St. John's Wort for Irritable Bowel Syndrome?

St. John's wort (SJW), an herbal preparation extracted from Hypericum perforatum, has been used to treat patients with mild-to-moderate depression. Because irritable bowel syndrome (IBS) is associated with depression, SJW is sometimes used as an alternative treatment for IBS.

To assess SJW's effectiveness in this setting, investigators evaluated 70 IBS patients (mean age, 42; 86% women; 29% with constipation-predominant IBS; 37% with diarrhea-predominant IBS; 31% with mixed IBS) who were randomized to receive SJW tablets (450 mg twice daily) or placebo in double-blind fashion for 12 weeks.

After 12 weeks, patients treated with placebo reported greater improvements than those treated with SJW in overall bowel symptoms (P=0.03), diarrhea (P=0.0…