Chicago ? Children and teens with attention deficit hyperactivity disorder fared no better on St. John’s wort than they did on dummy pills in a government study, another blow for herbal supplements.

St. John’s wort, pine bark extract and blue-green algae are among commonly used herbal treatments for children with ADHD. They appeal to parents who want to avoid stimulants like Ritalin and other drugs used to help children control their behavior.

But unlike prescription drugs, supplements are only loosely regulated by the government and their makers don’t have to prove they are safe or effective.

“Do an Internet search and you’ll find a wide variety of herbal products marketed for ADHD,” said lead author Wendy Weber of Bastyr University’s School of Naturopathic Medicine in suburban Seattle. “I’ve found there is very little research on the majority of products out there.”

Weber, working with colleagues at Harvard University and University of Washington, focused on St. John’s wort because studies in rats found it increases brain chemicals like norepinephrine, which is thought to help focus attention.

In the study, appearing in today’s Journal of the American Medical Association, 54 children with ADHD were randomly assigned to take either St. John’s wort capsules three times a day or placebos. They ranged in age from 6 to 17 years old.

After eight weeks, the two groups showed no difference in symptoms or side effects.