A recent study challenges the efficacy of the once-hallowed herbal supplement St. John's wort and confusion over the active ingredient and standard dosage may be partly to blame.
Jonathan Davidson, M.D., of Duke University, gave either St. John's wort, a placebo or the antidepressant sertraline to 340 patients with major depression. St. John's wort, for which Americans paid $170 million in 2000, did not fare much better than the placebo. This may be due to confusion over the active ingredient, long thought to be the herbal compound hypericin. The major player may actually be hyperforin, which is not standardized in supplements.
"Investigators agree that hyperforin is the major antidepressant constituent," says Gerlie C. de los Reyes, M.S., of the University of Southern California. But Reyes found that the amount of hyperforin in St. John's wort varies. In Reyes' study, published in the American Journal of Health-System Pharmacy, an extract containing 5 percent hyperforin was superior to the placebo in alleviating depressive symptoms, but the clinical effects of just half a percent of hyperforin were only comparable to the placebo.