evaluation, these books represent more of a risk to the health of the reader than a helpful source of knowledge," he notes.
Dr. Ernst concludes that "dissemination of objective rather than promotional information, stimulation of rigorous research and provision of adequate funds are clearly the way ahead and should be of interest to all parties concerned. Rigorous and systematic evaluation of all herbal medicinal products is urgently needed."
Ann Intern Med 2002;136:42-35