In the September 2002 issue, Delicious Living reported that researchers who have conducted recent studies on St. John's wort (Hypericum perforatum) suggest that there are limits to the herb's effectiveness as an antidepressant; other researchers who have conducted additional studies suggest St. John's wort may help with anxiety and memory disorders, but also raise cautions about its interaction with certain drugs.

Researchers conducting a recent study sponsored by the National Institutes of Health (NIH) may have opened the way to a new use for St. John's wort in anxiety disorders. In 2001, the study's lead researcher published case reports of three patients that linked supplementing with St. John's wort extracts to quelled anxiety. Another area of promise for St. John's wort extract, suggested by a 2002 study, is in the treatment of memory disorders and in enhancing the performance of mental tasks. One of St. John's wort's active components is hyperforin, which can alter the amount of the nerve chemical messenger acetylcholine. This messenger, derived from the nutrient choline, is involved in memory and in muscle movement. Because altering choline can affect muscle control, however, the study's researchers suggest that people with Parkinson's disease or other movement disorders avoid St. John's wort.

Finally, recent studies suggest that St. John's wort can alter the metabolism of anesthetic drugs, causing a delay in "coming out" from anesthesia. Therefore, it's best to avoid taking St. John's wort before receiving general anesthesia.

While extensive St. John's wort research continues, more is required before this plant extract can be recommended for other disorders. A large U.S. clinical trial will further explore St. John's wort's effectiveness in the management of mild to moderate depression, where its use currently appears most prudent.

Nutrition and exercise biochemist Anthony Almada, MS, has collaborated on more than 45 university-based studies and is cofounder of Experimental and Applied Sciences (EAS) and founder and chief scientific officer of IMAGINutrition.