A Sept. 7 Health report incorrectly stated that a journal article said synephrine, an ingredient in the weight-loss supplement Bitter Orange, speeds up the rate at which certain drugs enter the bloodstream, making it potentially dangerous for some users. The flavonoids in Bitter Orange have that effect. The Health article also incorrectly identified the American Botanical Council as a trade group. It is a nonprofit research and education organization. (Published 9/10/04)

Bitter Pill A weight-loss supplement promoted as a safer alternative to banned ephedra may pose serious health risks, according to a report by Georgetown University Medical Center researchers. The metabolism booster Citrus aurantium, aka bitter orange, contains synephrine, a chemical compound that is structurally similar to ephedra and epinephrine (adrenaline).

Why Worry? In their report in this month's issue of Experimental Biology and Medicine, Georgetown physiology professors Adriane Fugh-Berman and Adam Myers say numerous studies have shown that synephrine elevates blood pressure and speeds up the rate at which certain drugs enter the bloodstream. That makes synephrine potentially dangerous for those taking medications like warfarin (used to prevent blood clots) for which there's a narrow margin between effective and toxic doses, Fugh-Berman said.

But Wait Mark Blumenthal, executive director of the American Botanical Council, a trade group (whose advisory board includes Fugh-Berman), dismissed the findings, saying they were drawn primarily from studies in which synephrine was delivered intravenously. The only two studies that looked at people taking bitter orange orally found no effect on blood pressure, said Blumenthal, and there have been no reports of illness or deaths related to bitter orange. "There's no compelling evidence that, taken in moderate amounts, bitter orange poses any health risks," he said.

Playing Safe The Georgetown researchers say people -- especially those with cardiovascular problems or on daily meds -- shouldn't use bitter orange until it's proven safe. Remember, said Fugh-Berman, ephedra was banned last spring because it caused heart problems and strokes -- but when it was first being promoted, no clinical studies proved it was dangerous, either.

-- Lisa Barrett Mann