By Linda Formichelli, published on August 1, 2002 - last reviewed on January 23, 2015
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.
Yet hypericin remains the preferred marker ingredient for the
standardization of St. John's wort because of its relative stability-even
expired products show negligible degradation of this compound.